Dissertations / Theses: 'Terrestrial laser scanning'

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Hetherington, David. "Terrestrial laser scanning of the river environment." Thesis, University of Salford, 2009. http://usir.salford.ac.uk/26714/.

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This thesis describes the results of three field studies concerned with the utilisation of terrestrial laser scanning in the river environment, over different spatial scales. Existing research and technical literature has also been reviewed relating to scale, form and process in the river environment, conventional measurement techniques and the general utility and testing of terrestrial laser scanning technology. In physical geography and geomorphology, scales of interest in the river environment can range from very small scales such as an individual grain up to large scales that cover entire floodplains or catchments. Improved measurement and spatial representation of the river environment over all these scales will reduce error and improve confidence in research into river form and process. Terrestrial Laser Scanning (TLS) - sometimes referred to as Terrestrial LiDAR (Light Detection and Ranging) - is an exciting and relatively new measurement technique that is based upon the time-of-flight principles of laser pulses from a static origin. The term "scanning" relates to the way that the laser pulses are systematically deployed and received in an automated fashion over a swath by the main measurement unit. These data are acquired from a terrestrial perspective, which gives the technique an advantage over airborne measurement and terrestrial contact measurement methods. This research's aim is to evaluate the performance of TLS as a tool for measuring and representing the river environment, whilst focusing on three distinct scales of river features - the reach scale, the floodplain/braid plain scale and the grain scale. Overall, TLS has proved itself to be an extremely useful tool for measuring and representing (spatially and temporally) the river environment, whilst focusing on various scales and features. This is especially the case when investigating rivers at the reach and plain scales. If used correctly, it can undoubtedly provide scientists and engineers with the data that they need to increase their knowledge of river environment form and process. The findings of this thesis have many broader implications relating to how TLS should be used and how it fits into the suite of measurement tools that we have at our disposal.

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Scharf, Alexander. "Terrestrial Laser Scanning for Wooden Facade-system Inspection." Thesis, Luleå tekniska universitet, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-77159.

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The objective of this study was to evaluate the feasibility of measuring movement, deformation and displacement in wooden façade-systems by terrestrial laser scanning. An overview of different surveying techniques and methods has been created. Point cloud structure and processing was explained in detail as it is the foundation for understanding the advantages and disadvantages of laser scanning. The boundaries of monitoring façades with simple and complex façade structures were tested with the phase-based laser scanner FARO Focus 3DS. In-field measurements of existing facades were done to show the capabilities of extracting defect features such as cracks by laser scanning. The high noise in the data caused by the limited precision of 3D laser scanners is problematic. Details on a scale of several mm are hidden by the data noise. Methods to reduce the noise during point cloud processing have proven to be very data-specific. The uneven point cloud structure of a façade scan made it therefore difficult to find a method working for the whole scans. Dividing the point cloud data automatically into different façade parts by a process called segmentation could make it possible. However, no suitable segmentation algorithm was found and developing an own algorithm would have exceeded the scope of this thesis. Therefore, the goal of automatic point cloud processing was not fulfilled and neglected in the further analyses of outdoor facades and laboratory experiments. The experimental scans showed that several information could be extracted out of the scans. The accuracy of measured board and gap dimensions were, however, highly depended on the point cloud cleaning steps but provided information which could be used for tracking development of a facade’s features. Extensive calibration might improve the accuracy of the measurements. Deviation of façade structures from flat planes were clearly visible when using colorization of point clouds and might be the main benefit of measuring spatial information of facades by non-contact methods. The determination of façade displacement was done under laboratory conditions. A façade panel was displaced manually, and displacement was calculated with different algorithms. The algorithm determining distance to the closest point in a pair of point clouds provided the best results, while being the simplest one in terms of computational complexity. Out-of-plane displacement was the most suitable to detect with this method. Displacement sideways or upwards required more advanced point cloud processing and manual interpretation by the software operator. Based on the findings during the study it can be concluded that laser scanning is not the correct methods for structural health monitoring of facades when the tracking of small deformations, especially deformations below 5 mm and defects like cracks are the main goal. Displacements, defects and deformations of larger scale can be detected but are tied to a large amount of point cloud processing. It is not clear if the equipment costs, surveying time and the problems caused by high variability of scans results based on façade color, shape and texture are in a positive relation to the benefits obtained from using laser scanning over manually surveying.

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Evans, Hywel F. J. "Construction material classification using multi-spectral terrestrial laser scanning." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33511/.

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This research addresses the problem of populating Building Information Model databases with information on building construction materials using a new classification method which uses multi-spectral laser scanning intensity and geometry data. Research in multi-spectral laser scanning will open up a new era in survey and mapping; the 3D surface spectral response sensitive to the transmitted wavelengths could be derived day or night in complex environments using a single sensor. At the start of this research a commercial multi-spectral sensor did not exist, but a few prototype level instruments had been developed; this work wished to get ahead of the hardware development and assess capability and develop applications from multi-spectral laser scanning. These applications could include high density topographic surveying, seamless shallow water bathymetry, environmental modelling, urban surface mapping, or vegetative classification. This was achieved by using from multiple terrestrial laser scanners, each with a different laser wavelength. The fused data provided a spectral and geometric signature of each material which was subsequently classified using a supervised neural network. The multi-spectral data was created by precise co-positioning of the scanner optical centres and sub-centimetre registration using common sphere targets. A common point cloud, with reflected laser intensity values for each laser wavelength, was created from the data. The three intensity values for each point were then used as input to the classifier; ratios of the actual intensities were used to reduce the effect of range and incidence angle differences. Analysis of five classes of data showed that they were not linearly separable; an artificial neural network classifier was the chosen classifier has been shown to separate this type of data. The classifier training dataset was manually created from a small section of the original scan; five classes of building materials were selected for training. The performance of the classification was tested against a reference point cloud of the complete scene. The classifier was able to distinguish the chosen test classes with a mean rate of 84.9% and maximum for individual classes of 100%. The classes with the highest classification rate were brick, gravel and pavement. The success rate was found to be affected by several factors, among these the most significant, inter-scan registration, limitation on available wavelengths and the number of classes of material chosen. Additionally, a method which included a measure of texture through variations in intensity was tested successfully. This research presents a new method of classifying materials using multi-spectral laser scanning, a novel method for registering dissimilar point clouds from different scanners and an insight into the part played by laser speckle interpretation of reflected intensity.

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Resop, Jonathan Patrick. "Terrestrial Laser Scanning for Quantifying Uncertainty in Fluvial Applications." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/38694.

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Stream morphology is an important aspect of many hydrological and ecological applications such as stream restoration design (SRD) and estimating sediment loads for total maximum daily load (TMDL) development. Surveying of stream morphology traditionally involves point measurement tools, such as total stations, or remote sensing technologies, such as aerial laser scanning (ALS), which have limitations in spatial resolution. Terrestrial laser scanning (TLS) can potentially offer improvements over other surveying methods by providing greater resolution and accuracy. The first two objectives were to quantify the measurement and interpolation errors from total station surveying using TLS as a reference dataset for two fluvial applications: 1) measuring streambank retreat (SBR) for sediment load calculations; and 2) measuring topography for habitat complexity quantification. The third objective was to apply knowledge uncertainties and stochastic variability to the application of SRD. A streambank on Stroubles Creek in Blacksburg, VA was surveyed six times over two years to measure SBR. Both total station surveying and erosion pins overestimated total volumetric retreat compared to TLS by 32% and 17%, respectively. The error in SBR using traditional methods would be significant when extrapolating to reach-scale estimates of sediment load. TLS allowed for collecting topographic data over the entire streambank surface and provides small-scale measurements on the spatial variability of SBR. The topography of a reach on the Staunton River in Shenandoah National Park, VA was measured to quantify habitat complexity. Total station surveying underestimated the volume of in-stream rocks by 55% compared to TLS. An algorithm was developed for delineating in-stream rocks from the TLS dataset. Complexity metrics, such as percent in-stream rock cover and cross-sectional heterogeneity, were derived and compared between both methods. TLS quantified habitat complexity in an automated, unbiased manner at a high spatial resolution. Finally, a two-phase uncertainty analysis was performed with Monte Carlo Simulation (MCS) on a two-stage channel SRD for Stroubles Creek. Both knowledge errors (Manning's n and Shield's number) and natural stochasticity (bankfull discharge and grain size) were incorporated into the analysis. The uncertainty design solutions for possible channel dimensions varied over a range of one to four times the magnitude of the deterministic solution. The uncertainty inherent in SRD should be quantified and used to provide a range of design options and to quantify the level of risk in selected design outcomes.
Ph. D.

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Reshetyuk, Yuriy. "Self-calibration and direct georeferencing in terrestrial laser scanning." Doctoral thesis, Stockholm : Arkitektur och samhällsbyggnad, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9879.

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Olsen, Michael James. "Methodology for assessing coastal change using terrestrial laser scanning." Diss., [La Jolla] : University of California, San Diego, 2009. http://nsgl.gso.uri.edu/casg/casgy09005.pdf.

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Thesis (Ph. D.)--University of California, San Diego, 2009.
Title from first page of PDF file (viewed July 14, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 258-267).

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Ososinski, Marek. "Environment perception in the context of 3D terrestrial laser scanning." Thesis, Aberystwyth University, 2016. http://hdl.handle.net/2160/8de63213-6dba-4062-8aca-be0335537b67.

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Terrestrial laser scanning has become a popular way of digitising buildings and complex environments. Laser scanning was adopted as the means of capturing 3D data in many elds, including architecture, engineering and environmental survey. It was only a matter of time for the Heritage sector to start using the technology. This thesis describes the scienti c contributions from the collaboration project that explored the viability of automating the laser data acquisition process. The project concentrated on the reduction of the skill set required by the operator of the laser scanner as well as the improvement of the usability of large datasets. The contributions involved the development of a new data representation method, a new visibility estimation metric and an improved volumetric decimation algorithm.

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Campbell, Lorraine. "Assessing the utility of Airborne Laser Scanning for Terrestrial Ecosystem Mapping." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62453.

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Observing landscape patterns at various temporal and spatial scales is central to mapping ecosystems. Traditionally, ecosystem mapping uses a combination of fieldwork and aerial photography interpretation. These methods, however, are time-consuming, prone to subjectivity, and difficult to update. Airborne Laser Scanning (ALS) is an advanced remote sensing technology that has increased in application in the past decade and has the potential to significantly increase and refine information content of ecosystem mapping, especially in the vertical dimension. ALS technology provides detailed information on topography and vegetation structure and has considerable potential to be used for terrestrial ecosystem classification and mapping. In this thesis, the potential to use ALS data to advance ecosystem mapping is examined. The current state of the science for using ALS data to classify and map key ecosystem attributes within an existing ecosystem mapping scheme is discussed by focusing on British Columbia’s Terrestrial Ecosystem Mapping (TEM) and its associated Predictive Ecosystem Mapping (PEM). Based on a detailed literature review, a site-specific case study was also developed with the goal of mapping TEM polygons for a forested landscape on Vancouver Island, British Columbia. To do so an object-based image analysis approach was used. The analysis examined which were the best suite of ALS-based terrain and vegetation metrics to define and distinguish individual site series. It established a workflow for the classification of site series within the study site and examined the capacity to map site series based on ALS derived values. Best segmentation parameters were first established and then the study area was classified for slope position-wetness and finally into the specific site series. In the classification of site series two approaches were used. One approach used only terrain metrics and the other incorporated vegetation metrics. Overall accuracies were 59% and 56% respectively. While this workflow requires refinement, it shows potential for improved accuracies by applying suggestions discussed. The thesis concludes with a discussion summarizing the findings of this research and highlighting future refinement to the methods applied in the case study, while also providing recommendations for the current application of ALS technology to TEM.
Forestry, Faculty of
Graduate

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Cardozo, Francisco Alberto Ramirez. "Terrestrial laser scanning measurements to characterise temporal changes in forest canopies." Thesis, University of Salford, 2011. http://usir.salford.ac.uk/26605/.

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Light detection and ranging (lidar) systems are active sensors capable of creating a permanent three-dimensional (3D) record of forest canopy structure. This 3D characterisation can provide increased accuracy for aboveground biomass estimates in high-biomass ecosystems, where passive optical sensors only provide a two-dimensional (2D) perspective. The aim of this study was to test a quantitative, accurate, and repeatable method to obtain estimates of canopy biophysical properties and monitor seasonal variations in forests by using multi-temporal terrestrial laser scanner (TLS) data. This research is one of the first detailed multi-temporal terrestrial lidar studies undertaken anywhere in the world. The study site chosen for this research was Delamere Forest, located in Cheshire, Northwest England. TLS data on vegetation structure were acquired for seven sampling plots, comprising two broad-leaf and five conifer stands, between March 2008 and April 2009. Canopy directional gap fractions were derived from the TLS datasets collected and compared with estimates derived from coincident hemispherical photographs. The comparison showed that TLS gap fractions estimates were consistently lower than those estimated from hemispherical photographs. To examine this apparent difference further the potential information available from the intensity values recorded by TLS were investigated. The use of this information in the computation of gap fractions led to a better agreement between estimates derived from both sources, as well as a better understanding of how intensity values are activated within forest canopies. Estimates of other biophysical properties were also computed from the TLS data, including leaf area index, average leaf angle distributions, and clumping index. The analysis of these estimates highlighted the repeatability and consistency of the TLS measurements in comparison with corresponding results derived from the hemispherical photographs. Analysis of the TLS datasets was conducted in order to improve the understanding of the interaction between lasers and vegetation canopies. The novelty of this research is in applying a ground-based lidar sensor to characterise the structure of a range of tree canopies using intensity corrected data, and assessing the utility of estimates of biophysical properties for monitoring temporal variations in forest canopies.

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Barber, David Matthew. "Terrestrial laser scanning for the metric survey of cultural heritage structures." Thesis, University of Newcastle Upon Tyne, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270827.

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Ryding, Joseph. "Assessing new methods for measuring forest understorey vegetation using terrestrial laser scanning." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/38078/.

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Forest structure is the complex 3D arrangement of all components within the forest architecture. This includes stems, foliage, branches (the components of trees) but also includes non-tree components such as understorey shrubs and herbs. Understanding the structural components of forests is critical when considering forest ecosystems. The structure of a forest can affect functional and compositional characteristics such as productivity and species richness with structure being an important factor influencing animal-habitat associations. Structural characteristics of forests include the size distribution and spatial organisation of trees, and the horizontal and vertical density of objects within the understorey. Trees are the dominant feature of any forest, but the understorey is also very important when considering forest characteristics. Examining the links between the spatial distribution of understorey material and ecological parameters, such as diversity and productivity, has an important role in ecological studies. There are multiple field survey techniques that can be applied when collecting data for a forest survey. For a technique to be an effective survey tool it should be readily quantifiable, repeatable, cost-effective, easily assessed, ecologically meaningful and where possible not contain observer bias. Traditional methods of forest survey are very common as they offer reliable, low cost estimations of forest structural parameters such as diameter, height and understorey cover. Recent developments within 3D data collection using terrestrial laser scanning (TLS) have allowed foresters and ecologists to reproduce the structural parameters collected during traditional forest surveys. These developments have shown the usefulness of 3D data collection in assessing forest structure, but have focused on replicating existing forest metrics rather than developing new ones. For TLS to reach its full potential within the field of forest ecology, new metrics and indices need to be developed specifically for laser scan analysis. This study developed and tested new methods of forest survey, concentrating on understorey vegetation, using commercially available TLS. Results showed that these new techniques can provide novel structural assessments of the understorey layers of forests for use in forest ecology surveys, not available through traditional methods. Using a new index describing the vertical component of forest understorey, it was shown how the relationship between deer browsing and forest structure can be identified through feature extraction from laser scanning. The method developed required minimal manual processing and was applied to large data sets. The structural changes between high and low deer density sites were also observed through the creation of an understorey density profile. This method, specifically targeted at the lower layers of the understorey, successfully identified structural change at the decimetre level. Using microtopography estimates from understorey point clouds it was shown how understorey complexity corresponded with vegetation surfaces extracted through TLS. This suggests that correlation between understorey structure (and therefore habitat type) and the microtopography of vegetation surfaces may be used for detailed assessment of understorey structural characteristics utilising TLS. In addition to the development of novel analysis methods, new techniques for acquiring TLS data of forest understorey were examined. The use of a standardised methodology for temporal surveying, utilising a common digital terrain model and fixed ground control, as developed here, provides a framework from which further data can be acquired. This approach offers a relatively quick, efficient, non-destructive assessment of temporal change within forests. A novel method of forest survey utilising handheld mobile laser scanning (HMLS) was also tested, showing its potential to complement static TLS surveying by providing increased survey coverage and allowing point cloud processing to be considered for areas which are otherwise difficult to access.

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Mukupa, Wallace. "Change detection and deformation monitoring of concrete structures using terrestrial laser scanning." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/45156/.

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Concrete structures are routinely monitored to detect change and deformation in the field of engineering surveying and other overlapping disciplines such as civil and structural engineering. The monitoring of civil infrastructure is crucial to the safe operation and the longevity of the system. There is growing demand for the development of reliable non-destructive testing techniques for concrete structures in the assessment of the deteriorating condition of infrastructures or in an event of fire-damaged structures. This research investigated the use of terrestrial laser scanning (TLS) for structural health monitoring and the implemented workflow is designed for non full-waveform laser scanner data. Although the use of TLS is not new within the domain of structural health monitoring, the novelty of this research lies in the application of the technology in the specific area of assessing fire-damaged concrete on one hand and the assessment of robust point cloud processing algorithms for precise structural deformation analysis on the other hand. Laser intensity information has become an important object of study in recent years and several studies have shown the potential use of laser intensity data for a great variety of applications such as geomorphology, forestry and glaciology (Holfe and Pfeifer, 2007; Antilla et. al., 2011; Kaasalainen et al., 2011a). Laser intensity information can be used to aid segmentation and classification algorithms alongside geometrical information (Krooks et al., 2013). This evidence for detecting and classifying different materials using the laser intensity values necessitated an investigation into the idea of using the TLS intensity for post fire assessment of concrete. The use of TLS intensity to detect and assess fire-damaged concrete is a new area of research. In terms of the application of TLS for structural change detection and deformation monitoring, TLS is able to provide continuous spatial resolution and reliable 3D information with high redundancy. However, a recent review of studies that have applied TLS for change detection and deformation monitoring of structures has shown that the exploitation of the high data redundancy acquired by TLS is key to achieving good deformation measurement performance with TLS data and that this calls for the development and testing of robust tools. This being the case, several issues are still open to investigation such as rigorous methods of point cloud processing for change detection and deformation analysis. In view of this, the study also aimed at investigating and assessing algorithms for deformation analysis. This thesis presents the work undertaken during the entire period of the research project. The objectives of this research were twofold i.e. detecting and assessing fire-damaged concrete and well as structural deformation monitoring using laser scanning technique. In particular, the technique employed in detecting fire-damaged concrete involved modelling and analysing the laser intensity return. In the case of structural deformation monitoring, the study investigated robust techniques of processing laser scanner data for deformation analysis. This involved assessing the capability of using the multiscale model to model cloud comparison (M3C2) and the iterative similarity registration (ISR) algorithms for processing laser scanner data for deformation analysis. The achieved positive results relating intensity to exposure temperature of concrete demonstrate that laser scanning can be applied to detect and assess fire-damaged concrete and provide an understanding of the condition of concrete in relation to the strength changes of concrete when it is heated to elevated temperatures. In terms of structural monitoring, the study has ascertained that the M3C2 and the ISR algorithms are capable of resolving small scale displacements in the millimetre range which are needed in structural monitoring, due to their robustness.

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Zogg, Hans Martin. "Investigations of high precision terrestrial laser scanning with emphasis on the development of a robust close-range 3D-laser scanning system /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=18013.

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Crabtree, Gärdin David, and Alexander Jimenez. "Optical methods for 3D-reconstruction of railway bridges : Infrared scanning, Close range photogrammetry and Terrestrial laser scanning." Thesis, Luleå tekniska universitet, Byggkonstruktion och brand, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-67716.

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The forecast of the next upcoming years estimates a growth of demand in transport. As the railway sector in Europe has developed over many years, the infrastructure presents performance issues because of, among other factors, asset maintenance activities being difficult and time consuming. There are currently 4000 railway bridges in Sweden managed by Trafikverket which are submitted to inspections at least every six years. The most common survey is done visually to determine the physical and functional condition of the bridges as well as finding damages that may exist on them. Because visual inspection is a subjective evaluation technique, the results of these bridge inspections may vary from inspector to inspector. The data collection is time consuming and written in standard inspection reports which may not provide sufficient visualization of damages. The inspector also needs to move around the bridge at close distance which could lead to unsafe working conditions. 3D modelling technology is becoming more and more common. Methods such as Close Ranged Photogrammetry (CRP) and Terrestrial Laser Scanning (TLS) are starting to be used for architecture and heritage preservation as well as engineering applications. Infrared (IR) scanning is also showing potential in creating 3D models but has yet not been used for structural analysis and inspections. A result from these methods is a point cloud, a 3D representation of a model in points that can be used for creating as-built Building Information Modeling (BIM)-models. In this study, the authors put these three methods to test to see if IR scanning and CRP are suitable ways, such as TLS is, to gather data for 3D-reconstruction of concrete railway bridges in fast, safe and non-disturbing ways. For this, the three technologies are performed on six bridges chosen by Trafikverket. The further aim is to determine if the 3D-reconstructions can be used for acquiring BIM-information to, among other things, create as-built drawings and to perform structural evaluations. As a result from the study, IR scanning and CRP show great potential as well as TLS in 3D-reconstruction of concrete railway bridges in fast, safe and non-disturbing ways. Still, there is a need of development regarding the technologies before we can start to rely on them completely.

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Wang, Zhao. "Real-time updated free station as a georeferencing method in terrestrial laser scanning." Thesis, Högskolan i Gävle, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-9470.

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Georeferencing is an important task in terrestrial laser scanning (TLS) applications. It means transformation of the 3D data (point clouds) into an external coordinate system so that it can be combined with other spatial data. The aim of this study is to investigate the accuracy and precision of real-time updated free station (RUFS) as a georeferencing method in TLS applications, and to evaluate its efficiency. The RUFS is used in total station surveys, implies determination of the instrument position and orientation based on measurements of two or more backsight targets, whose coordinates are determined with Real Time Kinematic (RTK) GNSS. The field surveying was carried out in May and June 2010. A control point was established based on static GNSS measurements in order to have reference data to evaluate the accuracy of station coordinates. Three different configurations of 10 backsight targets were tested: the targets were evenly spread over the sectors of 200 and 100 gon on one arc and 100 gon on two arcs. The measurements were repeated ten times for each configuration. The precision and accuracy of the station position were then derived by processing the surveying data. The results show that with increasing the number of backsight points from 2 to 10, the planimetric precision of the station position improved from 6 to 3 mm; the height precision was at the level of 3−5 mm. The accuracy of the station position improved from 10 to 2 mm in planimetry, and from 28 to 11 mm in height. The time expense for one set of measurements with RUFS was approximately 15 minutes.

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Fan, Lei. "Uncertainty in terrestrial laser scanning for measuring surface movements at a local scale." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/372009/.

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Terrestrial laser scanning (TLS) is a remote sensing tool that can record a large amount of accurate topographical information with a fine spatial resolution over a short period of time. It has been used increasingly for measuring ground surfaces (i.e. topographical survey) and monitoring surface movements, such as those caused by landslides. However, the capability of this technique in these applications has not been fully explored in the literature, and thus forms the focus of this thesis. A quantitative study has been carried out to investigate the major error sources that affect the accuracy of digital elevation models (DEMs) derived from TLS survey data, and the magnitude of deformation that can be detected by repeated TLS surveys, at a local scale. In this research, vegetation-induced elevation errors in TLS measurements and the ways in which they can be minimised have been investigated experimentally. The presence of short vegetation was found to be a significant limiting factor for TLS surveys of terrain surfaces, with the average grass-induced elevation error being roughly 65% of the grass height. A finer resolution scan with a lower incidence angle (greater visibility) can effectively reduce vegetation error, as will scanning the same area from multiple scanner locations. The influence of measurement errors in source data points (or a point cloud) on a triangulated irregular network (TIN) with linear interpolation has been analysed. Based on the law of error propagation, an analytical solution was derived to calculate the error variance at any location within a TIN model, due to vertical and horizontal errors in source data points. For the special case of equal and independent error variances in source data points, the maximum, average and minimum values of propagated error variance within a TIN were found to be equal to unity, a half and a third respectively of the error variance in source data points. Errors in DEMs created from the TLS data points representing four terrain surfaces of different characteristics have been quantified using a statistical resampling method. The results show that terrain surface complexity can considerably affect the accuracy of DEMs. The effects of data point density (equivalent point spacing) on the DEM errors have also been analysed. For the data point spacings (35-100 mm) considered in the analyses, the DEM errors increased almost linearly with increasing data point spacing. The results also show that the DEM errors can be decomposed into two parts: a noise-related part and a data-density dependent part. Repeat TLS surveys of some fixed objects have been carried out, to seek to empirically quantify the georeferencing-induced positional errors involved in repeated TLS surveys. The results indicate that repeated TLS surveys can measure millimetric deformations of smooth surfaces if a high georeferencing accuracy is achieved. The DEM errors, along with the georeferencing-induced positional errors, were used to infer the minimum magnitude of movements that can be measured by multi-temporal TLS surveys of rough terrain surfaces. In the case of the Newbury cutting considered in this study, the minimum level of detection was approximately 20 mm (at a 95% confidence level) for the data point spacing of 35 mm. The findings in this research can aid in assessing the fitness of TLS surveys of terrain surfaces for a particular project, and thus are of use in the survey planning. The methods presented in this thesis can be applied to analyse errors in DEMs for making more meaningful interpretations of DEMs or surface variations derived from repeated TLS surveys.

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Sun, Yanshen. "Evaluating the quality of ground surfaces generated from Terrestrial Laser Scanning (TLS) data." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/90577.

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Researchers and GIS analysts have used Aerial Laser Scanning (ALS) data to generate Digital Terrain Models (DTM) since the 1990s, and various algorithms developed for ground point extraction have been proposed based on the characteristics of ALS data. However, Terrestrial Laser Scanning (TLS) data, which might be a better indicator of ground morphological features under dense tree canopies and more accessible for small areas, have been long ignored. In this research, the aim was to evaluate if TLS data were as qualified as ALS to serve as a source of a DTM. To achieve this goal, there were three steps: acquiring and aligning ALS and TLS of the same region, applying ground filters on both of the data sets, and comparing the results. Our research area was a 100m by 140m region of grass, weeds and small trees along Strouble's Creek on the Virginia Tech campus. Four popular ground filter tools (ArcGIS, LASTools, PDAL, MCC) were applied to both ALS and TLS data. The output ground point clouds were then compared with a DTM generated from ALS data of the same region. Among the four ground filter tools employed in this research, the distances from TLS ground points to the ALS ground surface were no more than 0.06m with standard deviations less than 0.3m. The results indicated that the differences between the ground extracted from TLS and that extracted from ALS were subtle. The conclusion is that Digital Terrain Models (DTM) generated from TLS data are valid.
Master of Science
Elevation is one of the most basic data for researches such as flood prediction and land planning in the field of geography, agriculture, forestry, etc. The most common elevation data that could be downloaded from the internet were acquired from field measurements or satellites. However, the finest grained of that kind of data is 1/3m and errors can be introduced by ground objects such as trees and buildings. To acquire more accurate and pure-ground elevation data (also called Digital Terrain Models (DTM)), Researchers and GIS analysts introduced laser scanners for small area geographical research. For land surface data collection, researchers usually fly a drone with laser scanner (ALS) to derive the data underneath, which could be blocked by ground objects. An alternative way is to place the laser scanner on a tripod on the ground (TLS), which provides more data for ground morphological features under dense tree canopies and better precision. As ALS and TLS collect data from different perspectives, the coverage of a ground area can be different. As most of the ground extraction algorithm were designed for ALS data, their performance on TLS data hasn’t been fully tested yet. Our research area was a 100m by 140m region of grass, weeds and small trees along Strouble’s Creek on the Virginia Tech campus. Four popular ground filter tools (ArcGIS, LASTools, PDAL, MCC) were applied to both ALS and TLS data. The output ground point clouds were then compared with a ground surface generated from ALS data of the same region. Among the four ground filter tools employed in this research, the distances from TLS ground points to the ALS ground surface were no more than 0.06m with standard deviations less than 0.3m. The results indicated that the differences between the ground extracted from TLS and that extracted from ALS were subtle. The conclusion is that Digital Terrain Models (DTM) generated from TLS data are valid.

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Bienert, Anne, Louis Georgi, Matthias Kunz, Hans-Gerd Maas, and Oheimb Goddert von. "Comparison and Combination of Mobile and Terrestrial Laser Scanning for Natural Forest Inventories." Molecular Diversity Preservation International MDPI, 2018. https://tud.qucosa.de/id/qucosa%3A31826.

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Terrestrial laser scanning (TLS) has been successfully used for three-dimensional (3D) data capture in forests for almost two decades. Beyond the plot-based data capturing capabilities of TLS, vehicle-based mobile laser scanning (MLS) systems have the clear advantage of fast and precise corridor-like 3D data capture, thus providing a much larger coverage within shorter acquisition time. This paper compares and discusses advantages and disadvantages of multi-temporal MLS data acquisition compared to established TLS data recording schemes. In this pilot study on integrated TLS and MLS data processing in a forest, it could be shown that existing TLS data evaluation routines can be used for MLS data processing. Methods of automatic laser scanner data processing for forest inventory parameter determination and quantitative structure model (QSM) generation were tested in two sample plots using data from both scanning methods and from different seasons. TLS in a multi-scan configuration delivers very high-density 3D point clouds, which form a valuable basis for generating high-quality QSMs. The pilot study shows that MLS is able to provide high-quality data for an equivalent determination of relevant forest inventory parameters compared to TLS. Parameters such as tree position, diameter at breast height (DBH) or tree height can be determined from MLS data with an accuracy similar to the accuracy of the parameter derived from TLS data. Results for instance in DBH determination by cylinder fitting yielded a standard deviation of 1.1 cm for trees in TLS data and 3.7 cm in MLS data. However, the resolution of MLS scans was found insufficient for successful QSM generation. The registration of MLS data in forests furthermore requires additional effort in considering effects caused by poor GNSS signal.

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Reshetyuk, Yuriy. "Investigation and calibration of pulsed time-of-flight terrestrial laser scanners." Licentiate thesis, Stockholm : Division of Geodesy, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4126.

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Plenner, Sean. "Development and application of a simple terrestrial laser scanner." Thesis, University of Iowa, 2014. https://ir.uiowa.edu/etd/1382.

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Since the texture of surfaces plays a key role in the shaping of many environmental processes, high resolution measurements are important to study these phenomena. Specifically, 3-D point cloud data is desirable to document river shape and evolution, surface roughness, and erosion-sedimentation processes. The best method of obtaining these measurements is using a terrestrial laser scanner. However, these are too expensive for limited-use experiments. Therefore, I developed a simple, affordable, and robust system used to acquire high resolution data relating to hydraulic and fluvial environments.

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Hulumtaye, Kefyalew Yederulh Hulumtaye. "Investigation of the use of Laser Scanning for Deformation Monitoring." Thesis, KTH, Geodesi och geoinformatik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-123800.

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The ability of fast and accurate acquiring of large 3D spatial data is the main benefit for consideration of a terrestrial laser scanner in deformation monitoring. The objective of this paper is to discuss this technique with support of practical experiments performed inside a laboratory. It also includes measuring changes from millimetre to sub millimetre level and a comparison of measurements from a terrestrial laser scanner with measurements of other instruments. Various areas of applications are reviewed. The report discusses a surface modeling method to estimate deformation parameters of objects, such as planar, spherical and cylindrical surface representations. Illustrative numerical examples are performed by simulating randomly generated sample point coordinates for estimation of changes of modeled planar and cylindrical surfaces. The practical experiments were performed using a scan of a carton box, a ball and a rounded paper holder, which correspond to the planar, spherical and cylindrical surfaces, respectively. Independent measurements were performed using a total station and a measuring tape to make a comparison with the scanner measurements. A statistical test was performed independently for the changes obtained from each type of modeled surface in order to check whether the movement is real or due to measurement noises. A significant change of the normal of a plane was detected between epochs, and similar results were obtained from both scanner and total station measurements. The normal of the plane was rotated by between scan epochs. A translation of 3.2 and 3.7 millimetres were detected between scan epochs for the center of the sphere and axis of the cylinder, respectively. Only the scanner data was used in this case. From the scanner measurement changes in radii of the sphere and the cylinder were obtained as 1.6 and 3.1 millimetres, respectively between scan epochs. The measurement of the scanner was verified by performing independent measurements using measuring tape. And hence the change in radii of the sphere and the cylinder were obtained as 2.5 and 4 millimetres, respectively.

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Lobb, Michael Alister. "Developing terrestrial laser scanning of threatened coastal archaeology with special reference to intertidal structures." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/414053/.

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The aim of this thesis is to develop a means of using terrestrial laser scanning to rapidly record coastal and intertidal archaeology within its immediate environs and to use that context to understand its construction and function. Key to this is the underlying concept that structures built to exploit and utilise the resources of the intertidal zone are fully dependant on the dynamics of their immediate landscape. Terrestrial laser scanning provides a level of data not previously gathered in the recording of intertidal sites, allowing a highly detailed recording of complex three dimensional structures to a high level of accuracy, and, through integration with other forms of metric survey, the placement of this information within a wider topographic landscape. The challenges of the intertidal zone hamper traditional archaeological recording techniques, and very often the complexity of structures, subtleties of topography, and distance from the shore can mean that planning of sites ignores the context of the wider landscape. This thesis provides a methodological approach to dealing with these issues, but also looks at how the data generated can go further into answering questions about the interaction of human technology with the dynamics of the landscape. Case studies at a number of sites throughout England and France are presented and used to examine various aspects of the technology and its application to coastal and intertidal archaeology.

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Jaafar, Hasan Abdulhussein. "Detection and localisation of structural deformations using terrestrial laser scanning and Generalised Procrustes Analysis." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/39376/.

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One of the most vital duties for engineers is to preserve life and nature by utilising safe designs that take into account environmental standards and monitoring the performance of structures against design criteria. Furthermore, monitoring can be used to determine any required maintenance of an important structure following a catastrophic event. Numerous different techniques and instruments can be employed for such a purpose with different requirements producing different results. For instance, some techniques need to embed sensors inside the building, such as Geotechnical Sensors. Others can offer high quality, but with a low point density and require fixed stations and targets, like Total Stations (TS). In such cases, the location of deformation tends to be known, such as in dams, bridges, and high-rise buildings. However, this is not always the case where it might be hard to expect deformation location as in the case of historic ruins where each part of the structure could be subject to deformation. The challenge in such case is to detect the deformation without any previous knowledge. Remote Sensing (RS) techniques, such as Digital Photogrammetry, Synthetic Aperture Radar (SAR), Interferometric Synthetic Aperture Radar (InSAR), and Terrestrial Laser Scanner (TLS) can be solutions for such an issue. Interestingly, many researchers are focusing on using TLS for monitoring owing to the great spatial resolution system can offer. However, there are three challenges in using TLS in monitoring: the first one is a huge amount of data and the difficulty of handling it; the second one is the difficulty of comparing between two epochs because observations of TLS are not repeatable; and the third issue is the noise which is attached to the data. The first problem is solved by segmentation and point structure while the second and the third ones still need more investigation, although some interesting researches have been done in this area. The aim of this research is to develop a new approach to detect and localise unpredictable deformation. It is based on TLS measurements and Generalised Procrustes Analysis (GPA) techniques to determine deformation vectors, while boxing structure and F-test are used to detect and localise deformation. In summary, after applying this approach, the whole concerned building is represented as parts, for each of which the displacement vector and the deformation probability are estimated. Ultimately, it is possible to monitor any part through different epochs. In addition, through this technique, it is possible to determine deformations - not just between two epochs, but for sequences of them. This can give more reliable results. Four validation experiments have been conducted. The first test was designed to assess the performance of the developed software and to fix some variables. Therefore, it was based on simulated data with controlled white noise, distributed according to the normal distribution, and simulated deformations. The results of this test revealed the success of the proposed algorithm to detect and to localise deformations. In addition, it showed the success when no deformations exist. Furthermore, optimistically, it could observe deformations with magnitude less than the noise level; however, the probability was only 40%. Correspondingly, real scan data with simulated deformations was used in the second test. The purpose of this test is to examine the performance of the proposed method in case of real errors budget. However, the short range of the test (about 10m), a featureless scanned area (wall only), and scanning from one position for all epochs (no need for registration) can reduce errors to a minimum. Results of this test showed the success of the proposed method to detect and localise deformations. Potentially, it can give indications for areas with deformations less than the noise level. Furthermore, results of the proposed method can be considered better than that of CloudCompare software. The third test was conducted to examine the performance of the proposed technique regarding different materials and textures. For this purpose, the Nottingham Geospatial Building (NGB) was selected with more extensive ranges (between 20-25 m). Similar to the second test, all measurements were taken from the same scanner position. To some extent, the proposed technique succeeded to detect and to localise deformations. However, the researcher does not recommend it for monitoring modern and complicated buildings, instead it has been developed for monitoring historic ruins. Finally, the proposed method was applied on the Bellmanpark Limekiln, Clitheroe, Lancashire monitoring project. This is a live project for Historic England and addresses a historic building that currently has some structural issues. The outcome of the proposed method revealed deformations in the faces South East (SE) and North East (NE). From examining these faces, three deformed areas were found: two in the face SE and one in the face NE, which might cause some cracks appeared in these faces. Alternatively, the CloudCompare software has been employed to detect deformation. Although results coincide with the proposed method for detected deformations, it cannot locate these deformations very well because it diffused over a wide area. In addition, it cannot determine actual directions of the deformations unlike the proposed method.

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Held, Christoph. "Creating 3D models of cultural heritage sites with terrestrial laser scanning and 3D imaging." Master's thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/12076.

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Includes abstract.
Includes bibliographical references.
The advent of terrestrial laser-scanners made the digital preservation of cultural heritage sites an affordable technique to produce accurate and detailed 3D-computermodel representations for any kind of 3D-objects, such as buildings, infrastructure, and even entire landscapes. However, one of the key issues with this technique is the large amount of recorded points; a problem which was even more intensified by the recent advances in laser-scanning technology, which increased the data acquisition rate from 25 thousand to 1 million points per second. The following research presents a workflow for the processing of large-volume laser-scanning data, with a special focus on the needs of the Zamani initiative. The research project, based at the University of Cape Town, spatially documents African Cultural Heritage sites and Landscapes and produces meshed 3D models, of various, historically important objects, such as fortresses, mosques, churches, castles, palaces, rock art shelters, statues, stelae and even landscapes.

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Miller, Jordan Mitchell. "Estimation of individual tree metrics using structure-from-motion photogrammetry." Thesis, University of Canterbury. Geography, 2015. http://hdl.handle.net/10092/11035.

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The deficiencies of traditional dendrometry mean improvements in methods of tree mensuration are necessary in order to obtain accurate tree metrics for applications such as resource appraisal, and biophysical and ecological modelling. This thesis tests the potential of SfM-MVS (Structure-fromMotion with Multi-View Stereo-photogrammetry) using the software package PhotoScan Professional, for accurately determining linear (2D) and volumetric (3D) tree metrics. SfM is a remote sensing technique, in which the 3D position of objects is calculated from a series of photographs, resulting in a 3D point cloud model. Unlike other photogrammetric techniques, SfM requires no control points or camera calibration. The MVS component of model reconstruction generates a mesh surface based on the structure of the SfM point cloud. The study was divided into two research components, for which two different groups of study trees were used: 1) 30 small, potted ‘nursery’ trees (mean height 2.98 m), for which exact measurements could be made and field settings could be modified, and; 2) 35 mature ‘landscape’ trees (mean height 8.6 m) located in parks and reserves in urban areas around the South Island, New Zealand, for which field settings could not be modified. The first component of research tested the ability of SfM-MVS to reconstruct spatially-accurate 3D models from which 2D (height, crown spread, crown depth, stem diameter) and 3D (volume) tree metrics could be estimated. Each of the 30 nursery trees was photographed and measured with traditional dendrometry to obtain ground truth values with which to evaluate against SfM-MVS estimates. The trees were destructively sampled by way of xylometry, in order to obtain true volume values. The RMSE for SfM-MVS estimates of linear tree metrics ranged between 2.6% and 20.7%, and between 12.3% and 47.5% for volumetric tree metrics. Tree stems were reconstructed very well though slender stems and branches were reconstructed poorly. The second component of research tested the ability of SfM-MVS to reconstruct spatially-accurate 3D models from which height and DBH could be estimated. Each of the 35 landscape trees, which varied in height and species, were photographed, and ground truth values were obtained to evaluate against SfM-MVS estimates. As well as this, each photoset was thinned to find the minimum number of images required to achieve total image alignment in PhotoScan and produce an SfM point cloud (minimum photoset), from which 2D metrics could be estimated. The height and DBH were estimated by SfM-MVS from the complete photosets with RMSE of 6.2% and 5.6% respectively. The height and DBH were estimated from the minimum photosets with RMSE of 9.3% and 7.4% respectively. The minimum number of images required to achieve total alignment was between 20 and 50. There does not appear to be a correlation between the minimum number of images required for alignment and the error in the estimates of height or DBH (R2 =0.001 and 0.09 respectively). Tree height does not appear to affect the minimum number of images required for image alignment (R 2 =0.08).

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Smith, Zachary Joseph. "Mapping the Spatial Movements, Behaviors, and Interactions of Captive Orangutans using Terrestrial Laser Scanning and GIS." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5312.

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Five captive Bornean orangutans (Pongo pygmaeus) were observed in order to better understand their spatial selection, behavior, and interaction with their environment and each other. A newly introduced adult male's interactions with a female group containing two adults, one adolescent, and one juvenile, was documented. Visual observations were performed to document individual behaviors, along with any interactions with silvery langur monkeys, public crowd levels, temperature, and enrichment props. Methods included 15 observation periods, 0.5-3 hours in length each, during which behaviors were verbally and visually confirmed using a HD video camera. Spatial locations of each individual were recorded every three minutes during each observation period. The orangutan enclosure was measured and mapped using terrestrial laser scanning (TLS), and observed behaviors and spatial locations were georeferenced to the resulting 3D model depicting the exhibit. Results were summarized as time-activity budgets and were geo-visualized using 3D plots and density maps. This research demonstrated how the application of spatiotemporal and behavioral analysis coupled with TLS and three-dimensional modelling can be used to better study captive primates. These types of studies are important as zoos increasingly become home to great ape species.

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Swetnam, Tyson L., Jeffrey K. Gillan, Temuulen T. Sankey, Mitchel P. McClaran, Mary H. Nichols, Philip Heilman, and Jason McVay. "Considerations for Achieving Cross-Platform Point Cloud Data Fusion across Different Dryland Ecosystem Structural States." FRONTIERS MEDIA SA, 2018. http://hdl.handle.net/10150/626554.

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Remotely sensing recent growth, herbivory, or disturbance of herbaceous and woody vegetation in dryland ecosystems requires high spatial resolution and multi-temporal depth. Three dimensional (3D) remote sensing technologies like lidar, and techniques like structure from motion (SfM) photogrammetry, each have strengths and weaknesses at detecting vegetation volume and extent, given the instrument's ground sample distance and ease of acquisition. Yet, a combination of platforms and techniques might provide solutions that overcome the weakness of a single platform. To explore the potential for combining platforms, we compared detection bias amongst two 3D remote sensing techniques (lidar and SfM) using three different platforms [ground-based, small unmanned aerial systems (sUAS), and manned aircraft]. We found aerial lidar to be more accurate for characterizing the bare earth (ground) in dense herbaceous vegetation than either terrestrial lidar or aerial SfM photogrammetry. Conversely, the manned aerial lidar did not detect grass and fine woody vegetation while the terrestrial lidar and high resolution near-distance (ground and sUAS) SfM photogrammetry detected these and were accurate. UAS SfM photogrammetry at lower spatial resolution under-estimated maximum heights in grass and shrubs. UAS and handheld SfM photogrammetry in near-distance high resolution collections had similar accuracy to terrestrial lidar for vegetation, but difficulty at measuring bare earth elevation beneath dense herbaceous cover. Combining point cloud data and derivatives (i.e., meshes and rasters) from two or more platforms allowed for more accurate measurement of herbaceous and woody vegetation (height and canopy cover) than any single technique alone. Availability and costs of manned aircraft lidar collection preclude high frequency repeatability but this is less limiting for terrestrial lidar, sUAS and handheld SfM. The post-processing of SfM photogrammetry data became the limiting factor at larger spatial scale and temporal repetition. Despite the utility of sUAS and handheld SfM for monitoring vegetation phenology and structure, their spatial extents are small relative to manned aircraft.

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Schilling, Anita. "Automatic Retrieval of Skeletal Structures of Trees from Terrestrial Laser Scanner Data." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-155698.

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Research on forest ecosystems receives high attention, especially nowadays with regard to sustainable management of renewable resources and the climate change. In particular, accurate information on the 3D structure of a tree is important for forest science and bioclimatology, but also in the scope of commercial applications. Conventional methods to measure geometric plant features are labor- and time-intensive. For detailed analysis, trees have to be cut down, which is often undesirable. Here, Terrestrial Laser Scanning (TLS) provides a particularly attractive tool because of its contactless measurement technique. The object geometry is reproduced as a 3D point cloud. The objective of this thesis is the automatic retrieval of the spatial structure of trees from TLS data. We focus on forest scenes with comparably high stand density and with many occlusions resulting from it. The varying level of detail of TLS data poses a big challenge. We present two fully automatic methods to obtain skeletal structures from scanned trees that have complementary properties. First, we explain a method that retrieves the entire tree skeleton from 3D data of co-registered scans. The branching structure is obtained from a voxel space representation by searching paths from branch tips to the trunk. The trunk is determined in advance from the 3D points. The skeleton of a tree is generated as a 3D line graph. Besides 3D coordinates and range, a scan provides 2D indices from the intensity image for each measurement. This is exploited in the second method that processes individual scans. Furthermore, we introduce a novel concept to manage TLS data that facilitated the researchwork. Initially, the range image is segmented into connected components. We describe a procedure to retrieve the boundary of a component that is capable of tracing inner depth discontinuities. A 2D skeleton is generated from the boundary information and used to decompose the component into sub components. A Principal Curve is computed from the 3D point set that is associated with a sub component. The skeletal structure of a connected component is summarized as a set of polylines. Objective evaluation of the results remains an open problem because the task itself is ill-defined: There exists no clear definition of what the true skeleton should be w.r.t. a given point set. Consequently, we are not able to assess the correctness of the methods quantitatively, but have to rely on visual assessment of results and provide a thorough discussion of the particularities of both methods. We present experiment results of both methods. The first method efficiently retrieves full skeletons of trees, which approximate the branching structure. The level of detail is mainly governed by the voxel space and therefore, smaller branches are reproduced inadequately. The second method retrieves partial skeletons of a tree with high reproduction accuracy. The method is sensitive to noise in the boundary, but the results are very promising. There are plenty of possibilities to enhance the method’s robustness. The combination of the strengths of both presented methods needs to be investigated further and may lead to a robust way to obtain complete tree skeletons from TLS data automatically
Die Erforschung des ÖkosystemsWald spielt gerade heutzutage im Hinblick auf den nachhaltigen Umgang mit nachwachsenden Rohstoffen und den Klimawandel eine große Rolle. Insbesondere die exakte Beschreibung der dreidimensionalen Struktur eines Baumes ist wichtig für die Forstwissenschaften und Bioklimatologie, aber auch im Rahmen kommerzieller Anwendungen. Die konventionellen Methoden um geometrische Pflanzenmerkmale zu messen sind arbeitsintensiv und zeitaufwändig. Für eine genaue Analyse müssen Bäume gefällt werden, was oft unerwünscht ist. Hierbei bietet sich das Terrestrische Laserscanning (TLS) als besonders attraktives Werkzeug aufgrund seines kontaktlosen Messprinzips an. Die Objektgeometrie wird als 3D-Punktwolke wiedergegeben. Basierend darauf ist das Ziel der Arbeit die automatische Bestimmung der räumlichen Baumstruktur aus TLS-Daten. Der Fokus liegt dabei auf Waldszenen mit vergleichsweise hoher Bestandesdichte und mit zahlreichen daraus resultierenden Verdeckungen. Die Auswertung dieser TLS-Daten, die einen unterschiedlichen Grad an Detailreichtum aufweisen, stellt eine große Herausforderung dar. Zwei vollautomatische Methoden zur Generierung von Skelettstrukturen von gescannten Bäumen, welche komplementäre Eigenschaften besitzen, werden vorgestellt. Bei der ersten Methode wird das Gesamtskelett eines Baumes aus 3D-Daten von registrierten Scans bestimmt. Die Aststruktur wird von einer Voxelraum-Repräsentation abgeleitet indem Pfade von Astspitzen zum Stamm gesucht werden. Der Stamm wird im Voraus aus den 3D-Punkten rekonstruiert. Das Baumskelett wird als 3D-Liniengraph erzeugt. Für jeden gemessenen Punkt stellt ein Scan neben 3D-Koordinaten und Distanzwerten auch 2D-Indizes zur Verfügung, die sich aus dem Intensitätsbild ergeben. Bei der zweiten Methode, die auf Einzelscans arbeitet, wird dies ausgenutzt. Außerdem wird ein neuartiges Konzept zum Management von TLS-Daten beschrieben, welches die Forschungsarbeit erleichtert hat. Zunächst wird das Tiefenbild in Komponenten aufgeteilt. Es wird eine Prozedur zur Bestimmung von Komponentenkonturen vorgestellt, die in der Lage ist innere Tiefendiskontinuitäten zu verfolgen. Von der Konturinformation wird ein 2D-Skelett generiert, welches benutzt wird um die Komponente in Teilkomponenten zu zerlegen. Von der 3D-Punktmenge, die mit einer Teilkomponente assoziiert ist, wird eine Principal Curve berechnet. Die Skelettstruktur einer Komponente im Tiefenbild wird als Menge von Polylinien zusammengefasst. Die objektive Evaluation der Resultate stellt weiterhin ein ungelöstes Problem dar, weil die Aufgabe selbst nicht klar erfassbar ist: Es existiert keine eindeutige Definition davon was das wahre Skelett in Bezug auf eine gegebene Punktmenge sein sollte. Die Korrektheit der Methoden kann daher nicht quantitativ beschrieben werden. Aus diesem Grund, können die Ergebnisse nur visuell beurteiltwerden. Weiterhinwerden die Charakteristiken beider Methoden eingehend diskutiert. Es werden Experimentresultate beider Methoden vorgestellt. Die erste Methode bestimmt effizient das Skelett eines Baumes, welches die Aststruktur approximiert. Der Detaillierungsgrad wird hauptsächlich durch den Voxelraum bestimmt, weshalb kleinere Äste nicht angemessen reproduziert werden. Die zweite Methode rekonstruiert Teilskelette eines Baums mit hoher Detailtreue. Die Methode reagiert sensibel auf Rauschen in der Kontur, dennoch sind die Ergebnisse vielversprechend. Es gibt eine Vielzahl von Möglichkeiten die Robustheit der Methode zu verbessern. Die Kombination der Stärken von beiden präsentierten Methoden sollte weiter untersucht werden und kann zu einem robusteren Ansatz führen um vollständige Baumskelette automatisch aus TLS-Daten zu generieren

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Henning, Jason Gregory. "Modeling Forest Canopy Distribution from Ground-Based Laser Scanner Data." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/28431.

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A commercially available, tripod mounted, ground-based laser scanner was used to assess forest canopies and measure individual tree parameters. The instrument is comparable to scanning airborne light detection and ranging (lidar) technology but gathers data at higher resolution over a more limited scale. The raw data consist of a series of range measurements to visible surfaces taken at known angles relative to the scanner. Data were translated into three dimensional (3D) point clouds with points corresponding to surfaces visible from the scanner vantage point. A 20 m x 40 m permanent plot located in upland deciduous forest at Coweeta, NC was assessed with 41 and 45 scans gathered during periods of leaf-on and leaf-off, respectively. Data management and summary needs were addressed, focusing on the development of registration methods to align point clouds collected from multiple vantage points and minimize the volume of the plot canopy occluded from the scanner's view. Automated algorithms were developed to extract points representing tree bole surfaces, bole centers and ground surfaces. The extracted points served as the control surfaces necessary for registration. Occlusion was minimized by combining aligned point clouds captured from multiple vantage points with 0.1% and 0.34% of the volume scanned being occluded from view under leaf-off and leaf-on conditions, respectively. The point cloud data were summarized to estimate individual tree parameters including diameter at breast height (dbh), upper stem diameters, branch heights and XY positions of trees on the plot. Estimated tree positions were, on average, within 0.4 m of tree positions measured independently on the plot. Canopy height models, digital terrain models and 3D maps of the density of canopy surfaces were created using aligned point cloud data. Finally spatially explicit models of the horizontal and vertical distribution of plant area index (PAI) and leaf area index (LAI) were generated as examples of useful data summaries that cannot be practically collected using existing methods.
Ph. D.

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Lim, Kwanthar. "Semi-automated registration with direct linear transformation and quality evaluation of digital photogrammetry and terrestrial laser scanning." Thesis, Curtin University, 2012. http://hdl.handle.net/20.500.11937/2592.

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Photogrammetry and Laser Scanning can be used to complement one another, during instances where digital images are taken of the object of interest with the intention to merge the 3D data and image in order to reconstruct photorealistic virtual models with photo quality and metric realism. Laser scanning acquires 3D data points and intensity information of objects but is unable to directly obtain photorealistic colour in most cases. To get photorealistic colour, some laser scanners come with an onboard camera, or alternatively a separate camera is used, and registration is required for both cases. One example uses a specially designed camera mounting for the laser scanner and another is to transfer colour information from 2D images captured from near the scanner to the 3D points using close-range photogrammetry. Currently limited methods exist for the registration of the data from multiple-sensors. This research outlines the evaluation and semi-automated registration of a single colour image to laser scanning point cloud data, using the canonical transformation and Direct Linear Transformation (DLT) methods for registration.The method presented in this thesis is to directly reconstruct three dimensional data from a single image with the assistance of estimated depth information. Laser scanning point cloud information is used to supplement the recovery of the estimated depth information, which is then assigned to the image data. Two primary aspects for this research are (1) the Synthetic Camera Image, following on from previous work reported in the literature on utilising synthetic imagery created from point-clouds, and (2) the Direct Linear Transformation model, which is used to provide the transformation parameters between the 2D and 3D datasets.Synthetic datasets were used to provide an indication of expected results in terms of range, incidence angle and image resolution. The image resolution is an important factor to consider. It should be as high as possible as it affects the outcome of precision. Testing with real data, the proposed method resulted in a precision of 2 mm for the data of a model T-Rex dinosaur dataset, and 19mm for a typical indoor scene. The variations in precision levels are due to different values for range, incidence angle and image resolution. Overall the results achieved the expectations producing a colour point cloud with metric assessment.

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Almeida, Gustavo José Ferreira de. "Uso do laser scanner terrestre na estimativa de parâmetros biométricos em povoamentos florestais." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/11/11150/tde-02032018-094924/.

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A quantificação de recursos florestais é usada para fins diversos nas ciências naturais, e depende da obtenção de dados de campo de forma precisa e rápida, e o inventário florestal tem se valido principalmente de trabalho humano manual para este fim. A tecnologia LiDAR, baseada em sistemas a laser, permite a coleta desses dados por meio da representação tridimensional do ambiente e a geração de informações espacialmente precisas dos objetos que o compõe. O sistema de varredura laser terrestre (terrestrial laser scanning - TLS) aplica essa tecnologia sob abordagem terrestre, e assim pode ser usada na representação 3D de florestas e ambientes naturais. Devido a crescente número de estudos nesse tópico atualmente o sistema TLS é capaz de fornecer métricas florestais básicas com elevada exatidão, como densidade de plantio e diâmetro à altura do peito, além de informações não obtidas pelo inventário florestal padrão, como estimativa da biomassa e índice de área foliar, entre outros. Este trabalho tem por objetivo a avalição da capacidade do sistema TLS em fornecer com exatidão métricas de árvores individuais selecionadas em dois povoamentos florestais localizados no sudeste do Brasil. Árvores de Eucalyptus sp. (n = 6) e Pinus elliottii var. elliottii (n = 5) foram submetidas à varredura e os valores obtidos pelo mapeamento 3D foram comparados com dados medidos em campo manualmente. Os resultados encontrados mostram que o algoritmo empregado na filtragem dos troncos foi eficiente no isolamento dos fustes de árvores individuais até a altura total das árvores amostradas, enquanto que o algoritmo para modelagem do tronco filtrado foi capaz de fornecer medidas de diâmetro até 50% da altura total das amostras. A exatidão das medidas de DAP pelos dados TLS foi de 0,91 cm e 2,77 cm (REQM) para Eucalyptus e Pinus, respectivamente. Os diâmetros ao longo do fuste tiveram mais exatidão no Eucalyptus (REQM = 2,75 cm e r = 0,77) do que no Pinus (REQM = 3,62 cm e r = 0,86), resultados condizentes com os encontrados em literatura. A exatidão da estimativa dos diâmetros diminuiu ao longo do fuste. O autor sugere que a influência de vento forte no momento da varredura pode ter interferido na qualidade das nuvens de pontos em relação a ruídos e na exatidão dos modelos de obtenção de diâmetros. A partir destes resultados conclui-se que, para as características ambientais e parâmetros de varreduras apresentados, o sistema TLS foi capaz de fornecer dados com exatidão aceitável, e mais estudos devem ser conduzidos buscando o entendimento e mitigação de efeitos que podem dificultar a obtenção de dados precisos nos estratos superiores do dossel florestal.
Forest resources assessment is used for diverse purposes on natural sciences, and relies on field data acquisition in fast and precise ways, and forest inventory has been relying mainly on manual human labor for that. LiDAR technology, which is based on a laser system, allows for these data acquisition through 3D representation of surroundings and the generation of espacially precise information about the objetcs within. Terrestrial laser scanning - TLS - applies this technology in a land approach, thus it can be used on the 3D representation of forests and natural scenes. Due to increasing number of studies on this subject nowadays TLS system is capable of giving basic forest metrics with high precision, as for plant density and diameter at breast height, besides information not obtained by standard inventory procedures, as biomass estimation and leaf área index, among others. This work aims the assessment of TLS capability on giving precise metrics of individual trees located at two forest stands in southeastern Brazil. Trees of Eucalyptus sp. (n = 6) and Pinus elliottii var. elliottii (n = 5) were scanned and the numbers obtained by 3D mapping were compared to manually measured field data. The results found show that the algorithms used on trunk filtration were efficient on individual trees stem isolation until total height of measured trees, while the trunk modelling algorithm was capable of giving diameters until 50% of samples total height. The precision of DBH measurements by TLS data was 0,91 cm and 2,77 cm (RMSE) for Eucalyptus and Pinus, respectivelly. Diameters along the stem were more preciselly estimated for Eucalytus trees (RMSE = 2,75 cm and r = 0,77) than for Pinus trees (RMSE = 3,62 cm and r = 0,86), results consistente with literature. The precision of diameters estimation diminished along the stem. The author suggests that the influence of intense wind by the time of scanning can have interfered on cloud point quality in the terms of noises and thus on the precision of diameter estimation modelling. From these results one can conclude that, considering the environmental aspects and scanning parameters presented, TLS system was capable on giving data with acceptable precision, and more studies must be carried searching for understanding and mitigation of effects that can difficult precise data acquisition on upper forest strata.

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Persson, Mattias. "Terrester laserskanning eller totalstation : – en jämförelse vid inmätning i stadsmiljö." Thesis, Karlstad University, Faculty of Social and Life Sciences, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-1819.

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Den nya mätningstekniken på marknaden kallas terrester laserskanning. Tekniken bygger på att ett instrument, monterat på ett stativ, sänder ut en laserstråle vilken avlänkas i vertikalled av en spegel samtidigt som det roterar. Laserstrålen reflekteras mot de objekt som befinner sig inom laserskannerns synfält och resulterar i ett punktmoln. Punktmolnet innehåller ofta flera miljoner punkter vilka alla erhåller xyz-koordinater. Tekniken har visat sig lämplig vid dokumentation av byggnader och vid modellering samt kartläggning av industrier och tunnelbyggen.

Denna studie har genomförts på Sweco VBB i Karlstad i syfte att ta reda på hur lämplig terrester laserskanning är vid vardaglig inmätning och kartering av objekt i stadsmiljö. Metoden har jämförts med traditionell inmätning med totalstation utifrån ett antal frågeställningar. I studien laserskannades två korsningar i Vasastaden, Stockholm. Instrumentet som användes var en IMAGER 5006 av märket Zoller+Fröhlich. De totalt sex stycken skanningarna resulterade i punktmoln vilka georefererades genom att måltavlor mättes in med totalstation. Efterbearbetningen bestod av registrering, redigering och reducering av punktmolnen. Genom manuell tolkning av punktmolnen och med hjälp av verktyget Virtual Surveyor i Leica Geosystems programvara Cyclone, kunde olika objekt mätas in och kartläggning av de båda korsningarna ske.

En generell jämförelse mellan terrester laserskanning och totalstation visar att laserskanning är en snabb metod som ger stora mängder data med hög detaljrikedom, medger en större säkerhet i fält och ger enorma möjligheter för visualisering, modellering och skapande av terrängmodeller. Laserskanning är dock en dyr metod som ger en något sämre noggrannhet och som ännu inte klarar att mäta sträckor över hundra meter. Metoden kräver också totalstation (eller GPS) för georeferering. Studien har också visat att tidsvinsten som uppkommer i fält förloras genom tidsödande efterbearbetning och manuell tolkning av punktmolnet. Trots detta använder idag ett flertal företag denna metod vid inmätning. Slutsatserna pekar främst på att laserskanning som inmätningsmetod lämpar sig bäst över små områden där antalet objekt är högt och där säkerheten i fält är viktig. Dock ses metoden mer som ett komplement till totalstationen genom de möjligheter som erbjuds via visualisering och modellering och därmed inte en ersättare för den senare.

A new technique for surveying is the terrestrial laser scanning. The technique is based on an instrument, mounted on a tripod, emitting a laser pulse which is vertically deflected by a mirror while rotating. The laser pulse is reflected by the objects within the field of view of the laser scanner. The laser scan results in a point cloud most often containing several millions of points which all have XYZ-coordinates. The technique has proven its benefits when documenting buildings, modelling and surveying of industries and tunnels.

This study has been carried out at Sweco VBB in Karlstad in purpose of finding out how suitable terrestrial laser scanning is for everyday surveying in urban environment. The method has been compared with traditional surveying with total station from a number of questions. In the study two crossings in Vasastaden, Stockholm, were scanned. The instrument used was an IMAGER 5006 from Zoller+Fröhlich. The 6 scannings resulted in point clouds which were georeferenced by using targets and a total station. The post processing consisted of registering, editing and reducing the point clouds. Through manual interpretation of the point clouds and by using the tool Virtual Surveyor in the program Cyclone by Leica Geosystems it was possible to survey different objects at the crossings.

A general comparison between terrestrial laser scanning and total station shows that laser scanning is a rapid method producing large amounts of data with a high level of details, allows higher security in field and gives enormous possibilities for visualisation, modelling and creating of terrain models. However, laser scanning is an expensive method which gives a slightly lower accuracy and yet cannot be used for longer distances. The method also demands total station (or GPS) for georeferencing. The study has also shown that the saving of time in field is lost by time consuming post processing and manual interpretation of the point cloud. Nonetheless this method is used by several companies for everyday surveying. The conclusions advert mostly that laser scanning is best suitable for small areas where the number of objects is high and where security in field is important. Nevertheless, the method should be seen more as a compliment to the total station because of the possibilities offered by visualisation and modelling and therefore not as a replacement for the latter.

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Monsalve, Juan J. "Integrating Laser Scanning with Discrete Element Modeling for Improving Safety in Underground Stone Mines." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/90659.

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According to the Mine Health and Safety Administration (MSHA), between 2006 and 2016, the underground stone mining industry had the highest fatality rate in 4 out of 10 years, compared to any other type of mining in the United States. Additionally, the National Institute for Occupational Safety and Health (NIOSH) stated that structurally controlled instability is a predominant failure mechanism in underground limestone mines. This type of instability occurs when the different discontinuity sets intercept with each other forming rock blocks that displace inwards the tunnel as the excavation takes place, posing a great hazard for miners and overall mine planning. In recent years, Terrestrial laser scanning (TLS) has been used for mapping and characterizing fractures present in a rock mass. TLS is a technology that allows to generate a three-dimensional multimillion point cloud of a scanned area. In addition to this, the advances in computing power throughout the past years, have allowed numerical modeling codes to represent more realistically the behavior of a fractured rock masses. This work presents and implements a methodology that integrates laser scanning technology along with Discrete Element Modeling as tools for characterizing, preventing, and managing structurally controlled instability that may affect large-opening underground mines. The stability of an underground limestone mine that extracts a dipping ore body with a room and pillar (and eventual stoping) mining method is analyzed with this approach. While this methodology is proposed based on a specific case study that does not meet the requirements to be designed with current NIOSH published guidelines, this process proposes a general methodology that can be applied in any mine experiencing similar failure mechanisms, considering site-specific conditions. The aim of this study is to ensure the safety of mine workers and to reduce accidents that arise from ground control issues. The results obtained from this methodology allowed us to generate Probability Density Functions to estimate the probability of rock fall in the excavations. These models were also validated by comparing the numerical model results with those obtained from the laser scans.
M.S.
According to the Mine Health and Safety Administration (MSHA), between 2006 and 2016, the underground stone mining industry had the highest fatality rate in 4 out of 10 years, compared to any other type of mining in the United States. Additionally, the National Institute for Occupational Safety and Health (NIOSH) stated that structurally controlled instability is one of the main causes of rock falls in underground limestone mines. This type of instability occurs when the fractures present in the rock mass intercept each other forming rock blocks that displace into the tunnel as the excavation takes place and poses a great hazard for miners. In recent years, Terrestrial laser scanning (TLS) has been used for mapping and characterizing fractures present in a rock mass. TLS is a technology that allows to generate a three-dimensional multimillion point cloud of a scanned area. In addition to this, the advances in computing power throughout the past years, have allowed simulation softwares such as the Discrete Element Model (DEM) to represent more realistically the behavior of a fractured rock mass under excavation. The aim of this work was to develop and evaluate a methodology that could complement already exisiting design guidelines that may not apply to all kind of underground mines. The presented methodology evaluates rock failure due to presence of discontinuites, through the integration of TLS with DEM and considers site specific conditions. An area of a case study mine was assessed with this methodology, where several laser scans were performed. Information extracted from this laser scans was used to simulate the response of the rock mass under excavation by running Discrete Element Numerical Models. Results from these models allowed us to estimate the probability of rock failure in the analized areas. These, rock block failure probability estimations provide engineers a tool for characterizing, preventing, and managing structurally controlled instability, and ultimately improving workers safety.

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Moussa, Wassim [Verfasser], and Dieter [Akademischer Betreuer] Fritsch. "Integration of digital photogrammetry and terrestrial laser scanning for cultural heritage data recording / Wassim Moussa. Betreuer: Dieter Fritsch." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2014. http://d-nb.info/105038900X/34.

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Hoffmeister, Dirk Verfasser], Georg [Akademischer Betreuer] [Bareth, and Helmut [Akademischer Betreuer] Brückner. "Feasibility studies of terrestrial laser scanning in Coastal Geomorphology, Agronomy, and Geoarchaeology / Dirk Hoffmeister. Gutachter: Georg Bareth ; Helmut Brückner." Köln : Universitäts- und Stadtbibliothek Köln, 2013. http://d-nb.info/1048428486/34.

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Wujanz, Daniel [Verfasser], Frank [Akademischer Betreuer] Neitzel, Frank [Gutachter] Neitzel, Ingo [Gutachter] Neumann, and Roderik [Gutachter] Lindenbergh. "Terrestrial laser scanning for geodetic deformation monitoring / Daniel Wujanz ; Gutachter: Frank Neitzel, Ingo Neumann, Roderik Lindenbergh ; Betreuer: Frank Neitzel." Berlin : Technische Universität Berlin, 2016. http://d-nb.info/1156274893/34.

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37

Hoffmeister, Dirk [Verfasser], Georg [Akademischer Betreuer] Bareth, and Helmut [Akademischer Betreuer] Brückner. "Feasibility studies of terrestrial laser scanning in Coastal Geomorphology, Agronomy, and Geoarchaeology / Dirk Hoffmeister. Gutachter: Georg Bareth ; Helmut Brückner." Köln : Universitäts- und Stadtbibliothek Köln, 2013. http://nbn-resolving.de/urn:nbn:de:hbz:38-54972.

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38

Seidel, Dominik [Verfasser], Christoph [Akademischer Betreuer] Leuschner, Christoph [Akademischer Betreuer] Kleinn, and Stefan [Akademischer Betreuer] Fleck. "Terrestrial laser scanning : applications in forest ecological research / Dominik Seidel. Gutachter: Christoph Leuschner ; Christoph Kleinn ; Stefan Fleck. Betreuer: Christoph Leuschner." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2011. http://d-nb.info/1043612734/34.

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Larsson, Oskar, and Jacob Hallberg. "Vägmodellering baserad på laserskanning för virtuella fordonssimuleringar." Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-88965.

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För att kunna konkurrera inom dagens fordonsindustri krävs effektiv produktutveckling. Det är under designprocessen som det finns störst möjlighet att påverka slutprodukten till det bättre. Ett sätt att åstadkomma effektivare produktutveckling är att tillämpa ny teknik. För att generera digitaliserade vägmodeller som används i simuleringar kan laserskanning appliceras. I dessa simuleringar kan fordonen testköras virtuellt och därigenom förkorta dimensioneringsprocessen. Laserskanning av kuperad terräng är komplex och därför saknas det underlag av kuperade testbanor i simuleringar. Denna studie syftar till att presentera olika laserskanningstekniker samt att utöka underlaget för virtuella simuleringar inom dimensioneringsprocessen av dumprar. Målet med arbetet är att skapa virtuella vägsektioner som kan användas i simuleringsmodeller. Tre huvudtekniker inom laserskanning presenteras i teorikapitlet. Vidare har terrest laserskanning utförts på Volvos testbana i Målajord och med skanningsdata som underlag har en vägmodell som kan användas i fordonssimuleringar skapats i Matlab. Vägmodellen som skapats representerar väl den verkliga körbanan, vilket indikerar att terrest laserskanning är en väl fungerande metod för detta ändamål.
Product development is necessary to compete in today´s vehicle industry. During the design process the largest possibility to affect the end product to the better exists. One way to achieve product development is to apply new technology. Through application of terrestrial laser scanning digitalized road models can be achieved and be used in simulations. In these simulations, vehicles can virtually do a trial run and thereby shorten the dimensionprocess. Laser scanning of hilly terrain is complex and therefore groundwork of hilly roadways in simulations is missing. This study refers to present different types of laser scanning methods and expand the groundwork for virtual simulations in the dimensionprocess of dumpers. The vision is to create virtual roadways which can be used in simulation models. Three main techniques of laser scanning are presented in the theory chapter. Further on terrestrial laser scanning has been used on Volvos test track in Målajord and with this scanning data as groundwork a road model, which can be used in vehicle simulations, has been created in Matlab. The road model is well representing the real roadway, which indicates that terrestrial laser scanning is a well working method for this purpose.

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Wilkinson, Maxwell. "The use of Terrestrial Laser Scanning in characterizing active tectonic processes from postseismic slip to the long term growth of normal faults." Thesis, Durham University, 2012. http://etheses.dur.ac.uk/5573/.

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This thesis investigates two main hypotheses regarding uncertainty in the measurement of paleoseismic offsets used to estimate fault activity and paleoearthquake magnitudes on normal faults: (1) That variations in fault geometry have a significant effect on throw-rates and fault offsets; and (2) that postseismic deformation can be a significant component of the total fault slip for moderate magnitude earthquakes. These hypotheses are tested using high resolution terrestrial laser scan datasets of normal fault topographic offsets and surface ruptures. The first hypothesis is addressed by studying the crustal scale Campo Felice active normal fault in the Central Apennines, Italy. Variation in throw-rate along strike since the last glacial maximum (15 ka ±3) is measured from an offset periglacial surface at two hundred and fifty sites using cross sectional data derived from a high resolution terrestrial laser scan (TLS) dataset. The measurements are used to create a detailed throw-rate profile. Field measurements of fault geometry (strike, dip and kinematic slip direction) are also gathered. Variation in fault throw-rate is found to correlate with fault strike. A study of weathered band thickness on the exposed Miocene limestone bedrock fault scarp, thought to have been created by single past slip events on the fault also appears to correlate with fault strike. A strain-rate profile is calculated using the throw-rate profile and the field measurements of kinematic slip. In contrast to throw-rate, strainrate is independant of changes in fault strike and dip. It is suggested that strain-rate in comparison to throw-rate provides a more robust measure of fault activity as it is unaffected by changes in fault geometry. The outcome of this study is that paleoseismic studies on active faults should take into account fault geometry before choosing sites which may have anomalously high or low paleoseismic offsets. Fault geometry introduces significant uncertainty into the estimation of inferred paleoearthquake magnitudes from paleoseismic offsets and hence seismic hazard analysis. The second hypothesis is addressed through the study of near-field postseismic deformation (surface rupture afterslip) following the 6th April 2009 6.3 Mw L’Aquila earthquake, created by slip on the Paganica normal fault in the Central Italian Apennines. A novel use of TLS technology allowed the postseismic deformation at four sites along the L’Aquila surface rupture to be measured between 8 – 126 days after the earthquake. Complimentary measurements of postseismic deformation at a fifth site using a robotic total station were combined with the TLS datasets to describe the along strike variation in postseismic deformation. The near-field postseismic deformation measured occurred mostly in the immediate hangingwall of the surface rupture and increased with decreasing rate over time. The postseismic deformation measured is comparable to theoretical and empirical models which have been used to describe afterslip for previous earthquakes. The magnitude of near-field postseismic deformation was up to 60% that of the coseismic offset in the near-field and suggests that postseismic deformation can form a significant component of paleoseismic offsets of moderate magnitude. Postseismic deformation was also found to be greatest above regions of the fault zone where a high coseismic slip gradient existed, suggesting that postseismic deformation occurs at the periphery of the coseismic slip patch within the fault zone. Regression relationships which relate surface offset to moment magnitude are populated by field observations of surface offsets where earthquake magnitude is known. These regression relationships are then used to infer paleoearthquake magnitudes from paleoseismic offsets. The field studies used to populate regression relationships do not routinely take into account the potential effects of fault geometry and significant postseismic slip. As a result paleoearthquake magnitudes inferred from such regression relationships are maybe over estimated. It is suggested that future regression relationships of surface offset and moment magnitude should factor in the effects of fault geometry and postseismic deformation in order to produce a relationship in which surface offset (both coseismic and postseismic) is described for a range of magnitudes and, where possible, any local effects of fault geometry are removed from the input dataset. The production of such a relationship will allow paleoseismologists to measure combined coseismic and postseismic offsets from field studies and to infer paleoearthquake magnitude with decreased uncertainty.

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Crespo, Peremarch Pablo. "Processing and analysis of airborne fullwaveform laser scanning data for the characterization of forest structure and fuel properties." Doctoral thesis, Universitat Politècnica de València, 2020. http://hdl.handle.net/10251/153715.

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[ES] Esta tesis aborda el desarrollo de métodos de procesado y análisis de datos ALSFW para la caracterización de la estructura vertical del bosque y, en particular, del sotobosque. Para responder a este objetivo general, se establecieron seis objetivos específicos: En primer lugar, se analiza la influencia de la densidad de pulso, de los parámetros de voxelización (tamaño de vóxel y valor de asignación) y de los métodos de regresión sobre los valores de las métricas ALSFW y sobre la estimación de atributos de estructura del bosque. Para ello, se redujo aleatoriamente la densidad de pulsos y se modificaron los parámetros de voxelización, obteniendo los valores de las métricas ALSFW para las diferentes combinaciones de parámetros. Estas mismas métricas ALSFW se emplearon para la estimación de atributos de la estructura del bosque mediante diferentes métodos de regresión. En segundo lugar, se integran métodos de procesado y análisis de datos ALSFW en una nueva herramienta llamada WoLFeX (Waveform Lidar for Forestry eXtraction) que incluye los procesos de recorte, corrección radiométrica relativa, voxelización y extracción de métricas a partir de los datos ALSFW, así como nuevas métricas descriptoras del sotobosque. En tercer lugar, se evalúa la influencia del ángulo de escaneo utilizado en la adquisición de datos ALS y la corrección radiométrica en la extracción de métricas ALSFW y en la estimación de atributos de combustibilidad forestal. Para ello, se extrajeron métricas ALSFW con y sin corrección radiométrica relativa y empleando diferentes ángulos de escaneo. En cuarto lugar, se caracteriza la oclusión de la señal a lo largo de la estructura vertical del bosque empleando y comparando tres tipos diferentes de láser escáner (ALSFW, ALSD y láser escáner terrestre: TLS, por sus siglas en inglés), determinando así sus limitaciones en la detección de material vegetativo en dos ecosistemas forestales diferenciados: el boreal y el mediterráneo. Para cuantificar la oclusión de la señal a lo largo de la estructura vertical del bosque se propone un nuevo parámetro, la tasa de reducción del pulso, basada en el porcentaje de haces láser bloqueados antes de alcanzar una posición dada. En quinto lugar, se evalúa la forma en que se detectan y determinan las clases de densidad de sotobosque mediante los diferentes tipos de ALS. Se compararon los perfiles de distribución vertical en los estratos inferiores descritos por el ALSFW y el ALSD con respecto a los descritos por el TLS, utilizando este último como referencia. Asimismo, se determinaron las clases de densidad de sotobosque aplicando la curva Lorenz y el índice Gini a partir de los perfiles de distribución vertical descritos por ALSFW y ALSD. Finalmente, se aplican y evalúan las nuevas métricas ALSFW basadas en la voxelización, utilizando como referencia los atributos extraídos a partir del TLS, para estimar la altura, la cobertura y el volumen del sotobosque en un ecosistema mediterráneo.
[EN] This thesis addresses the development of ALSFW processing and analysis methods to characterize the vertical forest structure, in particular, the understory vegetation. To answer this overarching goal, a total of six specific objectives were established: Firstly, the influence of pulse density, voxel parameters (i.e., voxel size and assignation value) and regression methods on ALSFW metric values and on estimates of forest structure attributes are analyzed. To do this, pulse density was randomly reduced and voxel parameters modified, obtaining ALSFW metric values for the different parameter combinations. These ALSFW metrics were used to estimate forest structure attributes with different regression methods. Secondly, a set of ALSFW data processing and analysis methods are integrated in a new software named WoLFeX (Waveform Lidar for Forestry eXtraction), including clipping, relative radiometric correction, voxelization and ALSFW metric extraction, and proposing new metrics for understory vegetation. Thirdly, the influence of the scan angle of ALS data acquisition and radiometric correction on the extraction of ALSFW metrics and on modeling forest fuel attributes is assessed. To do this, ALSFW metrics were extracted applying and without applying relative radiometric correction and using different scan angles. Fourthly, signal occlusion is characterized along the vertical forest structure using and comparing three different laser scanning configurations (ALSFW, ALSD and terrestrial laser scanning: TLS), determining their limitations in the detection of vegetative material in two contrasted forest ecosystems: boreal and Mediterranean. To quantify signal occlusion along the vertical forest structure, a new parameter based on the percentage of laser beams blocked prior to reach a given location, the rate of pulse reduction, is proposed. Fifthly, the assessment of how understory vegetation density classes are detected and determined by different ALS configurations is done. Vertical distribution profiles at the lower strata described by ALSFW and ALSD are compared with those described by TLS as reference. Moreover, understory vegetation density classes are determined by applying the Lorenz curve and Gini index from the vertical distribution profiles described by ALSFW and ALSD. Finally, the new proposed voxel-based ALSFW metrics are applied and evaluated, using TLS-based attributes as a reference, to estimate understory height, cover and volume in a Mediterranean ecosystem.
[CA] Aquesta tesi aborda el desenvolupament de mètodes de processament i anàlisi de dades ALSFW per a la caracterització de l'estructura vertical del bosc i, en particular, del sotabosc. Per a respondre a aquest objectiu general, s'establiren sis objectius específics: En primer lloc, s'analitza la influència de la densitat de pols, dels paràmetres de voxelització (grandària de vóxel i valor d'assignació) i dels mètodes de regressió sobre els valors de les mètriques ALSFW i sobre l'estimació dels atributs d'estructura del bosc. Per a això, es reduí aleatòriament la densitat de polsos i es modificaren els paràmetres de voxelització, obtenint els valors de les mètriques ALSFW per a les diferents combinacions de paràmetres. Aquestes mètriques ALSFW s'empraren per a l'estimació d'atributs de l'estructura del bosc mitjançant diferents mètodes de regressió. En segon lloc, s'integraren mètodes de processament i d'anàlisi de dades ALSFW en una nova eina anomenada WoLFeX (Waveform Lidar for Forestry eXtraction) que inclou el processos de retallada, correcció radiomètrica relativa, voxelització i extracció de mètriques a partir de les dades ALSFW, així com noves mètriques descriptores del sotabosc. En tercer lloc, s'avalua la influència de l'angle de escaneig emprat en l'adquisició de les dades ALS i la correcció radiomètrica en l'extracció de mètriques ALSFW i en l'estimació d'atributs de combustibilitat forestal. Per a això, s'extragueren mètriques ALSFW amb i sense correcció radiomètrica relativa i emprant diferents angles d'escaneig. En quart lloc, es caracteritza l'oclusió del senyal al llarg de l'estructura vertical del bosc emprant i comparant tres tipus diferents de làser escàner (ALSFW, ALSD i làser escàner terrestre: TLS, per les seues sigles en anglès), determinant així les seues limitacions en la detecció de material vegetatiu en dos ecosistemes diferenciats: un boreal i un mediterrani. Per a quantificar l'oclusió del senyal al llarg de l'estructura vertical del bosc es proposa un nou paràmetre, la taxa de reducció del pols, basada en el percentatge de rajos làser bloquejats abans d'arribar a una posició donada. En cinquè lloc, s'avalua la manera en la qual es detecten i determinen les classes de densitat de sotabosc mitjançant els diferents tipus d'ALS. Es compararen els perfils de distribució vertical en estrats inferiors descrits per l'ALSFW i l'ALSD respecte als descrits pel TLS, emprant aquest últim com a referència. A més a més, es determinaren les classes de densitat de sotabosc aplicant la corba Lorenz i l'índex Gini a partir dels perfils de distribució vertical descrits per l'ALSFW i l'ALSD. Finalment, s'apliquen i avaluen les noves mètriques ALSFW basades en la voxelització, emprant com a referència els atributs extrets a partir del TLS, per a estimar l'alçada, la cobertura i el volum del sotabosc en un ecosistema mediterrani.
Crespo Peremarch, P. (2020). Processing and analysis of airborne fullwaveform laser scanning data for the characterization of forest structure and fuel properties [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/153715
TESIS

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McCarley, Justin Craig. "Using Repeat Terrestrial Laser Scanning and Photogrammetry to Monitor Reactivation of the Silt Creek Landslide in the Western Cascade Mountains, Linn County, Oregon." Thesis, Portland State University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10748247.

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Landslides represent a serious hazard to people and property in the Pacific Northwest. Currently, the factors leading to sudden catastrophic failure vs. gradual slow creeping are not well understood. Utilizing high-resolution monitoring techniques at a sub-annual temporal scale can help researchers better understand the mechanics of mass wasting processes and possibly lead to better mitigation of their danger. This research used historical imagery analysis, precipitation data, aerial lidar analysis, Structure from Motion (SfM) photogrammetry, terrestrial laser scanning (TLS), and hydrologic measurements to monitor displacement of the Silt Creek Landslide in the western Cascade Mountain Range in Linn County, Oregon. This landslide complex is ~4 km long by ~400 m wide. The lower portion of the landslide reactivated following failure of an internal scarp in June 2014. Precipitation was measured on site and historical precipitation data was determined from a nearby SNOTEL site. Analysis of aerial lidar data found that the internal scarp failure deposited around 1.00 x 10⁶ m³ of material over an area of 1.20 x 10⁵ m² at the uppermost portion of the reactivated slide. Aerial lidar analysis also found that displacement rates on the slide surface were as high as 3 m/yr during the 2015 water year, which was the year immediately following the failure. At the beginning of the 2016 water year, very low altitude aerial images were collected and used to produce point cloud data, via SfM, of a deformed gravel road which spans a portion of the reactivated slide. The SfM data were complimentary to the aerial and TLS scans. The SfM point cloud had an average point density of > 7500 points per square meter. The resulting cloud was manipulated in 3D software to produce a model of the road prior to deformation. This was then compared to the original deformed model. Average displacement found in the deformed gravel road was 7.5 m over the 17 months between the scarp failure and the collection of the images, or ~3 m/yr. TLS point clouds were collected quarterly over the course of the 2016 water year at six locations along the eastern margin of the reactivated portion of the landslide. These 3D point cloud models of the landslide surface had an average density of 175 points per square meter. Scans were georeferenced to UTM coordinates and relative alignment of the scans was accomplished by first using the iterative closest point algorithm to align stable, off-slide terrain, and then applying the same rigid body translation to the entire scan. This was repeated for each scan at each location. Landmarks, such as tree trunks, were then manually selected at each location and their coordinates were recorded from the initial scan and each successive scan to measure displacement vectors. Average annual displacement for the 2016 water year ranged from a maximum of 0.92 m/yr in the uppermost studied area of the slide, to a low of 0.1 m/yr at the toe. Average standard deviation of the vectors of features on stable areas was 0.039 m, corresponding to a minimum detectable displacement of about ±4 cm. Displacement totals decreased with increasing distance downslope from the internal scarp failure. Additionally, displacement tended to increase with increasing distance laterally onto the slide body away from the right margin at all locations except the uppermost, where displacement rates were relatively uniform for all landmarks. Volumetric discharge measurements were collected for Silt Creek in 2016 using salt dilution gauging and found that discharge in the upslope portion of the study area wwas ~1 m3/s and increased to ~1.6 m3/s in the downslope portion. Landslide displacement rates were found to be much lower during the 2016 water year than during the 2015 water year, despite higher precipitation. This suggests that the over-all displacement trend was decoupled from precipitation values. Displacement rates at all locations on the slide decreased with each successive scan period with some portions of the landslide stopping by autumn of 2016, suggesting the study captured the slide as it returned to a state of stability. The spatial and temporal pattern of displacement is consistent with the interpretation that the landslide reactivation was a response to the undrained load applied by the internal scarp failure. This finding highlights the importance of detailed landslide monitoring to improve hazard estimation and quantification of landslide mechanics. (Abstract shortened by ProQuest.)

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Fagerström, Viktor. "Structure from Motion, a Cheaper Alternative for Three-Dimensional Modeling in Earth Science." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-352372.

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In this report, two methods for three-dimensional modeling are evaluated against each other. The first method is terrestrial laser scanning (LiDAR) that uses a laser beam to record the surrounding environment, and the second one is called Structure from Motion (SfM). The SfM technique works on the same bases as photogrammetry, which is that an object of interest is photographed from multiple angles with overlapping images and mutual points are identified and used to create a three- dimensional model. Since both the equipment and the software used to produce LiDAR models are very expensive the main thought of this project was to produce the SfM model using a cellphone camera and free open source software. The study was carried out in such a way that a “before and after” -model was generated of a small snowy mound to see how well the SfM method performed compared to the LiDAR method. The final result revealed that SfM method deviated with approximately 8mm from the LiDAR method. One of the main difficulties during this project was to correctly reference the models against exact coordinate, which also could have been one reason to why the two models differed the way they did. Taking into consideration the user-friendliness and the low cost of the SfM method, it is a very promising tool for earth science related field research.
I denna rapport så kommer två metoder för att framställa tredimensionella modeller att jämföras mot varandra. Den ena metoden är markbunden laserscanning (LiDAR), vilket använder sig av en scanner som skickar ut en laserstråle som scannar av omgivningen. Den andra metoden använder en teknik som kallas för ”Structure-from- Motion” (SfM). SfMs grunder bygger på samma teknik som används inom fotogrammetri, vilket är att objektet av intresse fotograferas, med en vanlig kamera, med ett flertal överlappande bilder och gemensamma punkter i dessa bilder används för att producera en tredimensionell modell. Då både utrustning och programvaran för att producera laserscanningar är mycket kostsamma så är grundtanken med denna undersökning att endast använda en mobiltelefonkamera och gratis öppen källkod programvara för att producera SfM modellen. Själva undersökningen gick till på så sätt att en ”före och efter” modell skapades av en snöhög med båda teknikerna för att se hur bra SfM förhöll sig mot LiDAR metoden. Resultatet visade sig att SfM metoden avvek från LiDAR-resultatet med ungefär 8mm. En av de största svårigheterna med detta projekt var att korrekt referera modellerna till exakta koordinater, vilket även kan vara en av orsakerna till att modellerna inte korrelerade med varandra helt och hållet. Med tanke på användarvänligheten och kostnaden för SfM metoden så är detta ett mycket lovande verktyg för användning inom geovetenskap.

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Klein, Danieli Regina. "Morfometria e Crescimento Diamétrico de Araucaria angustifolia (Bertol.) Kuntze no Planalto Sul Catarinense." Universidade do Estado de Santa Catarina, 2017. http://tede.udesc.br/handle/handle/2340.

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PROMOP
CAPES
Through the morphometric indices one can infer about the necessary space that the species needs to develop, maintain its growth and production rates. Allied to this, diametric growth information can portray competition in a stand, indicating the need for management practices. Objective of the proposed study to analyze the morphometry and behavior of the development and diametric increase of Araucária angustifolia through dendrochronology. In addition, data collected in the field were compared with information generated by cloud of points captured by the terrestrial Laser scanner equipment. For an analysis of the morphometry data were collected from 121 individual trees, for the purpose 127 samples and how to evaluate the information Laser 18 individuals sampled. Araucarias belong to two sites in the municipality of São José do Cerrito, in Santa Catarina. (Dc), height (h), crown height (Hc), crown radius (Rc), crown length (Cc), crown diameter (IS), the degree of slenderness (GE), the formal crown (Fc), crown ratio (Pc%), crown area (Ac) and sociological position (s) In addition to removal of increment rolls. For the morphometric relationships, 11 significant correlations were obtained and as 5 higher correlations (Dap, hic, Cc, Dc, Pc%, IA and GE) were adjusted for their determination, logarithmic E. A covariance analysis was found to exist in the morphometric relationships evaluated for each case sampled. (PS2) 0.223 m2 and dominated (PS3) 0.356 m2. For site 2, PS1 had a mean of 0.381 m2, PS2 0.360 m2 and PS3 0.300 m2. The study showed that IPAd is correlated with canopy characteristics, being a hic, Cc, Pc (%) and GE. A means of communication between variable, dendrometric and morphological means, by traditional methods of measurement and captured by Laser station, did not present significant difference between them. However, the methodologies proposed in literature are susceptible to failures, mainly, by the influence of points that do not correspond to the surface of the tree. However, the shape of the crown for each class of Dap showed that the species has different contours throughout its development stage, characterizing a conical cup in the juvenile phase, and with a maturity or shape tend to be configured in a flat way, or Then identifying a shape of umbel. For the methodologies to be comprehensive for a species, the case studies are as follows, the analyzes are welcome, the diametral amplitude is greater for the inferences, besides evaluating the viability of the images generated by the Scanning terrestrial laser scanner in the Forest mensuration
Através dos índices da morfometria pode-se inferir sobre o espaço necessário que determinada espécie necessita para se desenvolver, manter suas taxas de crescimento e produção. Aliado a isso, informações de crescimento diamétrico conseguem retratar quadro de competição em um povoamento, indicando a necessidade de práticas de manejo. O objetivo do estudo proposto foi analisar a morfometria e o comportamento do desenvolvimento e incremento diamétrico de Araucaria angustifolia através da dendrocronologia. Além disso, foram comparados dados coletados em campo com informações geradas pela nuvem de pontos captada pelo equipamento Laser scanner terrestre. Para a análise da morfometria foram coletados dados de 121 árvores individuais, para incremento foram utilizadas 127 árvores e para avaliar as informações Laser 18 indivíduos amostrados. As araucárias pertenciam a dois sítios no município de São José do Cerrito, em Santa Catarina. Foram mensuradas as variáveis: diâmetro a altura do peito (Dap), altura (h), altura de início de copa (hic), raio de copa (Rc), comprimento de copa (Cc), diâmetro de copa (Dc), índice de abrangência (IA), índice de saliência (IS), grau de esbeltez (GE), formal de copa (Fc), proporção de copa (Pc%), área de copa (Ac) e a posição sociológica (s) de cada indivíduo, além da retirada de rolos de incremento. Para as relações morfométricas obteve-se 11 correlações significativas e para as 5 maiores correlações (Dap, hic, Cc, Dc, Pc%, IA e GE) foram ajustados modelos para sua determinação, sendo caracterizados com distribuição gama e normal, e funções identidade e logarítmica. A análise de covariância demonstrou existir diferenças nas relações morfométricas avaliadas para cada sítio amostrado. Para a análise do incremento periódico anual em diâmetro (IPAd), o sítio 1, em árvores dominantes (PS1) teve média de 0,235 m2, codominantes (PS2) 0,223 m2 e dominadas (PS3) 0,356 m2. Para o sitio 2, PS1 teve média de 0,381 m2, PS2 0,360 m2 e PS3 0,300 m2. O estudo mostrou que IPAd está correlacionado com as características da copa, sendo elas, a hic, Cc, Pc(%) e o GE. A comparação entre as médias das variáveis dendrométricas e morfométricas, pelos métodos de mensuração, tradicional e captado pela estação Laser, não apresentaram diferença significativa entre si. Porém, as metodologias propostas em literatura estão suscetíveis a falhas, principalmente, pela influência de pontos que não correspondem a superfície da árvore. Já para o formato da copa para cada classe de Dap mostrou que a espécie possui diferentes contornos ao longo do seu estágio de desenvolvimento, caracterizando uma copa cônica na fase juvenil, e com a maturidade o formato tende a configurar-se de maneira plana, ou então identificando uma forma de umbela. Para que as metodologias sejam abrangentes a espécie, são necessários estudos que incluem diferentes sítios amostrais, bem como, uma amplitude diamétrica maior para gerar inferências, além de avaliar a viabilidade do uso de imagens geradas pela varredura Laser scanner terrestre na mensuração florestal

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Benaud, Pia Emma. "Exploring the multiple techniques available for developing an understanding of soil erosion in the UK." Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/32939.

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Accelerated soil erosion and the subsequent decline in soil depth has negative environmental, and consequently financial, impacts that have implications across all land cover classifications and scales of land management. Ironically, although attempts to quantify soil erosion nationally have illustrated that soil erosion can occur in the UK, understanding whether or not the UK has a soil erosion problem still remains a question to be answered. Accurately quantifying rates of soil erosion requires capturing both the volumetric nature of the visible, fluvial pathways and the subtle nature of the less-visible, diffuse pathways, across varying spatial and temporal scales. Accordingly, as we move towards a national-scale understanding of soil erosion in the UK, this thesis aims to explore some of the multiple techniques available for developing an understanding of soil erosion in the UK. The thesis first explored the information content of existing UK-based soil erosion studies, ascertaining the extent to which these existing data and methodological approaches can be used to develop an empirically derived understanding of soil erosion in the UK. The second research chapter then assessed which of two proximal sensing technologies, Terrestrial Laser Scanning and Structure-from-Motion Multi-view Stereo (SfM-MVS), is best suited to a cost-effective, replicable and robust assessment of soil erosion within a laboratory environment. The final research chapter built on these findings, using both Rare Earth Oxide tracers and SfM-MVS to elucidate retrospective information about sediment sources under changing soil erosion conditions, also within a laboratory environment Given the biased nature of the soil erosion story presented within the existing soil erosion research in the UK, it is impossible to ascertain if the frequency and magnitude of soil erosion events in the UK are problematic. However, this study has also identified that without ‘true’ observations of soil loss i.e. collection of sediment leaving known plot areas, proxies, such as the novel techniques presented in the experimental work herein and the methods used in the existing landscape scale assessments of soil erosion as included in the database chapter, are not capable of providing a complete assessment of soil erosion rates. However, this work has indicated that despite this limitation, each technique can present valuable information on the complex and spatially variable nature of soil erosion and associated processes, across different observational environments and scales.

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Tilly, Nora Isabelle Verfasser], Georg [Akademischer Betreuer] [Bareth, and Olaf [Akademischer Betreuer] Bubenzer. "Terrestrial laser scanning for crop monitoring. Capturing 3D data of plant height for estimating biomass at field scale / Nora Isabelle Tilly. Gutachter: Georg Bareth ; Olaf Bubenzer." Köln : Universitäts- und Stadtbibliothek Köln, 2016. http://d-nb.info/1091549729/34.

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Ge, Xuming [Verfasser], Thomas [Akademischer Betreuer] [Gutachter] Wunderlich, Hans-Berndt [Gutachter] Neuner, and Andreas [Gutachter] Wieser. "Terrestrial Laser Scanning Technology from Calibration to Registration with Respect to Deformation Monitoring / Xuming Ge ; Gutachter: Hans-Berndt Neuner, Andreas Wieser, Thomas Wunderlich ; Betreuer: Thomas Wunderlich." München : Universitätsbibliothek der TU München, 2016. http://d-nb.info/1120013909/34.

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Stránská, Petra. "Kombinace laserových a snímkových dat z mobilního mapovacího systému." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2021. http://www.nusl.cz/ntk/nusl-444257.

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The diploma thesis describes the data integration of data from different 3D technologies, specifically data of close range photogrammetry, aerial photogrammetry using RPAS and terrestrial laser scanning. The thesis deals mainly with fotogrammetric processing in ContextCapture software and data integration in this software. The thesis also describes a construction of a calibration field. The points of the field were used as ground control points and check points during processing. The accuracy of the outputs was evaluated by statistical testing of the coordinate deviations of the control points. The result of the thesis is 3D model of one of the buildings located in the AdMaS research center.

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G, Mastrorocco. "Use of innovative technologies for the analysis of brittle failure mechanisms applied to underground and open pit marble mines." Doctoral thesis, Università di Siena, 2018. http://hdl.handle.net/11365/1039639.

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Abstract:

The exploitation of rock material usually results in a change of the in-situ force field surrounding the rock mass. Mine design is one of the major challenges when planning and operating a mine in a complex environmental context such as the Apuan Alps marble district (Italy). There could be significant risks related to the safety of both personnel and equipment. This research focuses on data collection, geo-structural interpretation and rock mechanics analysis by means of advanced remote sensing techniques (e.g. Structure for Motion methods, Terrestrial Laser Scanning, change detection analysis, etc.), numerical modelling for the stability analysis of both surface and underground structures, and modelling of brittle failure. In particular, this research investigates the application of Remotely Piloted Aircraft Systems (RPASs) and of Structure from Motion (SfM) methods for geo-hazard identification, awareness and risk reduction. Limit equilibrium and numerical analyses were carried out to study the stability of two large marble blocks in an open pit marble mine area. These analyses were focused on the important role that rock bridges have on slope stability, and to investigate the active-passive wedge mechanism that may develop due to rock mass strength degradation and brittle failure mechanisms. Additionally, the spalling failure of an underground marble pillar was investigated to include a multifaceted/multitemporal stability analysis with the objective of studying mining engineering issues related with the extraction of valuable rock resources. Morphological variations were identified using a change detection approach and analysed using both Finite Element (FEM) and hybrid Finite-Discrete Element (FDEM) methods. In this context, understanding the mechanical behaviour of a rock mass has always been a major concern for increasing the safety and minimizing economic loss. A mine design concerns the stability of the excavations, including the potential collapse of slopes and quarry faces, spalling of the sidewalls, and the structurally controlled failure of the underground openings. The cornerstone of an engineering understanding of a rock mass structure is represented by data collection and interpretation. The starting point is represented by the knowledge of the lithologies and the major structural features present in the rock mass. Such information provides essential background to rock mechanics studies, but may be available in limited form using classical mapping techniques due to the limited accessibility of rock outcrops. Indeed, measurements can be made on natural slopes or on faces exposed by surface excavations, but the data collected may not be representative of the whole site. In this context, it is now possible to drastically increase the quantity of mapping information by using advanced and modern geomatics techniques. In order to analyse rock outcrops, the use of RPAS allows to overcome data acquisition issues related to high steep quarry walls, while at the same time it provides high resolution images and 3D models. This is particularly important because fractures characteristics may be spatially variable due to stress relaxation induced by excavation activity. Terrestrial Laser Scanning allows to rapidly acquire information as point clouds with a millimetre level of detail from the surrounding surfaces. Both aerial and terrestrial measurement techniques can be useful to perform detailed and accurate structural analysis and periodical estimates of surface changes by means of the so-called change detection analysis, in order to identify modified surfaces in the mining area. In this context, geomatics techniques and conventional geological/engineering-geological surveys techniques should be used simultaneously because when used together they allow to reduce data uncertainty and to provide a better characterisation of data variability. Indeed, the reliability of the analysis depends on the quality, quantity and interpretation of available field information. Many design structures in mine engineering practice involve complex problems and it is often necessary to carry out detailed rock mechanics analysis using powerful numerical tools. Indeed, stress and stability analysis can be carried out using continuous and/or discontinuous numerical approaches. These techniques are currently used in the civil and mining engineering sectors due to the possibility to take account of complex rock mass deformation and failure. Numerical methods allow to consider the whole rock mass mechanical behaviour on the contrary of classical approaches that, for example, consider a block as an isolated object. In this context, numerical methods are able to investigate and illustrate the involved rock failure mechanisms during mining activities and particularly the initiation, propagation, and coalescence of cracks, and the propagation of discrete fractures.

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50

Schneider, Danilo. "Geometrische und stochastische Modelle für die integrierte Auswertung terrestrischer Laserscannerdaten und photogrammetrischer Bilddaten." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-24093.

Full text

Abstract:

Terrestrische Laserscanner finden seit einigen Jahren immer stärkere Anwendung in der Praxis und ersetzen bzw. ergänzen bisherige Messverfahren, oder es werden neue Anwendungsgebiete erschlossen. Werden die Daten eines terrestrischen Laserscanners mit photogrammetrischen Bilddaten kombiniert, ergeben sich viel versprechende Möglichkeiten, weil die Eigenschaften beider Datentypen als weitestgehend komplementär angesehen werden können: Terrestrische Laserscanner erzeugen schnell und zuverlässig dreidimensionale Repräsentationen von Objektoberflächen von einem einzigen Aufnahmestandpunkt aus, während sich zweidimensionale photogrammetrische Bilddaten durch eine sehr gute visuelle Qualität mit hohem Interpretationsgehalt und hoher lateraler Genauigkeit auszeichnen. Infolgedessen existieren bereits zahlreiche Ansätze, sowohl software- als auch hardwareseitig, in denen diese Kombination realisiert wird. Allerdings haben die Bildinformationen bisher meist nur ergänzenden Charakter, beispielsweise bei der Kolorierung von Punktwolken oder der Texturierung von aus Laserscannerdaten erzeugten Oberflächenmodellen. Die konsequente Nutzung der komplementären Eigenschaften beider Sensortypen bietet jedoch ein weitaus größeres Potenzial. Aus diesem Grund wurde im Rahmen dieser Arbeit eine Berechnungsmethode – die integrierte Bündelblockausgleichung – entwickelt, bei dem die aus terrestrischen Laserscannerdaten und photogrammetrischen Bilddaten abgeleiteten Beobachtungen diskreter Objektpunkte gleichberechtigt Verwendung finden können. Diese Vorgehensweise hat mehrere Vorteile: durch die Nutzung der individuellen Eigenschaften beider Datentypen unterstützen sie sich gegenseitig bei der Bestimmung von 3D-Objektkoordinaten, wodurch eine höhere Genauigkeit erreicht werden kann. Alle am Ausgleichungsprozess beteiligten Daten werden optimal zueinander referenziert und die verwendeten Aufnahmegeräte können simultan kalibriert werden. Wegen des (sphärischen) Gesichtsfeldes der meisten terrestrischen Laserscanner von 360° in horizontaler und bis zu 180° in vertikaler Richtung bietet sich die Kombination mit Rotationszeilen-Panoramakameras oder Kameras mit Fisheye-Objektiv an, weil diese im Vergleich zu zentralperspektiven Kameras deutlich größere Winkelbereiche in einer Aufnahme abbilden können. Grundlage für die gemeinsame Auswertung terrestrischer Laserscanner- und photogrammetrischer Bilddaten ist die strenge geometrische Modellierung der Aufnahmegeräte. Deshalb wurde für terrestrische Laserscanner und verschiedene Kameratypen ein geometrisches Modell, bestehend aus einem Grundmodell und Zusatzparametern zur Kompensation von Restsystematiken, entwickelt und verifiziert. Insbesondere bei der Entwicklung des geometrischen Modells für Laserscanner wurden verschiedene in der Literatur beschriebene Ansätze berücksichtigt. Dabei wurde auch auf von Theodoliten und Tachymetern bekannte Korrekturmodelle zurückgegriffen. Besondere Bedeutung innerhalb der gemeinsamen Auswertung hat die Festlegung des stochastischen Modells. Weil verschiedene Typen von Beobachtungen mit unterschiedlichen zugrunde liegenden geometrischen Modellen und unterschiedlichen stochastischen Eigenschaften gemeinsam ausgeglichen werden, muss den Daten ein entsprechendes Gewicht zugeordnet werden. Bei ungünstiger Gewichtung der Beobachtungen können die Ausgleichungsergebnisse negativ beeinflusst werden. Deshalb wurde die integrierte Bündelblockausgleichung um das Verfahren der Varianzkomponentenschätzung erweitert, mit dem optimale Beobachtungsgewichte automatisch bestimmt werden können. Erst dadurch wird es möglich, das Potenzial der Kombination terrestrischer Laserscanner- und photogrammetrischer Bilddaten vollständig auszuschöpfen. Zur Berechnung der integrierten Bündelblockausgleichung wurde eine Software entwickelt, mit der vielfältige Varianten der algorithmischen Kombination der Datentypen realisiert werden können. Es wurden zahlreiche Laserscannerdaten, Panoramabilddaten, Fisheye-Bilddaten und zentralperspektive Bilddaten in mehreren Testumgebungen aufgenommen und unter Anwendung der entwickelten Software prozessiert. Dabei wurden verschiedene Berechnungsvarianten detailliert analysiert und damit die Vorteile und Einschränkungen der vorgestellten Methode demonstriert. Ein Anwendungsbeispiel aus dem Bereich der Geologie veranschaulicht das Potenzial des Algorithmus in der Praxis
The use of terrestrial laser scanning has grown in popularity in recent years, and replaces and complements previous measuring methods, as well as opening new fields of application. If data from terrestrial laser scanners are combined with photogrammetric image data, this yields promising possibilities, as the properties of both types of data can be considered mainly complementary: terrestrial laser scanners produce fast and reliable three-dimensional representations of object surfaces from only one position, while two-dimensional photogrammetric image data are characterised by a high visual quality, ease of interpretation, and high lateral accuracy. Consequently there are numerous approaches existing, both hardware- and software-based, where this combination is realised. However, in most approaches, the image data are only used to add additional characteristics, such as colouring point clouds or texturing object surfaces generated from laser scanner data. A thorough exploitation of the complementary characteristics of both types of sensors provides much more potential. For this reason a calculation method – the integrated bundle adjustment – was developed within this thesis, where the observations of discrete object points derived from terrestrial laser scanner data and photogrammetric image data are utilised equally. This approach has several advantages: using the individual characteristics of both types of data they mutually strengthen each other in terms of 3D object coordinate determination, so that a higher accuracy can be achieved; all involved data sets are optimally co-registered; and each instrument is simultaneously calibrated. Due to the (spherical) field of view of most terrestrial laser scanners of 360° in the horizontal direction and up to 180° in the vertical direction, the integration with rotating line panoramic cameras or cameras with fisheye lenses is very appropriate, as they have a wider field of view compared to central perspective cameras. The basis for the combined processing of terrestrial laser scanner and photogrammetric image data is the strict geometric modelling of the recording instruments. Therefore geometric models, consisting of a basic model and additional parameters for the compensation of systematic errors, was developed and verified for terrestrial laser scanners and different types of cameras. Regarding the geometric laser scanner model, different approaches described in the literature were considered, as well as applying correction models known from theodolites and total stations. A particular consideration within the combined processing is the definition of the stochastic model. Since different types of observations with different underlying geometric models and different stochastic properties have to be adjusted simultaneously, adequate weights have to be assigned to the measurements. An unfavourable weighting can have a negative influence on the adjustment results. Therefore a variance component estimation procedure was implemented in the integrated bundle adjustment, which allows for an automatic determination of optimal observation weights. Hence, it becomes possible to exploit the potential of the combination of terrestrial laser scanner and photogrammetric image data completely. For the calculation of the integrated bundle adjustment, software was developed allowing various algorithmic configurations of the different data types to be applied. Numerous laser scanner, panoramic image, fisheye image and central perspective image data were recorded in different test fields and processed using the developed software. Several calculation alternatives were analysed, demonstrating the advantages and limitations of the presented method. An application example from the field of geology illustrates the potential of the algorithm in practice

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