To see the other types of publications on this topic, follow the link: DEM-LIDAR.
Dissertations / Theses on the topic 'DEM-LIDAR'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 35 dissertations / theses for your research on the topic 'DEM-LIDAR.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Rangelova, Sandra. "Methods for assessing the consistency of the New National Height Model." Thesis, KTH, Fastigheter och byggande, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-299788.
Full textAbstract:
Digital Elevation Models (DEM) are a simple representation of the Earth’s surface. DEMs play an important role in the field of remote sensing and GIS and are used as basis for mapping and analysis for a vest majority of scientific applications. There are many ways of producing DEMs, however the direct geo-referencing technology has made Airborne Laser Scanning (ALS) a preferred technology for the acquisition of accurate surface models over broad areas. ALS uses LiDAR (Light Detection and Ranging) which uses light in a form of pulsed laser to measure distances. Before the introduction of the DEM called Ny Nationell Höjdmodell (NNH), the highest level of height data over Sweden was the GSD-altitude data (Geographical Sweden Data). The NNH was a project by Lantmäteriet, where between 2009-2019 the entire Sweden was laser scanned. The product was a new height model called Laser Data NH with positional accuracy of 0,1 m in height and relative accuracy of 0,15 m. This project focuses on testing few methods for consistency assessment between the overlapping strips using linear features. Linear features are extracted for each overlapping area, based on intersection between planar patches extracted from gable rooftops. The first method of this study computes the distance between the overlapping areas without linear features, using two approaches: cloud-to-cloud distance and mesh-to-cloud distance. The second method computes the transformation shifts and rotations needed for the linear features to align by registering the strips with both levelled and not levelled registration. In the third method, distances and angles are measured between the lines, to further analyze how well the strips fit together. The distances are measured as distance between a mid-point of one line in the first LiDAR strip and the line on the second LiDAR strip, for all linear features. The distances were measures both as 3D distances and separately as horizontal and vertical distances. As a final step a hypothesis testing was performed to determine whether the distances and angles between the lines are significant or whether any systematic error is present in the point cloud. Based on the results obtained from the first method, significant distance between the point clouds was obtained. The results from the mesh-to-cloud distance yielded better result with higher uncertainty. According to the second method significant distances between the linear features were obtained based on the registration. The mean absolute error of the registrations showed an error at a dm level, with a minimal rotation in the vertical plane for the coalignment for the levelled registration. The third method showed a mean distance between the linear features of 20 cm. Moreover, this method showed a significant inconsistence between the linear features in the vertical plane based on the high standard uncertainty.Digitala höjdmodeller (DEM) är en enkel representation av jordens yta. DEM spelar en viktig roll inom fjärranalys och GIS och används som grund för kartläggning och analys för en majoritet av vetenskapliga tillämpningar. Det finns många sätt att producera DEM, men den direkta georefereringstekniken har gjort Airborne Laser Scanning (ALS) till en föredragen teknik för förvärv av exakta ytmodeller över breda områden. ALS använder LiDAR (Light Detection and Ranging) som använder ljus i form av pulserande laser för att mäta avstånd. Före introduktionen av Ny Nationell Höjdmodell (NNH) var den högsta nivån av höjddata över Sverige GSD-höjddata (Geographical Sweden Data). NNH var ett projekt av Lantmäteriet, där mellan 2009-2019 laserscannades hela Sverige. Produkten var en ny höjdmodell som heter Laserdata NH med positionsnoggrannhet på 0,1 m i höjd och relativ noggrannhet på 0,15 m. Detta projekt fokuserar på att testa få metoder för konsekvensbedömning mellan de överlappande remsorna med hjälp av linjära funktioner. Linjära funktioner extraheras för varje överlappande område, baserat på skärningspunkten mellan plana fläckar extraherade från gaveltak. Den första metoden för denna studie beräknar avståndet mellan de överlappande områdena utan linjära funktioner, med två metoder: moln-till-moln-avstånd och nät-till-moln-avstånd. Den andra metoden beräknar de transformationsförskjutningar och rotationer som behövs för att de linjära särdragen ska kola genom att registrera remsorna med både nivellerad och inte nivellerad registrering. I den tredje metoden mäts avstånd och vinklar mellan linjerna, för att ytterligare analysera hur bra remsorna passar ihop. Avstånden mäts som avstånd mellan en mittpunkt på en linje i den första LiDAR-remsan och linjen på den andra LiDAR-remsan, för alla linjära funktioner. Avstånden var mått både som 3D -avstånd och separat som horisontella och vertikala avstånd. Som ett sista steg utfördes en hypotesprovning för att avgöra om avstånden och vinklarna mellan linjerna är signifikanta eller om det finns något systematiskt fel i punktmolnet. Baserat på resultaten från den första metoden erhölls ett betydande avstånd mellan punktmolnen. Resultaten från mask-till-moln-avståndet gav bättre resultat med högre osäkerhet. Enligt den andra metoden erhölls betydande avstånd mellan de linjära särdragen baserat på registreringen. Det genomsnittliga absoluta felet för registreringarna visade ett fel på en dm -nivå, med en minimal rotation i det vertikala planet för samlinjering för den jämnade registreringen. Den tredje metoden visade ett medelavstånd mellan de linjära särdragen på 20 cm. Dessutom visade denna metod en signifikant inkonsekvens mellan de linjära särdragen i det vertikala planet baserat på hög standardosäkerhet.
2
Gadre, Mandar M. "Automated building footprint extraction from high resolution LIDAR DEM imagery." Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/4320.
Full textAbstract:
Thesis (M.S.)--University of Missouri-Columbia, 2005.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (July 13, 2006) Includes bibliographical references.
3
Gagné, Marissa Marlene. "An Analysis and Critique of DEM Creaion and 3-D Modeling Using Airborne LIDAR and Photogrammetric Techniques." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/43528.
Full textAbstract:
Three-dimensional (3D) visualization is rapidly becoming an important tool for many engineering projects. Accurate digital representations of terrain and ground features are extremely useful for efficient design, communication and data representation in projects involving land development, transportation planning, hydrologic analysis, environmental impact studies, and much more. Within the scope of terrain modeling lie a wide variety of techniques used to build digital elevation models (DEMs). Each approach has inherent problems and difficulties that can alter the accuracy and usability of the DEM produced.
The main objectives of this study are to examine the various methods used for the creation of digital elevation models and make recommendations as to the appropriate techniques to use depending on specific project circumstances. Data sets generated using two of the methods, photogrammetry and LIDAR, are used to build digital terrain models in various software packages for an analysis of data usability and function.
The key results of this research project are two DEMs of a real-world transportation study area and a set of conclusions and recommendations that give insight into the exact methods to be used on various projects. The paper ends with two short appendices, the first of which discusses several software packages and their effectiveness in DEM creation and 3-D modeling. The final appendix is a flow chart summarizing the recommendations for the seven DEM creation methods.Master of Science
4
Popescu, Sorin Cristian. "Estimating Plot-Level Forest Biophysical Parameters Using Small-Footprint Airborne Lidar Measurements." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/27109.
Full textAbstract:
The main study objective was to develop robust processing and analysis techniques to facilitate the use of small-footprint lidar data for estimating forest biophysical parameters measuring individual trees identifiable on the three-dimensional lidar surface. This study derived the digital terrain model from lidar data using an iterative slope-based algorithm and developed processing methods for directly measuring tree height, crown diameter, and stand density. The lidar system used for this study recorded up to four returns per pulse, with an average footprint of 0.65 m and an average distance between laser shots of 0.7 m. The lidar data set was acquired over deciduous, coniferous, and mixed stands of varying age classes and settings typical of the southeastern United States (37° 25' N, 78° 41' W). Lidar processing techniques for identifying and measuring individual trees included data fusion with multispectral optical data and local filtering with both square and circular windows of variable size. The window size was based on canopy height and forest type. The crown diameter was calculated as the average of two values measured along two perpendicular directions from the location of each tree top, by fitting a four-degree polynomial on both profiles. The ground-truth plot design followed the U.S. National Forest Inventory and Analysis (FIA) field data layout. The lidar-derived tree measurements were used with regression models and cross-validation to estimate plot level field inventory data, including volume, basal area, and biomass. FIA subplots of 0.017 ha each were pooled together in two categories, deciduous trees and pines. For the pine plots, lidar measurements explained 97% of the variance associated with the mean height of dominant trees. For deciduous plots, regression models explained 79% of the mean height variance for dominant trees. Results for estimating crown diameter were similar for both pines and deciduous trees, with R2 values of 0.62-0.63 for the dominant trees. R2 values for estimating biomass were 0.82 for pines (RMSE 29 Mg/ha) and 0.32 for deciduous (RMSE 44 Mg/ha). Overall, plot level tree height and crown diameter calculated from individual tree lidar measurements were particularly important in contributing to model fit and prediction of forest volume and biomass.Ph. D.
5
Fava, Marica. "LIDAR Aviotrasportati Mediante RPAS." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2016.
Find full textAbstract:
Tesi riguardante i LIDAR aviotrasportati mediante RPAS, cioè relativa alla realizzazione di rilievi LIDAR utilizzando come mezzo di trasporto dei sensori (Laser scanner, Piattaforma inerziale, ricevitore GPS) i droni. Nella trattazione, sono state affrontate le principali caratteristiche tecnologiche e funzionali dei vari strumenti impiegati nel rilievo LIDAR, cercando di comprenderne il ruolo individuale e la relativa sinergia.
6
Bogren, Fredrik. "LIDAR-analys av flygsanddyner i Västerbottens inland : Har dynmorfologi bildad under tidigare interstadialer bevarats i landskapet?" Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-104812.
Full textAbstract:
The aim of this study was to map the prevalence of aeolian sand dunes in Västerbotten, northern Sweden to find dunes formed during earlier deglaciation phases, which was then preserved in cold-based conditions during the youngest stadial of the Weichselian glaciation. These preserved dunes were expected to be covered by a layer of till and have a rather faint morphology compared to dunes formed during the Holocene. Consequently, high resolution LIDAR-derived images from the Swedish mapping, cadastral and land registration authority (Lantmäteriet) was used to detect the dunes throughout an area covering most of Västerbotten, above the highest coastline and below the mountain range. The analysis resulted in several new findings of aeolian dunes compared to the findings in the quaternary soil map created by the Geological Survey of Sweden. Despite the fact some of the dunes at the LIDAR-derived image had a strange faint appearance, it was quickly evident during the fieldwork that the aeolian sand was not covered by till on any of the dunes visited. The common view during the last decades has been that cold-based ice will not erode or alter the morphology of the landscape beneath the ice. However, this study suggests that hypothesis may not be entirely correct, and therefore it can be hard to use geomorphological implications to reconstruct past glacial environments. Thus, it can be concluded that even under cold-based conditions, preservation of aeolian sand dunes in Västerbotten is probably not very common.
7
Crosby, David Alexander. "The Effect of DEM Resolution on the Computation of Hydrologically Significant Topographic Attributes." Scholar Commons, 2006. http://scholarcommons.usf.edu/etd/3859.
Full textAbstract:
Terrain attributes computed from Digital Elevation Models (DEMs) are widely used in hydrology and hydrologic modeling. It is important to consider that the values of the attributes can be different depending on the resolution of the DEM from which they are derived. The question arises as to how much exactly the high-resolution DEMs created through LIDAR remote sensing techniques change the values of the terrain attributes when compared to lower resolution DEMs.In this thesis a LIDAR-derived DEM of 20 feet resolution was resampled using a nearest-neighbour algorithm to various coarser resolutions to examine and quantify the effect of DEM resolution upon a series of hydrologically significant terrain attributes including slope, surface curvature, topographic wetness index, stream power index and stream networks. Values for slope and surface curvature are found to be smaller when computed from lower resolution DEMs; values for the topographic wetness index and stream power index are found to increase as DEM cell size increases.The derived stream networks for each resolution were compared in terms of length per stream order, drainage density, bifurcation ratio, and overall accuracy indicating a loss of small detail, but only a modest change in the overall stream network morphometry. This research suggests that it is possible to establish relationships that quantify the effects of DEM resolution upon hydrologically significant terrain attributes, which can then be considered when processing DEMs from various resolutions for the purpose of parameterizing hydrologic models.
8
Bhadra, Sourav. "Assessing the Impacts of Anthropogenic Drainage Structures on Hydrologic Connectivity Using High-Resolution Digital Elevation Models." OpenSIUC, 2019. https://opensiuc.lib.siu.edu/theses/2573.
Full textAbstract:
Stream flowline delineation from high-resolution digital elevation models (HRDEMs) can be problematic due to the fine representation of terrain features as well as anthropogenic drainage structures (e.g., bridges, culverts) within the grid surface. The anthropogenic drainage structures (ADS) may create digital dams while delineating stream flowlines from HRDEMs. The study assessed the effects of ADS locations, spatial resolution (ranged from 1m to 10m), depression processing methods, and flow direction algorithms (D8, D-Infinity, and MFD-md) on hydrologic connectivity through digital dams using HRDEMs in Nebraska. The assessment was conducted based on the offset distances between modeled stream flowlines and original ADS locations using kernel density estimation (KDE) and calculated frequency of ADS samples within offset distances. Three major depression processing techniques (i.e., depression filling, stream breaching, and stream burning) were considered for this study. Finally, an automated method, constrained burning was proposed for HRDEMs which utilizes ancillary datasets to create underneath stream crossings at possible ADS locations and perform DEM reconditioning. The results suggest that coarser resolution DEMs with depression filling and breaching can produce better hydrologic connectivity through ADS compared with finer resolution DEMs with different flow direction algorithms. It was also found that stream burning with known stream crossings at ADS locations outperformed depression filling and breaching techniques for HRDEMs in terms of hydrologic connectivity. The flow direction algorithms combining with depression filling and breaching techniques do not have significant effects on the hydrologic connectivity of modeled stream flowlines. However, for stream burning methods, D8 was found as the best performing flow direction algorithm in HRDEMs with statistical significance. The stream flowlines delineated using the proposed constrained burning method from the HRDEM was found better than depression filling and breaching techniques. This method has an overall accuracy of 78.82% in detecting possible ADS locations within the study area.
9
Kniess, Ulrich. "Quantification de l’évolution de glissements de terrain argileux par des techniques de télédétection. Application à la région du Trièves (Alpes Françaises)." Thesis, Grenoble, 2011. http://www.theses.fr/2011GRENU038/document.
Full textAbstract:
Trois méthodes de télédétection (Lidar, interférométrie radar satellitaire et photogrammétrie aérienne) ont été appliquées pour quantifier les évolutions spatiales et temporelles de deux glissements argileux (Harmalière et Avignonet, situés dans la région du Trièves, Alpes françaises) en complément d’instrumentation in-situ. Une analyse géomorphologique a été réalisée à partir d’ortho-photos (depuis 1948) et du MNT Lidar filtré. Couplée à des reconnaissances géophysiques, elle a montré que la cinématique différente des deux glissements contigus était partiellement contrôlée par la paléotopographie sur laquelle s’est déposée la couche d’argile. La rugosité directionnelle a permis de distinguer les processus d’érosion résultant de mouvements gravitaires et de ravinement. Une technique de corrélation d'images adaptée aux MNT a été développée pour obtenir les vecteurs de déplacement 3D entre deux acquisitions Lidar (2006 - 2009), avec une attention particulière portée à l’évaluation de la qualité des mesures. La carte des déplacements obtenue montre que la zone la plus active du glissement de Harmalière entre 1981 et 2001 est maintenant relativement lente (déplacement <0.4 m en 3 ans), contrairement à d’autres zones proches montrant des mouvements importants atteignant 3m avec une composante rotationnelle. Pour le glissement d’Avignonet, les déplacements déduits augmentent généralement vers le pied du glissement et peuvent atteindre 1 m. La technique des réflecteurs permanents en interférométrie radar a permis de déterminer de nouvelles valeurs de taux de déplacements (entre 1992 et 2000) en 16 points du glissement, qui sont cohérentes avec les données GPS existantes. Le taux moyen de recul à long terme de l’escarpement principal a été estimé à 1-5 cm/an à Avignonet et entre 7 et 14 cm/an à l'Harmalière. La régression du glissement d’Avignonet semble contrôlée par l’érosion du sommet de la couche d’alluvions compactes reposant sur le substratum. La présence d’une paleovallée du Drac sous le pied du glissement de l'Harmalière pourrait expliquer cette différence de cinématique entre les deux glissementsThree remote sensing techniques, Lidar, satellite radar interferometry and aerial photogrammetry are applied to quantify the spatial and temporal evolution of two clayey landslides (Avignonet and Harmalière, located in the Trièves area, French Alps) in complement to in-situ instrumentations. A geomorphological analysis based on Lidar-derived filtered DEM, coupled to analysis of ortho-photos dating back to 1948 and geophysical investigations, shows that the different evolution of the neighbouring landslides could be partly controlled by the paleotopography of the bedrock underlying the clay layer. Directional roughness is shown to help distinguishing between landsliding and gully erosion patterns. Cross-correlation technique adapted to DEMs has been developed to derive 3D-displacement-vectors between two Lidar acquisitions (2006 and 2009), paying attention on measure quality assessment. The displacement map reveals that, at the Harmalière landslide, the main sliding channel, very active from 1981 - 2001, is now relatively slow (< 0.4 m over 3 years), in contrast with four surrounding distinct areas of large movements (up to 3 m) partly with rotational components. At the Avignonet landslide, displacements generally increase towards the toe (up to 1 m near the drainage outlets). Persistent Scatterers Interferometry technique allows to derive new reliable displacement-rates (1992 - 2000) at 16 points of the Avignonet landslide, consistent with GPS time-series. The long-term average headscarp retreat rates are estimated to 1 - 5 cm/y at Avignonet and 7 - 14cm/y at Harmalière. The retreat of the Avignonet landslide seems to be controlled by the erosion of the top of the underlying compacted alluvial layers. The presence of a paleovalley (Drac river) below the Harmalière toe could explain the difference of kinematics between the two landslides
10
Mora, Omar Ernesto. "Morphology-Based Identification of Surface Features to Support Landslide Hazard Detection Using Airborne LiDAR Data." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429861576.
Full text
11
Cash, Jason M. "Using Light Detection and Ranging (LiDAR) Imagery to Model Radio Wave Propagation." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/31615.
Full textAbstract:
The purpose of this study was to determine if light detection and ranging (LiDAR) imagery could provide a significantly more accurate data set for modeling near line-of-sight (LOS) propagation at higher frequencies, specifically 27.810 GHz. than a USGS digital elevation model (DEM). In addition, the study tested for significant differences in LiDAR elevation data created at various resolutions ranging from 1 to 100 meters. Finally, this study examined the effects of various classification thresholds for transforming continuous signal strength measurements into LOS or non-LOS (NLOS) classifications used in determining prediction accuracy. The capability to transmit information via higher frequency wireless equipment requires a near LOS path between the transmitter and the antenna receiving the signal. USGS DEMs, commonly used in GIS programs to predict communication viewsheds (commsheds), represent the bare earth topography and do not reflect surface features such as vegetation and buildings. In actuality these surface features can significantly influence near LOS paths and therefore a data set that contains these features can greatly improve the ability to predict commshed areas. LiDAR is a form of active imagery that records both the bare-earth as well as these surface features, at a high resolution, making it well suited for wireless modeling applications. Results indicate that signal strength threshold classification has a direct influence on the accuracy of predicted commsheds across all resolutions. Secondly, LiDAR resolutions lower than 40m as well as bare-earth DEMs were unsuccessful in predicting an accurate commshed while LiDAR resolutions coarser than 15m provided significant predictions of equal accuracy. These results indicate that high resolution LiDAR is needed to accurately model commsheds but signal strength threshold classification determines which of these higher resolutions are significant.Master of Science
12
Deshpande, Sagar Shriram. "Semi-automated Methods to Create a Hydro-flattened DEM using Single Photon and Linear Mode LiDAR Points." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1491300120665946.
Full text
13
Akyay, Tolga. "Wavelet-based Outlier Detection And Denoising Of Airborne Laser Scanning Data." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12610164/index.pdf.
Full textAbstract:
The method of airborne laser scanning &ndashalso named as LIDAR &ndash
has recently turned out to be an efficient way for generating high quality digital surface and elevation models. In this work, wavelet-based outlier detection and different wavelet thresholding (wavelet shrinkage) methods for denoising of airborne laser scanning data are discussed. The task is to investigate the effect of wavelet-based outlier detection and find out which wavelet thresholding methods provide best denoising results for post-processing. Data and results are analyzed and visualized by using a MATLAB program which was developed during this work.
14
Grumer, Magnus. "Metoder för kartering av bäckar och diken med användning av Nationella höjdmodellen och hydrologisk modellering : En undersökning av olika interpolationsmetoder och upplösningar av digitala höjdmodeller för generering av mindre vattendrag." Thesis, Karlstads universitet, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-68507.
Full textAbstract:
I detta examensarbete har det undersökts om digitala höjdmodeller, framställda från LIDAR-data som insamlats av Lantmäteriet, kan användas för komplettera och lokalisera nya bäckar och diken som inte finns med i Lantmäteriets databaser idag. I Lantmäteriets verksamhet karteras bäckar och diken först och främst idag med hjälp flygfotografier i stereo. Då metoden fungerar bra på öppen mark kan det vara svårt att urskilja bäckar under tät vegetation som till exempel barrskog. Metoden som använts för att lokalisera bäckar och diken går ut på att beräkna flödesriktningar och flödesackumuleringar i höjdmodellerna. I projektet testas hur metoden påverkas av höjdmodeller av olika upplösningar och ursprung. Förutom Lantmäteriets egna höjdmodeller testas en modell som tagit fram genom en så kallad B-spline interpolation av laserdata. Detta för att undersöka om Lantmäteriets modeller duger för att göra de hydrologiska beräkningar som krävs för att identifiera bäckar och diken. För att evaluera noggrannheten på bäckarna mäts ett antal bäckar och diken in under olika terräng- och vegetationstyper mot vilka en areaavvikelse per meter referensbäck och andelen som ligger under godkänt noggrannhetskrav i plan beräknas. Studien har visat att Lantmäteriets bäcklinjer under tät vegetation, främst barrskog, har en lägre noggrannhet än på öppen mark. Lantmäteriets egna höjdmodeller med 1 meters upplösning har visat sig prestera bäst eller likvärdigt med övriga modeller under dessa förhållanden och genererar bäckar med större noggrannhet än reda karterade bäcklinjer. Dock är metoden beroende av kompletterande information om bäckarnas utformning från till exempel flygfotografier eller fältstudier, eftersom genererade bäckar måste väljas ut manuellt. Detta gör att inga nya bäckar med absolut säkerhet kan lokaliseras med denna metod. Det rekommenderas därför att metoden endast används för att komplettera redan karterade bäckar och diken.This Master thesis investigated whether digital elevation models, derived from LiDAR data collected by the Swedish mapping and surveying agency, Lantmäteriet, which is a public authority that manages geographic information in Sweden, can be used to map streams and dikes not included in their databases today. Today Lantmäteriet identifies streams and dikes mainly with the photogrammetric methods. The methods works well on open land, but it can be difficult to distinguish smaller streams and ditches covered by dense vegetation. The method used to locate streams and dikes is to calculate flow directions and flow accumulations in the height models. The project tests how the methods are influenced by elevation models with different resolutions and origins. In addition to the national elevation model, a new model interpolated from LiDAR-data was tested, using a so-called B-spline method. This was to find out if the model produced by Lantmäteriet is useful to make the hydrological calculations required to identify streams and dikes. In order to evaluate the accuracy of the streams, a number of reference stretches of streams and dikes were surveyed in areas with different terrain and vegetation types. The area deviation per meter reference stretch and the proportion below approved accuracy was calculated. The results shows that Lantmäteriet’s mapped watercourses under dense vegetation, mainly coniferous forest, have a lower accuracy than on open fields. Lantmäteriet’s height models with 1 meter resolution have been shown to perform best or equivalent to other models under these conditions, and generate broads with greater accuracy than finding marked pelvic lines. However, the method is dependent on supplementary information about the streams distribution from, for example, aerial photographs or field studies, as generated streams must be manually selected. This means that watercourses cannot be mapped accurately with this method. It is therefore recommended that the method should only be used for supplement already mapped streams and dikes.
15
Santos, Andr? Luis Silva dos. "Monitoramento da morfologia costeira em setores da bacia potiguar sob influ?ncia da ind?stria petrol?fera utilizando geod?sia de alta precis?o e laser esc?ner terrestre." Universidade Federal do Rio Grande do Norte, 2014. http://repositorio.ufrn.br:8080/jspui/handle/123456789/13035.
Full textAbstract:
Made available in DSpace on 2014-12-17T14:09:18Z (GMT). No. of bitstreams: 1
AndreLSS_TESE.pdf: 5521921 bytes, checksum: f9408bc166edc779a453c6cc730acf4f (MD5)
Previous issue date: 2014-04-04The objective of this Doctoral Thesis was monitoring, in trimestral scale, the coastal morphology of the Northeastern coast sections of Rio Grande do Norte State, in Brazil, which is an area of Potiguar Basin influenced by the oil industry activities. The studied sections compose coastal areas with intense sedimentary erosion and high environmental sensitivity to the oil spill. In order to achieve the general objective of this study, the work has been systematized in four steps. The first one refers to the evaluation of the geomorphological data acquisition methodologies used on Digital Elevation Model (DEM) of sandy beaches. The data has been obtained from Soledade beach, located on the Northeastern coast of Rio Grande Norte. The second step has been centered on the increasing of the reference geodetic infrastructure to accomplish the geodetic survey of the studied area by implanting a station in Corta Cachorro Barrier Island and by conducting monitoring geodetic surveys to understand the beach system based on the Coastline (CL) and on DEM multitemporal analysis. The third phase has been related to the usage of the methodology developed by Santos; Amaro (2011) and Santos et al. (2012) for the surveying, processing, representation, integration and analysis of Coastlines from sandy coast, which have been obtained through geodetic techniques of positioning, morphological change analysis and sediment transport. The fourth stage represents the innovation of surveys in coastal environment by using the Terrestrial Laser Scanning (TLS), based on Light Detection and Ranging (LiDAR), to evaluate a highly eroded section on Soledade beach where the oil industry structures are located. The evaluation has been achieved through high-precision DEM and accuracy during the modeling of the coast morphology changes. The result analysis of the integrated study about the spatial and temporal interrelations of the intense coastal processes in areas of building cycles and destruction of beaches has allowed identifying the causes and consequences of the intense coastal erosion in exposed beach sections and in barrier islands
O objetivo da Tese de Doutorado foi o monitoramento da morfologia costeira em escala trimestral de trechos do Litoral Setentrional do Estado do Rio Grande do Norte, ?rea da Bacia Potiguar sob a influ?ncia das atividades petrol?feras. Trata-se de setores costeiros marcados por intensa eros?o sedimentar e de alta sensibilidade ambiental ao derramamento de ?leo. Para atingir o objetivo geral deste estudo, o trabalho foi sistematizado em quatro etapas. A primeira etapa apresenta a avalia??o das metodologias de aquisi??o de dados geomorfol?gicos utilizada na modelagem digital de eleva??o de praias arenosas a partir de dados obtidos na praia de Soledade, localizada no Litoral Setentrional do Rio Grande do Norte. A segunda etapa foi a amplia??o da infraestrutura geod?sica de refer?ncia para a realiza??o dos levantamentos geod?sicos da ?rea de estudo atrav?s da implanta??o de uma esta??o na ilha barreira de Corta Cachorro e de levantamentos geod?sicos de monitoramento para o entendimento do sistema praial com uso de an?lises multitemporal de LC e MDE. A terceira etapa consistiu na utiliza??o da metodologia geod?sica para o levantamento, processamento, representa??o, integra??o e an?lises de Linhas de Costa (LC) de litorais arenosos obtidos por t?cnicas geod?sicas de posicionamento, an?lise das altera??es morfol?gicas e transporte de sedimentos A quarta etapa foi definida pela inova??o de levantamentos em ambientes costeiros com a utiliza??o do Laser Esc?ner Terrestre (LiDAR) para avalia??o de um trecho submetido a intensa eros?o na praia de Soledade onde est?o instaladas infraestruturas da ind?stria petrol?fera, por meio de MDE de alta precis?o e acur?cia no modelamento das modifica??es na morfologia costeira. As an?lises dos resultados do estudo integrado das interrela??es espaciais e temporais dos intensos processos costeiros atuantes na ?rea ao longo de ciclos de constru??o e destrui??o das praias permitiram identificar as causas e consequ?ncias da intensa eros?o costeira em setores de praias expostas e ilhas barreiras
16
Fasesin, Kingsley, Ingrid Luffman, Eileen Ernenwein, and Arpita Nandi. "Improving Sinkhole Mapping Using LiDAR Data and Assessing Road Infrastructure at Risk in Johnson City, TN." Digital Commons @ East Tennessee State University, 2018. https://dc.etsu.edu/asrf/2018/schedule/30.
Full textAbstract:
Improving Sinkhole Mapping Using LiDAR Data and Assessing Road Infrastructure at Risk in Johnson City, TN.
Kingsley Fasesin1, Dr. Ingrid Luffman 1, Dr. Eileen Ernenwein 1 and Dr. Arpita Nandi1
1 Department of Geosciences, College of Arts and Sciences, East Tennessee State University, Johnson City, TN;
Abstract
Predicting infrastructure damage and economic impact of sinkholes along roadways requires mapping of sinkhole distribution and development of a model to predict future occurrences with high accuracy. The study is carried out to define the distribution of sinkholes in Johnson City, TN and risks they pose to roads in the city. The study made use of a 2.5 ft Digital Elevation Model (DEM) derived from Light Detection and Ranging (LiDAR) data acquired from Tennessee Geospatial clearing house (TNGIS) and an inventory of known sinkholes identified from topographic maps. Depressions were identified using the LiDAR-derived DEM by subtracting a filled-depressions DEM from the original study area DEM. Using a spatial join, mapped sinkholes were matched to depression polygons identified from the LiDAR-derived DEM. For all matched sinkhole-polygon pairs, three indices were calculated: circularity index, area ratio of minimum bounding rectangle, and proximity to train tracks and roads. The dataset was partitioned into training (70%) and validation (30%) subsets, and using the training dataset, thresholds for each index were selected using typical values for known sinkholes. These rules were calibrated using the 30% validation subset, and applied as filters to the remaining unmatched depression polygons to identify likely sinkholes. A portion of these suspected sinkholes were field checked. The future direction of this research is to generate a sinkhole formation model for the study area by examining the relationship between the mapped sinkhole distribution, and previously identified sinkhole formation risk factors. These factors include: proximity to fault lines, groundwater and streams; depth to bedrock; and soil and land cover type. Spatial Logistic Regression analysis will be used for model development, and results will be used to generate a sinkhole susceptibility map which will be overlain on the road network to identify the portions of interstate and state highways at risk of sinkhole destruction.
17
Ortiz, Peña Victor Alejandro, and Milos Dinic. "Satellite derived data to support flood modelling : An application to the Po River." Thesis, KTH, Hållbar utveckling, miljövetenskap och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-230889.
Full textAbstract:
Satellite derived data has become an essential input in hydraulic modelling. Digital ElevationModels (DEMs) derived from different sources through remote sensing techniques have become a powerful tool for poorly gauged regions. This paper analyses the capabilities of DEMS derived from Shuttle Radar Topography Mission (SRTM) and a Light Detection and Ranging (LiDAR) and compares their accuracy against each other in a 1D hydraulic model. The study tests two different methods for inferring the river bathymetry under the water surface level for the SRTM derived DEM in order to enhance its performance, the study further analyze the reliability of remotely sensed altimetry data derived from different satellite missions (TOPEX and ENVISAT) and its suitability to complement spaceborne topographic data in hydraulic modelling.
18
Eriksson, Alexander, and James Eklund. "Kvalitetsaspekter vid generering av triangulära nät baserade på punktmoln." Thesis, Högskolan i Gävle, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-21670.
Full textAbstract:
Light Detection and Ranging (LIDAR) är en teknik för att samla in data om terräng. Genom att använda dessa data kan man skapa olika terrängmodeller. Denna studie syftar till att undersöka hur olika procentuella reduceringar av ursprungsdata påverkar kvalitén hos genererade höjdmodeller i form av Triangular Irregular Network (TIN). Detta görs genom att med hjälp av statistiska metoder göra jämförelser mellan punkter i den genererade TIN modellen och motsvarande punkter i det ursprungliga LIDAR punktmolnet. Studien visar att, beroende på noggrannhetskrav och topografi, en så liten andel som 5 % av punkterna kan vara tillräckligt, samt att noggrannhetsförbättring vid användning av mer än 50 % av ursprungsdata inte kan motivera den ökade arbetsbelastningen för datahantering.
19
Depoy, Randy S. Jr. "UHF-SAR and LIDAR Complementary Sensor Fusion for Unexploded Buried Munitions Detection." Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1357843204.
Full text
20
Kniess, Ulrich. "Quantification de l'évolution de glissements de terrain argileux par des techniques de télédétection. Application à la région du Trièves (Alpes Françaises)." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00728238.
Full textAbstract:
Trois méthodes de télédétection (Lidar, interférométrie radar satellitaire et photogrammétrie aérienne) ont été appliquées pour quantifier les évolutions spatiales et temporelles de deux glissements argileux (Harmalière et Avignonet, situés dans la région du Trièves, Alpes françaises) en complément d'instrumentation in-situ. Une analyse géomorphologique a été réalisée à partir d'ortho-photos (depuis 1948) et du MNT Lidar filtré. Couplée à des reconnaissances géophysiques, elle a montré que la cinématique différente des deux glissements contigus était partiellement contrôlée par la paléotopographie sur laquelle s'est déposée la couche d'argile. La rugosité directionnelle a permis de distinguer les processus d'érosion résultant de mouvements gravitaires et de ravinement. Une technique de corrélation d'images adaptée aux MNT a été développée pour obtenir les vecteurs de déplacement 3D entre deux acquisitions Lidar (2006 - 2009), avec une attention particulière portée à l'évaluation de la qualité des mesures. La carte des déplacements obtenue montre que la zone la plus active du glissement de Harmalière entre 1981 et 2001 est maintenant relativement lente (déplacement <0.4 m en 3 ans), contrairement à d'autres zones proches montrant des mouvements importants atteignant 3m avec une composante rotationnelle. Pour le glissement d'Avignonet, les déplacements déduits augmentent généralement vers le pied du glissement et peuvent atteindre 1 m. La technique des réflecteurs permanents en interférométrie radar a permis de déterminer de nouvelles valeurs de taux de déplacements (entre 1992 et 2000) en 16 points du glissement, qui sont cohérentes avec les données GPS existantes. Le taux moyen de recul à long terme de l'escarpement principal a été estimé à 1-5 cm/an à Avignonet et entre 7 et 14 cm/an à l'Harmalière. La régression du glissement d'Avignonet semble contrôlée par l'érosion du sommet de la couche d'alluvions compactes reposant sur le substratum. La présence d'une paleovallée du Drac sous le pied du glissement de l'Harmalière pourrait expliquer cette différence de cinématique entre les deux glissements.
21
Dunn, Shanna K. "Analyzing Spatial Patterns in Reefscape Ecology Via Remote Sensing, Benthic Habitat Mapping, and Morphometrics." NSUWorks, 2009. http://nsuworks.nova.edu/occ_stuetd/234.
Full textAbstract:
A growing number of scientists are investigating applications of landscape ecology principles to marine studies, yet few coral reef scientists have examined spatial patterns across entire reefscapes with a holistic ecosystem-based view. This study was an effort to better understand reefscape ecology by quantitatively assessing spatial structures and habitat arrangements using remote sensing and geographic information systems (GIS).
Quantifying recurring patterns in reef systems has implications for improving the efficiency of mapping efforts and lowering costs associated with collecting field data and acquiring satellite imagery. If a representative example of a reef is mapped with high accuracy, the data derived from habitat configurations could be extrapolated over a larger region to aid management decisions and focus conservation efforts.
The aim of this project was to measure repeating spatial patterns at multiple scales (10s m2 to 10s km2) and to explain the environmental mechanisms which have formed the observed patterns. Because power laws have been recognized in size-frequency distributions of reef habitat patches, this study further investigated whether the property exists for expansive reefs with diverse geologic histories.
Intra- and inter-reef patch relationships were studied at three sites: Andavadoaka (Madagascar), Vieques (Puerto Rico), and Saipan (Commonwealth of the Northern Mariana Islands). In situ ecological information, including benthic species composition and abundance, as well as substrate type, was collected with georeferenced video transects. LiDAR (Light Detection and Ranging) surveys were assembled into digital elevation models (DEMs), while vessel-based acoustic surveys were utilized to empirically tune bathymetry models where LiDAR data were unavailable. A GIS for each site was compiled by overlying groundtruth data, classifications, DEMs, and satellite images. Benthic cover classes were then digitized and analyzed based on a suite of metrics (e.g. patch complexity, principle axes ratio, and neighborhood transitions).
Results from metric analyses were extremely comparable between sites suggesting that spatial prediction of habitat arrangements is very plausible. Further implications discussed include developing an automated habitat mapping technique and improving conservation planning and delimitation of marine protected areas.
22
Young, III James Russell. "An Evaluation of DEM Generation Methods Using a Pixel-Based Landslide Detection Algorithm." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/104863.
Full textAbstract:
The creation of landslide inventories is an important step in landslide susceptibility mapping, and automated algorithms for landslide detection will increasingly be relied upon as part of the mapping process. This study compares the effects of three different DTM generation methods on a pixel-based landslide detection algorithm developed by Shi et al. (2018) using a set of landslide-prone study areas in Pierce County, Washington. Non-parametric statistical analysis demonstrated that false-positive and false-negative rates were significantly different between DTM generation methods, showing that inpainting presents a more balanced error profile compared to TIN and morphological-based approaches. However, overall accuracy (kappa) rates were still very low overall, suggesting that geomorphometric curvature as an input needs to be processed in a different manner to make these types of pixel-based landslide detection algorithms more useful for landslide inventory database management.Master of Science
The creation of landslide inventories is an important step in landslide susceptibility mapping, and automated algorithms for landslide detection will increasingly be relied upon as part of the mapping process. This study compares the effects of three different DTM generation methods on a pixel-based landslide detection algorithm developed by Shi et al. (2018) using a set of landslide-prone study areas in Pierce County, Washington. Statistical analysis demonstrated that false-positive and false-negative rates were significantly different between DTM generation methods, showing that inpainting presents a more balanced error profile compared to TIN and morphological-based approaches. However, overall accuracy rates were still very low overall, suggesting that curvature as an input needs to be processed in a different manner to make these types of pixel-based landslide detection algorithms more useful for landslide inventory database management.
23
Montane, Juana Maria. "Geophysical Analysis of a Central Florida Karst Terrain using Light Detection and Ranging (LIDAR) and Ground Penetrating Radar (GPR) Derived Surfaces." FIU Digital Commons, 2001. http://digitalcommons.fiu.edu/etd/42.
Full textAbstract:
Airborne LIDAR (Light Detecting and Ranging) is a relatively new technique that rapidly and accurately measures micro-topographic features. This study compares topography derived from LIDAR with subsurface karst structures mapped in 3-dimensions with ground penetrating radar (GPR). Over 500 km of LIDAR data were collected in 1995 by the NASA ATM instrument. The LIDAR data was processed and analyzed to identify closed depressions. A GPR survey was then conducted at a 200 by 600 m site to determine if the target features are associated with buried karst structures. The GPR survey resolved two major depressions in the top of a clay rich layer at ~10m depth. These features are interpreted as buried dolines and are associated spatially with subtle (< 1m) trough-like depressions in the topography resolved from the LIDAR data. This suggests that airborne LIDAR may be a useful tool for indirectly detecting subsurface features associated with sinkhole hazard.
24
Yu-WeiLiu and 劉囿維. "Quality Assessment of DEM Generation From Airborne LiDAR Data." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/04064303682794660930.
Full textAbstract:
碩士國立成功大學
測量及空間資訊學系碩博士班
98
Airborne LiDAR has become the primary technology of DEM generation. In order to produce DEM from airborne LiDAR data, the major process is filtering non-ground points. Mane filtering methods have been developed. All filters are designed to keep as many correct ground points as possible. However, there is no perfect filter yet. Every filter more or less misclassifies some non ground points to ground point, or the other way round. Owing to the widespread application of DEM, how to assess the quality of a DEM product is an important topic. For this reason, the paper investigates the quality influences of process of DEM generation from airborne LiDAR data. The quality of DEM generated from airborne LiDAR data is conventionally assessed with the classification accuracy of point cloud filtering, or checking the elevation differences of the sampling points. This paper focuses on the study of quality control of DEM generation process. Three methods applied to assess DEM quality were investigated using ISPRS LiDAR test datasets. The first method is the evaluation of filtering accuracy. The filtered results are evaluated using the error matrix and the corresponding statistics indices. The second method is elevation accuracy. The DEM difference between a generated DEM and the reference dataset is computed for the evaluation. The third method is to locate large errors using the normalized DEM differences in which DEM differences are normalized using terrain gradients. The combination of the three methods is suggested for the quality control of DEM generation from airborne LiDAR data. The experiments conducted in this paper mainly investigate three issues about the quality control of DEM generation from airborne LiDAR data. The first issue is the suitable of quality assessment methods of DEM generation. The experimented results suggest that one can not solely rely on statistics indices of point cloud classification to assess DEM quality. The RMSE are histogram of DEM difference should be investigated as well. The second issue is that the performance of a point cloud filter may vary subject to the terrain types. After all, none of filter methods has been claimed to be perfect. Manual editing is, therefore, suggested to improve DEM quality. Finally, how manual editing may improve the quality of DEM generation is studied. In accordance with the demand of DEM quality, a producer need to take the time and labor consumption into account.
25
Goulden, Tristan. "SENSITIVITY OF TERRAIN ATTRIBUTES, WATERSHED ATTRIBUTES, AND SWAT DERIVED HYDROLOGICAL OUTPUTS TO LIDAR DERIVED DEM UNCERTAINTY." 2013. http://hdl.handle.net/10222/38534.
Full textAbstract:
This research analyzes the sensitivity of watershed attributes, and hydrological outputs to LiDAR derived DEM uncertainty introduced through spatial resolution, and LiDAR measurement errors. Sensitivity of watershed attributes to spatial resolution was determined through a scaling analysis at three sites; Mosquito Creek, Scotty Creek and Thomas Brook, with DEMs ranging from 1 to 50 m. Results at Scotty Creek showed the highest sensitivity of watershed area to spatial resolution, due to subtle changes in elevation which were below DEM uncertainty. Validation of the stream length at Thomas Brook showed discrepancies of 3.7 to 24.1% for the 1 to 50 m DEMs, compared to independent field observations. Sensitivity of SWAT derived hydrological outputs to DEM spatial resolution were determined through a scaling analysis of DEMs (1 - 50 m) at Thomas Brook watershed, over a five year simulation period. Results indicated monthly water yield was insensitive to DEM resolution, unless a change in area was also present. Sediment yield from the 50 m DEM showed a 24% reduction compared to the 1 m DEM. The 5 - 50 m DEMs also showed a reduction in channel deposition of 45 - 90 t, compared to the 1 m DEM.
Sensitivity of terrain attributes, watershed attributes and hydrological outputs to LiDAR measurement errors were determined at the Thomas Brook watershed through the propagation of LiDAR sensor measurement errors with Monte Carlo simulations. Results showed that the uncertainty in the DEM, slope, and aspect were below 0.06 cm, 1.5° and 24.1° in 97.5% of grid cells, respectively. Watershed area and stream length resulted in relative standard deviations of <1% and 1.5%, respectively. However, sensitivity of watershed area increased in regions with elevation changes below DEM uncertainty and stream length uncertainty increased with decreasing stream length. SWAT simulated flow and sediment showed minor sensitivity to LiDAR measurement error in high flow months, and increased as flow decreased. Simulated sediment showed higher sensitivity to LiDAR measurement errors than flow, due to changes in the HRU slope class, which can shift the dominant HRU (Hydrological Response Unit) if a minimum HRU threshold area is implemented.
26
Cheng, Pang-ning, and 鄭邦寧. "Wavelets-Based Method for Determining DEM by Using Airborne LiDAR Data." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/04571837453362851711.
Full textAbstract:
碩士國立成功大學
測量及空間資訊學系碩博士班
95
Generating DEM by using airborne LiDAR data has two main problems: 1.How to select the terrain points from complex LiDAR data set, 2.How to increase the efficiency of LiDAR point classification / filtering. According to the above-mentioned problems, this study proposes a wavelets-based method for classifying LiDAR points in a local area to determine DEM. The method can not only well filter out the noise points, but also determine reliably a real and complex fractal surface. Considering the phenomenon of Gibbs effect located within the edge areas of the buildings, the method utilises geodesic dilation, the height difference and height difference increment between terrain points and non-terrain points, and then re-selects LiDAR points by generating a reference surface to select more reliable terrain points. Besides, digital aerial color images can be used for selecting more reliable terrain points in vegetation areas. Finally, those terrain points selected by the method are used to generate the DEM. Also, a method is proposed to exclude those non-terrain points in a bridge region. The concept of bridge detection is based on the geometry properties of the bridge surface, such as bridge surface is higher than its neighboring ground surface, and the bridge surface is often a flat area. A point scanning method is presented to sort the seeds located on the bridge surface. These seeds can be adopted for region growing process. Then all non-terrain points within the bridge area can be found.
27
Chang, Chia-Hao, and 張家豪. "Identification of Landslide features using Back-Propagation Neural Network on LiDAR DEM." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/a3ys72.
Full textAbstract:
碩士國立宜蘭大學
土木工程學系碩士班
106
The prediction of a landslide is a difficult task because it requires a detail study of past activities using a complete range of investigative methods to determine the changing condition. In this research, first step, LiDAR 1-meter by 1-meter resolution of digital elevation model (DEM) was used to generate six environmental factors of landslide. Then, Back-Propagation Neural Network (BPNN) was adopted to identify scarp, landslide areas and non-landslide areas. The BPNN uses 6 environmental factors in input layer and 1 output layer. Moreover, 6 landslide areas are used as training areas and 4 landslide areas as test areas in the BPNN. The hidden layer are set to be 1 and 2; the hidden layer neurons are set to be 3, 4, 5, 6, 7 and 8; the learning rates are set to be 0.01, 0.1 and 0.5. When using 1 hidden layer with 7 neurons and the learning rate was set to be 0.5, the best result of network training root mean square error is 0.0382. Finally, evaluation of BPNN classification accuracy using the confusion matrix the result shows that the overall accuracy is 96.3% and the Kappa value is 0.821.
28
Tsai, Jian-Cheng, and 蔡建成. "Analysis Of The DEM Quality Made Of Aerial Images Simultaneously With Airborne Lidar." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/88428385035555326317.
Full textAbstract:
碩士國立交通大學
土木工程系所
97
Airborne LiDAR contribute a large number of 3D point clouds, which is one of the main methods to derive DEM. However, the aerial image taken simultaneously with an airborne lidar is potential for producing DEM. Focusing on provide orthoimage simultaneously, airborne LiDAR equipped with digital middle format frame camera to obtain images, which is potential for producing DEM. In consequence, comparing with the airborne lidar, this study using riverway survey data of Taan River Lan-Shi bridge area analyses the quality of DEM that using automated matching aerial images, as well as the influence of height accuracy caused by radial distortion. It is shown that the RMSE of the height difference value is 0.5528 m in the Well -defined point anaysis, while it is 1.4685~7.9421 m in 10° slope in the slope and error analysis. Steeper slope with the higher error is also proved. In vegetation coverage and error analysis, the RMSE of the height difference value in plantations and natural forest is 1.0046m, 1.4355 respectively. The influence caused by the radial distortion was demonstrated. Comparing the heights resulting from automated matching with the corrected and un-corrected images,the bias is -11.95m, and the standard deviation is 16.16m. Comparing with the airborne lidar, the RMSE from the corrected image is 3.56m, while 19.80m for the un-corrected.
29
Chou, Fu-Chen, and 周富晨. "An Adaptive Point Cloud Filtering Algorithm for DEM Generation from Airborne Lidar Data." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/07520162336469440714.
Full textAbstract:
碩士國立成功大學
測量工程學系碩博士班
92
DEM generation is the primary application of airborne Lidar. The point cloud provided by airborne Lidar not only represents the terrain surface, but also contains buildings, vegetation, or other ground objects. The major process of generating DEM from airborne Lidar is to filter out non-ground points from the point cloud data. The purpose of this study is to propose an adaptive filtering algorithm for DEM generation using airborne Lidar data. The filtering algorithm is based on the principle of morphological filtering theory. To make the algorithm adaptive, a 3-D grid structure is used to organize point cloud data, so that the trend surface and local slope of the ground can be estimated. The algorithm is carried out in two steps: the rough filtering and the detailed filtering. The rough filtering is to remove the points far away from the trend surface by the pre-defined threshold. Then the remained points will be filtered again using estimated local slope in the detailed filtering. The two-step filtering can be performed iteratively, so that the trend surface is modified gradually in each step of iteration to obtain the optimal result. The feasibility of the proposed algorithm is tested by using some test data with different characteristics of topography covering Hsinchu County. The algorithm is proud to be effective and practicable in most test cases, but in some cases some ground points in the rough terrain may be over-filtered. To assure the quality of DEM product, manual check and editing is still necessary against the improper filtering results.
30
Dhun, Kimberly Anne. "Application of LiDAR DEMs to the modelling of surface drainage patterns in human modified landscapes." Thesis, 2011. http://hdl.handle.net/10214/2969.
Full textAbstract:
Anthropogenic infrastructure such as roads, ditches and culverts have strong impacts on hydrological processes, particularly surface drainage patterns. Despite this, these structures are often not present in the digital elevation models (DEMs) used to provide surface drainage data to hydrological models, owing to the coarse spatial resolution of many available DEMs. Modelling drainage patterns in human-modified landscapes requires very accurate, high-resolution DEM data to capture these features. Light Detection And Ranging (LiDAR) is a remote sensing technique that is used for producing DEMs with fine resolutions that can represent anthropogenic landscapes features such as human modifications on the landscape such as roadside ditches. In these data, roads act as a barrier to flow and are treated as dams, where on the ground culverts and bridges exist. While possible to locate and manually enforce flow across these roads, there is currently no automated technique to identify these locations and perform flow enforcement. This research improves the modelling of surface drainage pathways in rural anthropogenic altered landscapes by utilizing a novel algorithm that identifies ditches and culverts in LiDAR DEMs and enforces flow through these features by way of breaching. This breaching algorithm was tested on LiDAR datasets for two rural test sites in Southern Ontario. These analyses showed that the technique is an effective tool for efficiently incorporating ditches and culverts into the hydrological analysis of a landscape that has both a gradient associated with it, as well as a lack of densely forested areas. The algorithm produced more accurate representations of both overland flow when compared to outputs that excluded these anthropogenic features all together.
31
Ho, Hsin-Yu, and 何心瑜. "The Production Process and Quality Management Schemes for DEM Generation from Airborne LiDAR Data." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/13907033581496801008.
Full textAbstract:
碩士國立交通大學
土木工程系所
94
Airborne LiDAR has become one of the primary methods used for DEM generation. This study investigates the production process and quality management scheme for DEM generation from airborne LiDAR data. The quality of airborne LiDAR produced by DEM is currently evaluated by identifying the planimetric and height position accuracies with ground checkpoints. Because there are only a limited number of checkpoints, and the process is usually conducted during the final stage, a step-by-step quality management scheme during the flow of DEM production would be beneficial. In this study, the production process is investigated first. Subsequently, a quality check scheme is designed. Based on different application requirements, the standard of the threshold values may be different. However, reference values are provided in this study. Several important issues, including point density, filtering, and manual editing, are studied together with the height accuracy validation. It has been determined that the distribution and density of ground points in the original point cloud greatly influence the DEM production. If the amount of points on the ground is not sufficient, manual editing may improve the overall data quality. However, the quality of the final product is still in doubt. The last step in the DEM production is the transformation from the ellipsoid height system into an orthometric height system. The performance of several currently available geoid models of Taiwan is also evaluated. It is found that models with differential leveling benchmarks included in the formation process perform better.
32
Yeh, Chih-Hsiang, and 葉致翔. "Sedimentary Strata Mapping and Dip Slope Auto-tracing with LiDAR DEM Using Self-developed Geoprocessing Toolsets." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/dw48tz.
Full textAbstract:
博士國立臺灣大學
土木工程學研究所
105
Traditional geological mapping may be hindered by rough terrain and dense vegetation resulting in obscuration of geological details. Consequently, stratum units and mainly topographic features such as dip slopes are often mapped at coarse scales and simplifications. The advent of airborne Light Detection and Ranging (LiDAR) offers a very precise digital elevation model (DEM). However, its full potential in complementing traditional geological mapping remains to be explored using 3D rendering techniques. This study uses two types of 3D images which differ in imaging principles to further explore the finer details of sedimentary terrain. Our purposes are to demonstrate detailed strata mapping with LiDAR 3D images, and to develop an auto-tracing method with LiDAR data for improving existing dip-slope mapping using an example from an about 46 km2 sedimentary area of the north bank of Keelung River, northern Taiwan. This area located between two densely populated cities has been developed for transport infrastructures and large-scale communities, which has resulted in many dip-slope landslides. The research process of this study can be divided two phases. In the first phase, we use LiDAR 3D images to derive 19 LiDAR-based strata boundaries and 39 measurements of LiDAR-derived strike and dip that are located in areas where terrain is difficult to access for generating a 1:2,500-scale strata map. In the second phase, we follow the above result of LiDAR-based strata boundaries to derive a high-precise GIS raster of geological attitudes for building an auto-tracing process in dip-slope mapping, and further identifying the daylighted dip slopes along the freeway. By using self-developed geoprocessing toolsets programmed by Python, we enhance efficiency of LiDAR data processing and practice an automatic processing in dip-slope mapping. For demonstration, we conducted fieldworks to validate the correctness of LiDAR-derived strike and dip, and compared and validated our dip-slope mapping results against two government-funded visually interpreted dip-slope maps. The proposed practices and approaches in sedimentary strata mapping and dip slope auto-tracing should greatly improve the quality, the accuracy and the efficiency in the generation of maps in the future.
33
Jaroš, Jakub. "Detekce linií terénní kostry z dat leteckého laserového skenování." Master's thesis, 2011. http://www.nusl.cz/ntk/nusl-312760.
Full textAbstract:
The objective of the thesis is to design a new detection method of terrain skeleton lines from airborne laser scanning data. The theoretical part provides a brief introduction to airborne laser scanning issue. There are presented major principles of the technology and procedures applied to create digital terrain model from laser data. There is also described an application of airborne laser scanning in the area of the Czech Republic in detail and follows an exact specification of key terms of the thesis. From the geomorphology, topography and geoinformatics point of view there are defined especially terms like terrain skeleton lines, breakline, valley and ridge. Literary research consists of the summary of already published method of breakline detection. There are algorithms focused on data processing in form of original point cloud as well as algorithms focused on processing data in the raster form. Primary goal of the theoretical part is to express major principles of already published method of detection. The practical part firstly introduces data that are used further in the thesis. The objective of the thesis is a description of a new method of detection of terrain skeleton lines. The method processes laser data converted into raster form and it is based on the analysis of transverse elevation profile...
34
Wu, Kahn-Bao, and 吳康寶. "Automatic Detection of Potential Deep-Seated Landslide Features from LiDAR DEM Using Object-Oriented Analysis with Support Vector Machine." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/8cp5q8.
Full textAbstract:
碩士國立臺灣大學
土木工程學研究所
107
In Taiwan, landslides are constantly triggered by earthquakes, typhoons, and heavy rains. In August, 2009, Typhoon Morakot caused severe destruction and hundreds of people’s deaths or injuries. One of the most affected areas, Siaolin village at Kaohsiung city, was buried by deep-seated landslides in Taiwan. In order to prevent the same disaster from happening again, the detection of potential deep-seated landslide features has become the primary task of preventing such disasters, and providing information before the disaster happens. Terrified by such an event, government started a program for manually detecting and mapping potential deep-seated landslides and features of potential deep-seated landslide near roads or villages. The light detection and ranging (LiDAR) digital elevation models (DEMs) with 1 m resolution, aerial photos and deep-seated landslide inventory maps were produced from the program. With these useful data of deep-seated landslides produced from the program, this study proposes a novel approach employing object-oriented analysis to segment LiDAR DEM and followed by labelling the segmentation, applying support vector machine to classify the scarp of landsides, using connected component labeling with threshold to refinement the classification result and marking the precise positions of the scarp features. This research proposes method with LiDAR DEM provided only is able to efficiently detect potential deep-seated landslide features with satisfactory results through an automatic work scheme. The result provides the marked regions which are contain features of potential deep-seated landslide and the position of the scarps. It can be applied to boundaries of potential deep-seated landslide demarcation and production of the landslide inventory map.
35
DiFebo, Antonio. "On developing an unambiguous peatland classification using fusion of IKONOS and LiDAR DEM terrain derivatives – Victor Project, James Bay Lowlands." Thesis, 2011. http://hdl.handle.net/10012/5962.
Full textAbstract:
Bogs and fens, which comprise > 90% of the landscape near the De Beers Victor diamond mine, 90 km west of Attawapiskat, ON, provide different hydrological functions in connecting water flow pathways to the regional drainage network. It is essential to define their distribution, area and arrangement to understand the impact of mine dewatering, which is expected to increase groundwater recharge. Classification was achieved by developing a technique that uses IKONOS satellite imagery coupled with LiDAR-derived DEM derivatives to identify peatland classes. A supervised maximum likelihood classification was performed on the 1 m resolution IKONOS Red/Green/Blue without the infrared (RGB) and with the infrared (IR_RGB) band to determine the overall accuracy prior to inclusion of the DEM derivatives. Confusion matrices indicated 62.9% and 65.8% overall accuracy for the RGB and IR_RGB, respectively. Terrain derivatives were computed from the DEM including slope, vertical distance to channel network (VDCN), deviation from mean elevation (DME), percentile (PER) and difference from mean elevation (DiME). These derivatives were computed at a local (15-cell grid size) and meso (250-cell grid size) scale to capture terrain morphology. The mesoscale 250-cell grid analysis produced the most accurate classifications for all derivatives. However, spectral confusion still occurred (regardless of scale) most frequently in the Fen Dense Conifer vs. Bog Dense Conifer classes and also in the Bog Lichen vs. Bog Lichen Conifer. Despite this confusion, by combining the larger scale LiDAR DEM derivatives and the IKONOS imagery it was found that the overall classification accuracy could be improved by 13%. Specifically, the DiME derivative combined with the multispectral IKONOS (IR_RGB) produced an overall accuracy of 76.5%, and increased to 83.7% when Bog Lichen and Bog Lichen Conifer were combined during a post hoc analysis. This classification revealed the landscape composition of the North Granny Creek subwatershed, which is divided into north and south. The north portion comprises 67.4% bog, 13.6% fen and 18.9% water class, while the south is 63.7% bog, 15.2% fen and 21.1% water class. These proportions provide insight into the hydrology of the landscape and are indicative of the storage and conveyance properties of the subwatershed based on the percentage of bog, fen, or open water.