Academic literature on the topic 'Portable photogrammetry'

Disposal of the UK's legacy nuclear waste is the biggest challenge facing the industry at present. There is currently no long term storage facility in the UK and the inventory is continually growing. This project investigates the role that digital geoscientific data collection, analysis and modelling techniques play in the search for, and development of, a Geological Disposal Facility (GDF), critically analyses classical techniques and new, digital methodologies to assess what their impact would be on any site investigation. The Borrowdale Volcanic Group outcrop in Cumbria, NW England was chosen as it provides an analogue to a higher-strength crystalline basement setting for a GDF. Terrestrial lidar and photogrammetric surveys were conducted at four locations around the study area. These provided information on the fracture geostatistics which are the main fluid migration pathways in the subsurface in the BVG. The mechanics of deformation are identified by analysing the clustering of data points via digital stereonet analysis. The analysis shows the rocks sampled are highly fractured and their orientations and dips reflected the extensional tectonism experienced in the area. These are in the form of adjacent sets trending broadly NNE-SSW and NNW-SSE at very high angler dips (~70 degrees). A new workflow developed for this work demonstrates how a potential site's fracture statistics, and indeed the 3D geology, should be investigated as part of future GDF site investigations. Areas of complex geology such as the BVG present many difficulties in interpretation and analysis due to the poorly constrained polyphase nature of the deformation. These complexities make characterisation and modelling highly problematic, and as such, areas of simpler geology should be investigated first. Assessments which were based on early geological studies using traditional field data collection techniques underestimated the impact of heterogeneity on fluid flow migration modelling within the subsurface. This suggests that, should a GDF should be developed in such a geological setting, huge difficulties may be encountered. These will be associated with the development of performance assessments and safety cases which are typically based on geological models that should use such complex data. In addition to this, datasets collected using digital methods are a powerful visualisation tools for communication of complex geology, that can be utilised in stakeholder engagement activities that will form a key part of any GDF development process.

The presence of subseismic scale faulting within high porosity sandstone reservoirs and aquifers represents a significant source of uncertainty for activities such as hydrocarbon production and the geologic sequestration of carbon dioxide. The inability to resolve geometrical properties of these smaller scale faults, such as size, connectivity and intensity, using conventional subsurface datasets (i.e. seismic reflection tomography, wireline log and core), leads to ambiguous representations within reservoir models and simulators. In addition, more fundamental questions still remain over the role of cataclastic faults in the trapping and transfer of mobile geofluids within the subsurface, particularly when two or more immiscible fluid phases are present, as is the case during hydrocarbon accumulation, waterflood operations and CO2 injection. By harnessing recent developments in 3D digital surface and volume imaging, this study addresses uncertainties pertaining to the geometrical and petrophysical properties of subseismic scale faults within porous sandstone reservoirs. A novel structural feature extraction and modelling framework is developed, which facilitates the restoration of fault and fracture architecture from digital rock surface models. This framework has been used to derive volumetric fault abundance and connectivity from a normal sense array of cataclastic shear bands developed within high porosity sandstones of the Vale of Eden Basin, UK. These spatially resolved measures of discontinuity abundance provide the basis for the geostatistical extrapolation of fracture/fault intensity into reservoir modelling grids, which promises the introduction of a much higher degree of geological realism into discrete fracture network models than can currently be achieved through purely stochastic methods. Moreover, by establishing spatial correspondences between volumetric faulting intensity and larger scale features of deformation observed at the study area (cataclastic shear zones), the work demonstrates the potential to relate reservoir equivalent measures of fault or fracture abundance obtained from outcrop to seismically resolvable structures within the subsurface, aiding the prediction of reservoir structure from oilfield datasets. In addition to the derivation of continuum scale properties of sub-seismic scale fault networks, a further investigation into the pore-scale controls which govern the transfer of fluids within cataclised sandstones has been conducted. Through X-ray tomographic imaging of experimental core flood (scCO2-brine primary drainage) through a cataclastic shear band bearing sandstone, insights into the influence that variations in fault structure exert over the intra-fault drainage pathway of an invading non-wetting fluid have been gained. Drainage across the fault occurs as a highly non-uniform and non-linear process, which calls into question the practice of using continuum methods to model cross fault flow. This work has also provided an improved understanding of the role that high capillary entry pressure cataclised regions play in modifying pore-fluid displacement processes within the surrounding matrix continuum. In particular, the high sweep efficiency and enhanced non-wetting phase pore-wall contact relating to elevated phase pressure observed during drainage points towards favourable conditions for wettability alteration within cataclised sandstones. This is likely to negatively impact upon the effectiveness of oil recovery and CO2 sequestration operations within equivalent reservoir and aquifer settings.

Reducing the soil impact of forest operations is a priority for improving sustainable forest management. Logging activities may alter soil in terms of both compaction and rutting. The overall aim of this thesis was to use an emerging methods approach to summarize how ground-based logging systems affect the soil in different working conditions. The thesis is based on four studies: the first applied a meta-analytic approach to machinery-induced soil compaction and its effect on the growth of forest plants; two studies tested new methods of rutting estimation after the trafficking of forest machinery; the last study addressed soil damage caused by skidding and forwarding under specific work conditions. The studies investigated the effects of ground-based extraction systems, including physical soil parameters for assessing compaction (i.e., bulk density and soil penetration resistance) and emerging methods for rutting measurements (i.e., 3D soil models obtained by portable laser scanning and Structure from Motion derived from photogrammetry, with images collected from a ground-based stand or higher altitudes by drones). The results of the meta-analysis showed the effects of soil compaction caused by machine trafficking on both morphological and physiological plant characteristics, especially in fine-textured soil. The most notable results of the other studies highlighted the irrelevant role of driving direction on soil damage during forwarding on a 25% slope. On the contrary, to reduce soil compaction, downhill skidding is preferable to uphill skidding. The results showed that low tyre pressure may mitigate the effects of forwarding on soil compared with higher tyre inflation pressure (i.e., 150 kPa vs. 350 kPa). The pressure on the ground caused by logging vehicles affects the wheel tracks, but to some extent, also the soil between the tracks. In general, the area affected by soil impacts was larger in skidding than forwarding due to the effect of dragged logs. Rutting estimation with photogrammetry and portable laser scanners showed promising results in terms of high-resolution data. It also reduced the time necessary for field surveys and obtaining accuracy compared to manual measurements. Nevertheless, the presence of free water in ruts or brush mats can affect the accuracy of results.

Precision forestry is a new approach for more sustainable forest management. Modern technologies are important to the development of new tools and applications to conduct site-specific management practices. 3D remote sensing technologies are new tools and have new applications useful for improving the data collection, work efficiency and quality of forest information that can be used to take better management decisions. This thesis is aimed at assessing the use of 3D data to develop new tools and procedures useful for forest inventories and for the estimation of soil disturbances caused by forest operations. In so doing, this study attempts to close the gaps underlined by previous studies. The thesis is divided into two main sections. The first one comprises the studies I, II, and III related to forest inventory optimization, while the second section comprises the studies IV and V related to estimation of soil disturbances caused by forest operations. Study I demonstrates how a 3D point cloud acquired by a Terrestrial Laser Scanner (TLS) and a Hand-Held Mobile Laser Scanner (HMLS) can be used to automatically derive forest single tree variables such as diameter at breast height (DBH) and tree position (TP). Moreover, the study underlines how the integration of TLS with Airborne Laser Scanner (ALS) point clouds improves the estimation of tree top height (H) and crown base projection (CPA). In study II a novel approach is presented for the extraction of explanatory variables from unmanned aerial vehicle (UAV) 3D photogrammetric data for predicting forest biophysical properties without relying on a digital terrain model. This study assesses the use of DTM-independent variables to predict forest biophysical proprieties using as a benchmark two more traditional sets of variables: (i) height and density variables from UAV photogrammetric data normalized using a DTM acquired using airborne laser scanning (ALS) (Image-DTMALS variables), and (ii) height and density variables extracted from normalized ALS data (ALS variables). We obtained comparable results between the models developed with DTM-independent models and the ones obtained with the other two types of variables (i.e. Image-DTMALS and ALS) to predict: Growing Stock Volume (V), Basal Area (G), Number of trees (N), Dominant Height (Hdom) and Lory’s height (Hl). Study III used the new set of DTM-independent variables developed in study II to predict area-based (ABA) forest structure variables (e.g. V, G, Mean Diameter (DBHmean), Gini coefficient of DBH (Gini), standard deviation of DBH(σdbh), Hdom, Hl and standard deviation of H (σh)) using as benchmarks the variables from ALS. The results underline comparable results between the two types of metrics in the estimation of forest structure variables. Moreover, the models developed with DTM-independent metrics were used to create two maps of two forest structure indices. In study IV and V we tested the utility of multi-temporal high resolution DTM derived by Personal Laser Scanner (PLS) (IV) and by close range photogrammetry (V) to measure and quantify soil disturbances caused by forest operation. These studies underline how multi-temporal high resolution (DTM) can be used to quantify rut deep, bulges, and soil volume changes. In conclusion, 3D RS data appears useful in the development of new methods to collect and measure forest ecosystem components such as vegetation and soils