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Ilehag, Rebecca. "Exploitation of Digital Surface Models from Optical Satellites for the Identification of Buildings in High Resolution SAR Imagery". Thesis, KTH, Geoinformatik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-191203.
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Interpreting a Synthetic Aperture Radar (SAR) image and detecting buildings can be a difficult task visually. In order acquire an overview of an area that has been affected by a disaster, such as an earthquake, SAR is useful due to its independence of weather conditions and the time of the day. GeoRaySAR, a simulator that has been developed by German Aerospace Center (DLR) and the Technical University of Munich (TUM), uses prior knowledge about the geometry extracted, from e.g. a Digital Surface Model (DSM), in order to identify buildings in high resolution SAR data. The simulator has previously utilized DSMs generated from Light Detection And Ranging (LiDAR) data with a vertical and horizontal resolution of 0.1 meters and 1 meter respectively without vegetation. However, DSMs of such high quality is not available everywhere. The objective of this thesis is to evaluate DSMs generated from high-resolution optical data for identifying building in high resolution SAR data in GeoRaySAR. Specifically, images from the spaceborne sensor WorldView-2 have been utilized in this thesis for the extraction of the geometry. The DSMs have been preprocessed in terms of removal of vegetation and reduction of the noise level. The SAR images, acquired from TerraSAR-X, were utilized in GeoRaySAR in order to detect buildings with the assistance of the DSM. An image size limitation that existed in GeoRaySAR has been addressed by adding tiling, which is based on the size of the study scene. Normalized DSM (nDSM) can be determined by calculating the difference between a DSM and a DTM. A nDSM, that received some adjustments, was used as input to GeoRaySAR and compared with the results from the normal DSM. Study areas in three cities, Munich, London and Istanbul, have been used to determine the advantages and limitations of GeoRaySAR and the impact the quality of the DSM has on the building extraction results. The results indicate that building extents can be detected with DSMs generated from optical data with various success, dependent on the quality of the DSM and on which incidence angle the SAR image was acquired in. The ability to interpret a scene increases with the usage of DSMs of higher quality and with SAR images taken in less steep incidence angles. The building DSM depends heavily on the quality of the DTM, but indicates good results and little data loss in study scenes where the DTM successfully removed all objects above ground.
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Zhang, Li Zhang Li. "Automatic digital surface model (DSM) generation from linear array images /". [S.l.] : [s.n.], 2005. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=16078.
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Gui, Xinyuan. "Building Boundary Sharpening In The Digital Surface Model Using Orthophoto". The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1566199054184572.
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Macay, Moreira José Miguel. "Using photogrammetric Digital Surface Model in LiDAR software for creating Three Dimensional Buildings". Thesis, Högskolan i Gävle, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-14724.
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The way of representing Earth has changed; two dimensional (2D) maps have turned into three Dimensional (3D) representations. There are many studies in order to create 3D city maps as well as areas where these are applied such as 3D cadastral, 3D visualization and flood simulation, etc. These can be created with the aid of different data sources using photogrammetric Digital Surface Model (DSM) derived from image matching and from Light Detection and Ranging (LiDAR) point clouds or both of them combining orthophotos and building footprints. Several software has been developed to ease and speed up this process. In this study, a current state-of-the art in the 3D city modeling with particular interest to commercial software was analyzed. DSMs from image matching (Satellite and Airborne) were used in order to create a 3D city model of Trento, Italy. The objectivewas to examine the degree of automation and the computation time of two available software: Feature Manipulation Engine (FME) and Building Reconstruction (BREC). Other problem such as the quality of the DSM needed would be discussed for each software and the results would be compared to those achieved using LiDAR data. Recommendations and possible problems would also be addressed. In order to create a 3D city model, the ALDPAT software (Airborne LiDAR Data Processing and Analysis Tool) has been used to separate the ground regions (Digital Terrain Model, DTM) from the man-made objects and trees (Normal Digital Surface Model, nDSM). FME and BREC software have been used to reconstruct the 3D city model. The output results from FME and BREC have been analyzed qualitatively and quantitatively. The comparison between the models generated from photogrammetric and LiDAR DSMs have been performed. The results show that buildings generated by satellite images have poorest quality compared with buildings from LiDAR and airborne data. In particular, the performed tests will be shown that among the Level of Details (LoD), a LoD1 and LoD2 3D city models can be generated using a DSM by image matching. A deeper study should be done in order to analyze the level of detail qualitatively.
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Ataseven, Yoldas. "Digital Surface Models From Spaceborne Images Without Ground Control". Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614995/index.pdf.
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Generation of Digital Surface Models (DSMs) from stereo satellite (spaceborne) images is classically performed by Ground Control Points (GCPs) which require site visits and precise measurement equipment. However, collection of GCPs is not always possible and such requirement limits the usage of spaceborne imagery. This study aims at developing a fast, fully automatic, GCP-free workflow for DSM generation. The problems caused by GCP-free workflow are overcome using freely-available, low resolution static DSMs (LR-DSM). LR-DSM is registered to the reference satellite image and the registered LR-DSM is used for i) correspondence generation and ii) initial estimate generation for 3-D reconstruction. Novel methods are developed for bias removal for LR-DSM registration and bias equalization for projection functions of satellite imaging. The LR-DSM registration is also shown to be useful for computing the parameters of simple, piecewise empirical projective models. Recent computer vision approaches on stereo correspondence generation and dense depth estimation are tested and adopted for spaceborne DSM generation.
The study also presents a complete, fully automatic scheme for GCPfree DSM generation and demonstrates that GCP-free DSM generation is possible and can be performed in much faster time on computers. The resulting DSM can be used in various remote sensing applications including building extraction, disaster monitoring and change detection.
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Malinowski, Roman. "Uncertainty characterisation in stereophotogrammetry using satellite images". Electronic Thesis or Diss., Compiègne, 2024. http://www.theses.fr/2024COMP2842.
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Actuellement, les Modèles Numériques de Surface (MNS) sont nécessaires pour de nombreuses applications, telles que la gestion des ressources en eau, le suivi de la biomasse, l’évaluation des dommages causés par les catastrophes naturelles ou la planification urbaine. Les MNS peuvent principalement être produits par interférométrie Radar, photogrammétrie ou en utilisant des instruments LiDAR. Dans ce contexte, le CNES et Airbus préparent le lancement de la constellation de satellites CO3D afin d’assurer la production massive de MNS à haute résolution par photogrammétrie. Fournie avec le MNS, une carte de performance permettra de caractériser les erreurs liées aux incertitudes dans les données d’entrée ainsi qu’aux incertitudes des méthodes utilisées. L’objectif de cette thèse et de caractériser l’incertitude associée à la production de MNS par photogrammétrie. Nous utilisons des modèles d’incertitude spécifiques, à savoir des probabilités imprécises, et plus particulièrement des distributions de possibilité, afin de caractériser l’incertitude résultant du traitement des images stéréo. Ces modèles définissent des “ensembles crédaux”, qui sont des ensembles convexes de distributions de probabilité. L’intérêt de ces ensembles crédaux est d’être mieux adaptés pour représenter l’incertitude résultant de connaissances incomplètes ou imparfaites, par rapport aux simples distributions de probabilité. En présence de plusieurs sources d’incertitudes, il est également nécessaire de considérer leurs relations de dépendance. Pour cela, il est courant d’utiliser des copules, qui sont des modèles représentant la dépendance entre plusieurs variables aléatoires. Dans cette thèse, trois méthodes distinctes sont introduites afin de joindre des ensembles crédaux marginaux en des ensembles crédaux multivariés à l’aide de copules. Les relations entre ces méthodes sont ensuite étudiées pour des copules spécifiques ainsi que pour différents modèles de probabilités imprécises. Une application de ces ensembles crédaux multivariés est ensuite proposée, afin de propager l’incertitude d’images stéréo dans un problème d’appariement. Différentes optimisations et façons de faciliter la propagation de l’incertitude sont présentées. La propagation correcte de l’incertitude est enfin validée à l’aide de méthodes de Monte-Carlo. Une seconde contribution de cette thèse concerne la modélisation de l’incertitude intrinsèque de l’algorithme d’appariement en utilisant des distributions de possibilité. Une méthode est proposée pour générer des intervalles de confiance associés aux résultats de l’étape d’appariement, et ces intervalles sont propagés jusqu’à la fin du pipeline stéréo, produisant ainsi des intervalles de confiance d’élévation pour les MNS. La taille et la précision de ces intervalles est évaluée en utilisant des images satellites réelles et des MNS pour lesquels une vérité terrain est disponible. Les intervalles ainsi créés contiennent correctement la vérité terrain au moins 90 % du tempsCurrently, Digital Surface Models (DSMs) are required in many applications, such as for managing water resources, monitoring biomass, evaluating damages caused by natural catastrophes, or for urban planning. DSMs can mainly be produced by Radar interferometry, photogrammetry or LiDAR scanning. In this context, CNES and Airbus are planning the launch of the CO3D constellation of satellites to massively provide highly accurate DSMs using photogrammetry. A performance map will also be provided alongside the DSM to characterize potential errors resulting from the uncertainty on input data or on its processing. The objective of this thesis is to characterize the uncertainty associated with the production of DSMs using photogrammetry. To do so, special uncertainty models, namelyimprecise probabilities, and more specifically possibility distributions, are employed to characterize the uncertainty arising from stereo images processing. Those models define credal sets, which are convex sets of probability distributions. Credal sets are well-suited to represent uncertainty resulting from incomplete or imperfect knowledge, which can be a limitation for a single probability distribution. In the presence of multiple sources of uncertainty, their dependency must also be considered. For this purpose, it is possible to consider copulas, which are models used to represent the dependency between multiple random variables. In this thesis, three different methods are introduced to join marginal credal sets into multivariate credal sets using copulas. The relationships between those methods are then investigated, for specific copulas and different models of imprecise probabilities. An application of those multivariate credal sets is then proposed, for propagating the uncertainty of stereo images in a dense stereo-matching problem. Different optimizations and ways to facilitate the uncertainty propagation are presented. The correct uncertainty propagation is validated using Monte Carlo sampling. A second contribution of this thesis concerns the uncertainty modeling of the dense matching algorithm itself using possibility distributions. A method is presented for generating confidence intervals associated with the results of the dense-matching step. Those intervals are then propagated to the end of the stereo pipeline, therefore producing elevation confidence intervals for the DSMs. The size and accuracy of intervals are then evaluated, using real satellites images and DSMs for which a ground truth is available. Elevation intervals correctly contain the ground truth at least 90% of the time
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Dessolin, Samuel. "Membrane models for a controllable surface". Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/17527.
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Miller, Matthew Lowell. "Analysis of Viewshed Accuracy with Variable Resolution LIDAR Digital Surface Models and Photogrammetrically-Derived Digital Elevation Models". Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/35692.
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The analysis of visibility between two points on the earthâ s terrain is a common use of GIS software. Most commercial GIS software packages include the ability to generate a viewshed, or a map of terrain surrounding a particular location that would be visible to an observer. Viewsheds are often generated using â bare-earthâ Digital Elevation Models (DEMs) derived from the process of photogrammetry. More detailed models, known as Digital Surface Models (DSMs), are often generated using Light Detection and Ranging (LIDAR) which uses an airborne laser to scan the terrain. In addition to having greater accuracy than photogrammetric DEMs, LIDAR DSMs include surface features such as buildings and trees.
This project used a visibility algorithm to predict visibility between observer and target locations using both photogrammetric DEMs and LIDAR DSMs of varying resolution. A field survey of the locations was conducted to determine the accuracy of the visibility predictions and to gauge the extent to which the presence of surface features in the DSMs affected the accuracy. The use of different resolution terrain models allowed for the analysis of the relationship between accuracy and optimal grid size. Additionally, a series of visibility predictions were made using Monte Carlo methods to add random error to the terrain elevation to estimate the probability of a targetâ s being visible. Finally, the LIDAR DSMs were used to determine the linear distance of terrain along the lines-of-sight between the observer and targets that were obscured by trees or bushes. A logistic regression was performed between that distance and the visibility of the target to determine the extent to which a greater amount of vegetation along the line-of-sight impacted the targetâ s visibility.Master of Science
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Aktaruzzaman, Md [Verfasser], i Theo G. [Akademischer Betreuer] Schmitt. "High Resolution Digital Surface Model (DSM) to Support Modelling of Urban Flooding / Md Aktaruzzaman. Betreuer: Theo G. Schmitt". Kaiserslautern : Universitätsbibliothek Kaiserslautern, 2012. http://d-nb.info/1018522344/34.
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Rodrigues, Avilmar Antonio. "Uso de veículos aéreos não tripulados para mapeamento e avaliação de erosão urbana". Universidade Federal de Goiás, 2016. http://repositorio.bc.ufg.br/tede/handle/tede/6646.
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This research aimed to evaluate the use of Unmanned Aerial Vehicle (UAV) as a platform for taking aerial photographs for mapping erosion planialtimetric located in urban areas. In addition, we evaluated the need to use or not to field control points for the generation of Digital Surface Model (DSM) and ortomosaico as tools to evaluate the erosive process. Despite the wide variation in attitude of aerial photographs that make up the aerophotogrammetric block arising from the instability of the UAV, it was possible to generate the MDS and ortomosaico with or without control points. This research was conducted in two urban erosions located in Goiania in Sector Fonte Nova in the stream of grass and the other in Silvânia called foot-washing. Whole generation of MDS, Digital Surface Model (MDT) and ortomosaico were performed in Agisoft PhotoScan program in semi-automatic processing, if used control points, or automatic without control points. The ortomosaicos generated without control points presented rotation, translation and scale of different generated with support. In addition, MDS generated without control points showed elevation or lowering of the reference surface with respect to the generated control, it is emphasized that these discrepancies are not constant. When performing automatic conversion of MDS to MDT, it was realized that the program was not able to eliminate the shrub vegetation located within the erosion. The vegetation or tree, shrub or undergrowth (grass) prevents proper limitation of erosion to the volume calculation. But unlike the MDS generated between two distinct epochs identifies the changes in the interval of time in areas without vegetation. The use of control points was essential to ensure the orientation, scale and the reference plane in the products generated from aerial photographs and thus evaluate the changes. Anyway, the UAV can be used as a platform for taking aerial photographs for generating cartographic products that enable the mapping and evaluation of erosions.
Esta pesquisa teve por objetivo avaliar a utilização do Veículo Aéreo Não Tripulado (VANT) como plataforma para a tomada de fotografias aéreas para o mapeamento planialtimétrico de erosão situada em zona urbana. Além disso, analisou-se a necessidade de utilização ou não de pontos de controle de campo para a geração de Modelo Digital de Superfície (MDS) e ortomosaico como instrumentos para examinar o processo erosivo. Apesar da grande variação da atitude da aeronave durante a obtenção das fotografias aéreas que compõem o bloco aerofotogramétrico, foi possível gerar o MDS e o ortomosaico com ou sem pontos de controle. Este estudo foi realizado em duas erosões urbanas, uma situada em Goiânia-GO, no Setor Fonte Nova/Córrego do Capim, e a outra em Silvânia-GO, denominada de Lava-Pés. Toda a geração dos MDS, Modelo Digital de Terreno (MDT) e ortomosaico foram realizados no programa Agisoft PhotoScan, em processamento semiautomático (i.e., com pontos de controle) e automático (i.e., sem pontos de controle). Os ortomosaicos gerados sem pontos de controle apresentaram rotação, translação e escala diferente dos gerados com apoio. Ademais, os MDS gerados sem pontos de controle apresentaram elevação ou rebaixamento da superfície de referência em relação aos gerados com controle. Ressalta-se, ainda, que essas discrepâncias não foram constantes. Ao realizar a conversão automática do MDS para o MDT, percebeu-se que o programa não foi capaz de eliminar a vegetação arbustiva localizada no interior da erosão. As vegetações arbórea, arbustiva ou rasteira (gramíneas) impedem a correta delimitação da erosão para o cálculo do volume. Porém, a diferença dos MDS gerados entre duas épocas distintas propicia identificar as alterações ocorridas nesse intervalo de tempo nas regiões sem cobertura vegetal. O uso de pontos de controle foi essencial para garantir a orientação, a escala e o plano de referência nos produtos gerados a partir das fotografias aéreas e, assim, avaliar as modificações da erosão. Por fim, o VANT pode ser utilizado como plataforma para a tomada de fotografias aéreas para gerar produtos cartográficos que possibilitem o mapeamento e as avaliações das erosões, sobretudo em áreas urbanas.
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Roecker, Stephen M. "Solving for y| digital soil mapping using statistical models and improved models of land surface geometry". Thesis, West Virginia University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1524652.
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Digital soil mapping (DSM) is a rapidly growing area of soil research that has great potential for enhancing soil survey activities and advancing knowledge of soil-landscape relationships. To date many successful studies have shown that geographic datasets can be used to model soil spatial variation. This thesis addresses two issues relevant to DSM, scale effects on digital elevation models, and predicting soil properties. The first issue examined was the effect of spatial extent on the calculation of geometric land surface parameters (LSP) (e.g. slope gradient). This is a significant issue as they represent some of the most common predictors used in DSM. To examine this issue two case studies were designed. The first evaluated the systematic effects of varying both grid and neighborhood size on LSP, while the second examined how the correlation between soil and LSP vary with grid and neighborhood size. Results of the first case study demonstrate that finer grid sizes were more sensitive to the scale of LSP calculation than larger grid sizes. While the magnitude of effect was diminished when comparing a high relief landscape to a low relief landscape, the shape and location of the effect was similar. Results of the second case study showed that the correlation between soil properties and slope curvatures were similarly optimized when varying the spatial extent, but that the effect was more sensitive to grid size than neighborhood size. Slope gradient also showed significant correlations with some of the soil properties, but was not sensitive to changes in grid or neighborhood size.
The second study attempted to predict numerous physical and chemical soil properties for several depth intervals (0-15, 15-60, 60-100, and 100-150-centimeters), using generalized linear models (GLM) and geographic datasets. The area examined was the Upper Gauley Watershed on the Monongahela National Forest, which covers approximately 82,500 acres (33,400 hectares). This watershed represents a complex landscape with contrasting geologic strata, deciduous and coniferous forests, and steep slopes. Given this landscape diversity it was still possible to fit GLM which explained on average 38 percent of the adjusted deviance for rock fragment content, and exchangeable calcium and magnesium, and phosphorus. Some of the most commonly selected environmental predictors were slope curvatures, lithology types, and relative slope position indices. This seems to validate the prominence of these variables in theoretical soil-landscape models. Had the correlation between the soil properties and slope curvatures not been optimized by varying the spatial extent, it is likely that another less suitable LSP would have been selected.
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Jaafar, Jasmee. "An evaluation of the generation and potential applications of digital surface models". Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326567.
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Mtshatsha, Bandile. "Analysis of photogrammetrically-derived digital surface and terrain models for building recognition". Master's thesis, University of Cape Town, 1997. http://hdl.handle.net/11427/9466.
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Bibliography: leaves 79-83.Buildings are one of the most frequently occurring man-made objects and in urban scenes their detection and reconstruction, e.g., in the form of three-dimensional CAD (computer aided design) models, is very important to many users such as architects, town planners and telecommunications and environmental engineers. This thesis examines the role of digital terrain and surface models in supporting this reconstruction process. The thesis is structured into four main parts, namely, image matching to derive the data sets, building detection to delineate buildings from other man-made objects in DSM (digital surface model), DSM quality analysis to determine the reliability of the data, hydrological analysis to determine flood zones as an additional example of DTM application and finally conclusions and possible future outlook. Image matching was performed using an in-house image matching software in the Geomatics department. Off-the-shelf GIS functionality was used to tackle building detection, DSM quality analysis and hydrological analysis. A key feature of GIS functionality is the ability to exploit standard functions for the input/output, management, spatial analysis, editing and visualisation. It also aims at enhancing the accessibility of developed tools to end users.
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Larsson, Johan, i Marcus Stark. "Utvärdering av lägesosäkerheter i ortofoton framtagna med hjälp av DJI Phantom 4 RTK". Thesis, Högskolan i Gävle, Samhällsbyggnad, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-29914.
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Flygfotografering med Unmanned Aircraft System (UAS) är i jämförelse med traditionell fotogrammetri effektivare, billigare och säkrare vilket har medfört att denna teknik föredras av många aktörer. Ett tidskrävande arbete som varit svårt att kringgå är att etablera flygsignaler på marken som används för att georeferera och kontrollera flygbilderna med. Under 2018 presenterade UAS-tillverkaren DJI sin nya quadcopter med integrerad Real-Time Kinematic (RTK)-modul. I samband med detta kan kontinuerliga och noggranna positioner levereras via Nätverks-RTK (NRTK) och behovet av markstödpunkter reduceras. I denna studie undersöktes lägesosäkerheterna i plan för ortofoton som framställdes med hjälp av en DJI Phantom 4 RTK där flygbilderna georefererades med begränsat antal eller utan markstödpunkter. Lägesosäkerheterna beräknades och kontrollerades enligt Handbok i mät- och kartfrågor (HMK) – Ortofoto, vilket är ett stöddokument inom ämnet. Vid framställning av ett ortofoto krävs även en digital terrängmodell (DTM) eller en digital ytmodell (Digital Surface Model, DSM) och kvaliteten av denna har stor inverkan på ortofotots kvalitet. I denna studie kontrollerades och utvärderades därför en del av den DSM som användes vid ortofotoframställning för respektive uppsättning enligt den tekniska specifikationen SIS-TS 21144:2016. Resultatet från studien visar att ett ortofoto går att framställas utan markstödpunkter och samtidigt klara kraven på specificerad lägesosäkerhet enligt HMK-standardnivå 3. Den sammanlagda lägesosäkerheten beräknades till 0,029 m vilket är 5 mm högre i jämförelse med ett ortofoto som baserats på traditionell georefereringsmetod, dvs. med markstödpunkter. Kravet på kvalitet i höjddata uppfylldes också för ortofotoframställning trots att en systematisk effekt i höjd uppkom. Denna effekt påverkade inte ortofotots koordinater i plan då standardosäkerheterna i höjd var låga. Resultatet visade att om två markstödpunkter adderades i vardera änden av området, kunde de systematiska effekterna i höjd minimeras och det var då möjligt att skapa en DSM som uppfyller kraven för detaljprojektering (noggrannhetsklass 1–3) enligt SIS-TS 21144:2016.Aerial photography with UAS is in comparison with traditional photogrammetry more efficient, cheaper and safer which has led to this technology being preferred by many performers. A time-consuming job that has been difficult to avoid is to establish signals at the ground that are used for georeferencing and evaluate the results. In 2018, the UAS manufacturer DJI presented its new quadcopter with integrated Real-Time Kinematic (RTK) module. This allows continuous and accurate positions delivered via Network RTK (NRTK) and the need of ground control points can be reduced. In this study, investigations of the position uncertainties in orthophotos produced using a DJI Phantom 4 RTK carried out where the aerial images were georeferenced with limited numbers or without ground control points. The position uncertainties were calculated and controlled according to the Swedish HMK – Ortofoto (Orthophoto) which is a document within the subject. When producing an orthophoto, a digital terrain model (DTM) or a digital surface model (DSM) is also required and the quality of this has a great impact on the result. Therefore, a part of the DSM used for orthophoto production for each set was checked and evaluated according to the Swedish technical specification, SIS-TS 21144:2016. The result of the study shows that an orthophoto can be produced without ground control points and at the same time meet the requirements for specified position uncertainty according to HMK standard level 3. The total position uncertainty was calculated to be 0,029 m, which is 5 mm higher compared to the orthophoto based on the traditional georeferencing method, i.e. with ground control points. The requirement for quality in height data was also met for orthophoto production even though a systematic effect in height occurred. This effect did not affect the plane coordinates in the orthophoto because of the low standard uncertainties in height. The result showed that if two ground control points were added at each end of the area, the systematic effects were minimized, and it was possible to produce a DSM that fulfils the requirements for accuracy class 1-3 according to SIS-TS 21144:2016.
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Wahl, Roland [Verfasser]. "Scalable Realtime Rendering and Interaction with Digital Surface Models of Landscapes and Cities / Roland Wahl". Bonn : Universitäts- und Landesbibliothek Bonn, 2016. http://d-nb.info/1119888530/34.
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Kamaruddin, Mohammad Halmi. "The potential of interferometric synthetic aperture radar digital surface models for mapping forest vertical structure". Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416309.
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Wang, Jianjun. "Modelling surface solar energy by use of landsat thematic mapper data and digital elevation models". Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336667.
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ROMANENGO, CHIARA. "Recognition and representation of curve and surface primitives in digital models via the Hough transform". Doctoral thesis, Università degli studi di Genova, 2023. https://hdl.handle.net/11567/1103813.
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Curve and surface primitives have an important role in conveying an object shape and their recognition finds significant applications in manufacturing, art, design and medical applications. When 3D models are acquired by scanning real objects, the resulting geometry does not explicitly encode these curves and surfaces, especially in the presence of noise or missing data. Then, the knowledge of the parts that compose a 3D model allows the reconstruction of the model itself. The problem of recognising curves and surfaces and providing a mathematical representation of them can be addressed using the Hough transform technique (HT), which in literature is mainly used to recognise curves in the plane and planes in space. Only in the last few years, it has been explored for the fitting of space curves and extended to different families of surfaces. Such a technique is robust to noise, does not suffer from missing parts and benefits from the flexibility of the template curve or surface.
For these reasons, our approach is inspired by a generalisation of the Hough transform defined for algebraic curves.
In this thesis, we present the methods we implemented and the results we obtained about the recognition, extraction, and representation of feature parts that compose a 3D model (both meshes and point clouds). Specifically, we first study the recognition of plane curves, simple and compound, expressed both in implicit and parametric form, with a focus on the application of cultural heritage and geometric motifs. Then, we analyse the extension of the method to space curves, concentrating on the improvement of the model through the insertion of the recognised curves directly on its surface.
To overcome the limitation of knowing in advance the family of curves to be used with the HT,
we introduce a piece-wise curve approximation using specific parametric, low-degree polynomial curves.
Finally, we analyse how to recognise simple and complex geometric surface primitives on both pre-segmented and entire point clouds, and we show a comparison with state-of-the-art approaches on two benchmarks specifically created to evaluate existing and our methods.
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Li, Peng. "A vehicle-based laser system for generating high-resolution digital elevation models". Diss., Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/3890.
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McClean, Colin John. "The scale-free and scale-bound properties of land surfaces : fractal analysis and specific geomorphometry from digital terrain models". Thesis, Durham University, 1990. http://etheses.dur.ac.uk/5999/.
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The scale-bound view of landsurfaces, being an assemblage of certain landforms, occurring within limited scale ranges, has been challenged by the scale-free characteristics of fractal geometry. This thesis assesses the fractal model by examining the irregularity of landsurface form, for the self-affine behaviour present in fractional Brownian surfaces. Different methods for detecting self-affine behaviour in surfaces are considered and of these the variogram technique is shown to be the most effective. It produces the best results of two methods tested on simulated surfaces, with known fractal properties. The algorithm used has been adapted to consider log (altitude variance) over a sample of log (distances) for: complete surfaces; subareas within surfaces; separate directions within surfaces. Twenty seven digital elevation models of landsurfaces arc re-examined for self- affine behaviour. The variogram results for complete surfaces show that none of these are self-affine over the scale range considered. This is because of dominant slope lengths and regular valley, spacing within areas. For similar reasons subarea analysis produces the non-fractal behaviour of markedly different variograms for separate subareas. The linearity of landforms in many areas, is detected by the variograms for separate directions. This indicates that the roughness of landsurfaces is anisotropic, unlike that of fractal surfaces. Because of difficulties in extracting particular landforms from their landsurfaces, no clear links between fractal behaviour, and landform size distribution could be established. A comparative study shows the geomorphometric parameters of fractal surfaces to vary with fractal dimension, while the geomorphometry of landsurfaces varies with the landforms present. Fractal dimensions estimated from landsurfaces do not correlate with geomorphometric parameters. From the results of this study, real landsurfaces would not appear to be scale- free. Therefore, a scale-bound approach towards landsurfaces would seem to be more appropriate to geomorphology than the fractal alternative.
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Reynolds, James Robb. "Using digital elevation models to measure the surface and volumetric change of Athabasca Glacier, Canada, 1919-1979". Waterloo, Ontario : Wilfrid Laurier University, 1996. http://wwwlib.umi.com/cr/wlu/fullcit?pMM11455.
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Thesis (M.A.)-Wilfrid Laurier University, 1996.Includes bibliographical references (l.174-182). Issued also online via the World Wide Web; files in PDF format available to WLU users. Available in microfiche format.
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Aasen, Helge Verfasser], i Georg [Gutachter] [Bareth. "The acquisition of Hyperspectral Digital Surface Models of crops from UAV snapshot cameras / Helge Aasen ; Gutachter: Georg Bareth". Köln : Universitäts- und Stadtbibliothek Köln, 2016. http://d-nb.info/1115330632/34.
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Aasen, Helge [Verfasser], i Georg [Gutachter] Bareth. "The acquisition of Hyperspectral Digital Surface Models of crops from UAV snapshot cameras / Helge Aasen ; Gutachter: Georg Bareth". Köln : Universitäts- und Stadtbibliothek Köln, 2016. http://d-nb.info/1115330632/34.
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Sadeq, Haval AbdulJabbar. "Merging digital surface models sourced from multi-satellite imagery and their consequent application in automating 3D building modelling". Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6861/.
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Recently, especially within the last two decades, the demand for DSMs (Digital Surface Models) and 3D city models has increased dramatically. This has arisen due to the emergence of new applications beyond construction or analysis and consequently to a focus on accuracy and the cost. This thesis addresses two linked subjects: first improving the quality of the DSM by merging different source DSMs using a Bayesian approach; and second, extracting building footprints using approaches, including Bayesian approaches, and producing 3D models. Regarding the first topic, a probabilistic model has been generated based on the Bayesian approach in order to merge different source DSMs from different sensors. The Bayesian approach is specified to be ideal in the case when the data is limited and this can consequently be compensated by introducing the a priori. The implemented prior is based on the hypothesis that the building roof outlines are specified to be smooth, for that reason local entropy has been implemented in order to infer the a priori data. In addition to the a priori estimation, the quality of the DSMs is obtained by using field checkpoints from differential GNSS. The validation results have shown that the model was successfully able to improve the quality of the DSMs and improving some characteristics such as the roof surfaces, which consequently led to better representations. In addition to that, the developed model has been compared with the Maximum Likelihood model which showed similar quantitative statistical results and better qualitative results. Perhaps it is worth mentioning that, although the DSMs used in the merging have been produced using satellite images, the model can be applied on any type of DSM. The second topic is building footprint extraction based on using satellite imagery. An efficient flow-line for automatic building footprint extraction and 3D model construction, from both stereo panchromatic and multispectral satellite imagery was developed. This flow-line has been applied in an area of different building types, with both hipped and sloped roofs. The flow line consisted of multi stages. First, data preparation, digital orthoimagery and DSMs are created from WorldView-1. Pleiades imagery is used to create a vegetation mask. The orthoimagery then undergoes binary classification into ‘foreground’ (including buildings, shadows, open-water, roads and trees) and ‘background’ (including grass, bare soil, and clay). From the foreground class, shadows and open water are removed after creating a shadow mask by thresholding the same orthoimagery. Likewise roads have been removed, for the time being, after interactively creating a mask using the orthoimagery. NDVI processing of the Pleiades imagery has been used to create a mask for removing the trees. An ‘edge map’ is produced using Canny edge detection to define the exact building boundary outlines, from enhanced orthoimagery. A normalised digital surface model (nDSM) is produced from the original DSM using smoothing and subtracting techniques. Second, start Building Detection and Extraction. Buildings can be detected, in part, in the nDSM as isolated relatively elevated ‘blobs’. These nDSM ‘blobs’ are uniquely labelled to identify rudimentary buildings. Each ‘blob’ is paired with its corresponding ‘foreground’ area from the orthoimagery. Each ‘foreground’ area is used as an initial building boundary, which is then vectorised and simplified. Some unnecessary details in the ‘edge map’, particularly on the roofs of the buildings can be removed using mathematical morphology. Some building edges are not detected in the ‘edge map’ due to low contrast in some parts of the orthoimagery. The ‘edge map’ is subsequently further improved also using mathematical morphology, leading to the ‘modified edge map’. Finally, A Bayesian approach is used to find the most probable coordinates of the building footprints, based on the ‘modified edge map’. The proposal that is made for the footprint a priori data is based on the creating a PDF which assumes that the probable footprint angle at the corner is 90o and along the edge is 180o, with a less probable value given to the other angles such as 45o and 135o. The 3D model is constructed by extracting the elevation of the buildings from the DSM and combining it with the regularized building boundary. Validation, both quantitatively and qualitatively has shown that the developed process and associated algorithms have successfully been able to extract building footprints and create 3D models.
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Feldmann, Dirk [Verfasser], i Klaus H. [Akademischer Betreuer] Hinrichs. "Real-time rendering and synthesis of digital surface models using textures of time-varying extension / Dirk Feldmann ; Betreuer: Klaus H. Hinrichs". Münster : Universitäts- und Landesbibliothek Münster, 2013. http://d-nb.info/1141383578/34.
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Lima, Silva Sonia Maria [Verfasser], i Volker [Akademischer Betreuer] Hochschild. "Semi-automatic identification of neogenic deposits by using high resolution digital surface models in Southeastern Brazil / Sonia Maria Lima Silva ; Betreuer: Volker Hochschild". Tübingen : Universitätsbibliothek Tübingen, 2015. http://d-nb.info/1197057080/34.
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Avbelj, Janja [Verfasser], Richard H. G. [Akademischer Betreuer] Bamler, Peter [Akademischer Betreuer] Reinartz i Markus [Akademischer Betreuer] Gerke. "Fusion of Hyperspectral Images and Digital Surface Models for Urban Object Extraction / Janja Avbelj. Betreuer: Richard H. G. Bamler. Gutachter: Peter Reinartz ; Markus Gerke ; Richard H. G. Bamler". München : Universitätsbibliothek der TU München, 2015. http://d-nb.info/1098428730/34.
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Bartie, Philip James. "Advances in Visibility Modelling in Urban Environments to Support Location Based Services". Thesis, University of Canterbury. Geography, 2011. http://hdl.handle.net/10092/5655.
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People describe and explore space with a strong emphasis on the visual senses, yet modelling the field of view has received little attention within the realm of Location Based Services (LBS), in part due to the lack of useful data. Advances in data capture, such as Light Detection and Ranging (LiDAR), provide new opportunities to build digital city models and expand the range of applications which use visibility analysis. This thesis capitalises on these advances with the development of a visibility model to support a number of innovative LBS functions in an urban region and particular focus is given to the visibility model‟s supporting role in the formation of referring expressions, the descriptive phrases used to identify objects in a scene, which are relevant when delivering spatial information to the user through a speech based interface. Speech interfaces are particularly useful to mobile users with restricted screen viewing opportunities, such as navigational support for motorists and a wider range of tasks including delivering information to urban pedestrians. As speech recognition accuracies improve so new interaction opportunities will allow users to relate to their surroundings and retrieve information on buildings in view through spoken descriptions. The papers presented in this thesis work towards this goal, by translating spatial information into a form which matches the user‟s perspective and can be delivered over a speech interface. The foundation is the development of a new visual exposure model for use in urban areas, able to calculate a number of metrics about Features of Interest (FOIs), including the façade area visible and the percentage on the skyline. The impact of urban vegetation as a semi-permeable visual barrier is also considered, and how visual exposure calculations may be adjusted to accommodate under canopy and through canopy views. The model may be used by pedestrian LBSs, or applied to vehicle navigation tasks to determine how much of a route ahead is in view for a car driver, identifying the sections with limited visibility or the best places for an overtaking manoeuvre. Delivering information via a speech interface requires FOI positions to be defined according to projective space relating to the user‟s viewpoint, rather than topological or metric space, and this is handled using a new egocentric model. Finally descriptions of the FOIs are considered, including a method to automatically collect façade colours by excluding foreground objects, and a model to determine the most appropriate description to direct the LBS user‟s attention to a FOI in view.
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Gallitelli, Donato. "Traitements de surface mécaniques : modélisation et caractérisations expérimentales". Thesis, Troyes, 2018. http://www.theses.fr/2018TROY0013.
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Les traitements de surface occupent une place très importante au niveau industriel, visant à améliorer les propriétés mécaniques des matériaux. Parmi eux, le grenaillage de précontrainte (GC) est certainement le plus renommé, même si le grenaillage ultrasonore (GUS) et le choc laser (LSP) sont de plus en plus présents. Ce travail consiste en une étude approfondie du grenaillage qui peut être divisée en trois parties. La première partie propose un modèle semi analytique pour la prédiction des contraintes résiduelles après grenaillage conventionnel ou ultrasonore. Une démarche permettant d’obtenir la déformation d’une pièce à géométrie complexe à partir des paramètres du procède de grenaillage conventionnel ou ultrasonore a été mise en place. Plusieurs simulations numériques d’impacts bille-massif ont été réalisées dans l’objectif de choisir les variables à prendre en compte dans le modèle proposé. Dans une deuxième partie, plusieurs séries de mesures expérimentales et de simulations numériques de la dynamique des billes ont été réalisées afin de permettre une optimisation et une meilleure compréhension du GUS. Dans la dernière partie de ce travail, un grand nombre de mesures expérimentales ont été menées afin d’étudier le couplage entre le grenaillage ultrasonore et la nitruration gazeuse d’un acier martensitique. Enfin, une comparaison entre le grenaillage ultrasonore, conventionnel et le choc laser est proposéeMechanical surface treatments are widely used in manufacturing industries in order to improve mechanical properties of materials. Among them, shot peening is certainly the most known, even if ultrasonic shot peening and laser shock peening are becoming more and more common. This work consists in a large study of shot peening, divided in three parts.The first one is focused on the conception of a semi analytical model for residual stress prediction after conventional shot peening or ultrasonic shot peening. An approach able to chain the whole shot peening process, starting from process parameters to residual stress field in a structure is proposed. Several numerical simulations of shot-body impacts are carried out in order to determine the parameters of the model.In the second part of this work, a characterization of the ultrasonic shot peening process is performed thanks to many experimental measurements and shot dynamic simulations.The last part of this PhD work corresponds to an experimental analysis focused on the combination of ultrasonic shot peeing with gas nitriding on a martensitic steel. A comparison between ultrasonic shot peening, conventional shot peeing and laser shock peening effects is finally proposed
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Puech, Christian. "Détermination des états de surface par télédétection pour caractériser les écoulements des petits bassins versants : application à des bassins en zone méditerranéenne et en zone tropicale sèche". Grenoble 1, 1993. http://www.theses.fr/1993GRE10175.
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La liaison entre la teledetection des etats de surface et l'hydrologie est etudiee sur deux sites, revelant l'importance des problemes d'echelle et la necessite d'informations hydrologiques de type versant. Sur les bassins du real collobrier (var, france) apres des corrections imposees par le fort relief, le traitement de l'imagerie satellitaire conduit a une cartographie des essences forestieres. La part d'ecoulement relative a chaque zone homogene est calculee a des pas de temps annuel, trimestriel, mensuel et sur des episodes. Une liaison coherente entre zones et types d'ecoulement est obtenue mais la signification exacte de zone homogene, et le manque d'observations hydrologiques de versant rendent la validation delicate. Sur des bassins saheliens, un traitement d'image specifique a des zones heterogenes est mis au point, base sur une detection en deux niveaux: paysage, puis etats de surface type du sahel. Le ruissellement elementaire correspondant est agrege sur le bassin versant selon le modele lineaire de l'orstom. Certaines zones non contributives en grand rendent indispensable une approche complementaire a un autre niveau d'echelle
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Zelasco, José Francisco. "Gestion des données : contrôle de qualité des modèles numériques des bases de données géographiques". Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20232.
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Les modèles numériques de terrain, cas particulier de modèles numériques de surfaces, n'ont pas la même erreur quadratique moyenne en planimétrie qu'en altimétrie. Différentes solutions ont été envisagées pour déterminer séparément l'erreur en altimétrie et l'erreur planimétrique, disposant, bien entendu, d'un modèle numérique plus précis comme référence. La démarche envisagée consiste à déterminer les paramètres des ellipsoïdes d'erreur, centrées dans la surface de référence. Dans un premier temps, l'étude a été limitée aux profils de référence avec l'ellipse d'erreur correspondante. Les paramètres de cette ellipse sont déterminés à partir des distances qui séparent les tangentes à l'ellipse du centre de cette même ellipse. Remarquons que cette distance est la moyenne quadratique des distances qui séparent le profil de référence des points du modèle numérique à évaluer, c'est à dire la racine de la variance marginale dans la direction normale à la tangente. Nous généralisons à l'ellipsoïde de révolution. C'est le cas ou l'erreur planimétrique est la même dans toutes les directions du plan horizontal (ce n'est pas le cas des MNT obtenus, par exemple, par interférométrie radar). Dans ce cas nous montrons que le problème de simulation se réduit à l'ellipse génératrice et la pente du profil correspondant à la droite de pente maximale du plan appartenant à la surface de référence. Finalement, pour évaluer les trois paramètres d'un ellipsoïde, cas où les erreurs dans les directions des trois axes sont différentes (MNT obtenus par Interférométrie SAR), la quantité des points nécessaires pour la simulation doit être importante et la surface tr ès accidentée. Le cas échéant, il est difficile d'estimer les erreurs en x et en y. Néanmoins, nous avons remarqué, qu'il s'agisse de l'ellipsoïde de révolution ou non, que dans tous les cas, l'estimation de l'erreur en z (altimétrie) donne des résultats tout à fait satisfaisantsA Digital Surface Model (DSM) is a numerical surface model which is formed by a set of points, arranged as a grid, to study some physical surface, Digital Elevation Models (DEM), or other possible applications, such as a face, or some anatomical organ, etc. The study of the precision of these models, which is of particular interest for DEMs, has been the object of several studies in the last decades. The measurement of the precision of a DSM model, in relation to another model of the same physical surface, consists in estimating the expectancy of the squares of differences between pairs of points, called homologous points, one in each model which corresponds to the same feature of the physical surface. But these pairs are not easily discernable, the grids may not be coincident, and the differences between the homologous points, corresponding to benchmarks in the physical surface, might be subject to special conditions such as more careful measurements than on ordinary points, which imply a different precision. The generally used procedure to avoid these inconveniences has been to use the squares of vertical distances between the models, which only address the vertical component of the error, thus giving a biased estimate when the surface is not horizontal. The Perpendicular Distance Evaluation Method (PDEM) which avoids this bias, provides estimates for vertical and horizontal components of errors, and is thus a useful tool for detection of discrepancies in Digital Surface Models (DSM) like DEMs. The solution includes a special reference to the simplification which arises when the error does not vary in all horizontal directions. The PDEM is also assessed with DEM's obtained by means of the Interferometry SAR Technique
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Le, Meillour Françoise. "Etude expérimentale et numérique de la contribution des eaux de surface et de subsurface à la formation des crues : conséquences sur l'hydrogramme d'un bassin versant (application au Real Collobrier)". Phd thesis, Université Joseph Fourier (Grenoble), 1996. http://tel.archives-ouvertes.fr/tel-00694046.
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L'objectif de ce travail est une conlribution à l'analyse des processus de formation des crues sur un bassin méditerranéen à l'occasion des épisodes pluvieux. Nous avons essayé de comprendre les caractéristiques hydrologiques d'un bassin par une démarche mécaniste. Pour cela, nous avons étudié la part, dans le débit de la rivière pendant les crues, du débit provenant d'un écou!ement soit par ruissellement généralisé, soit souterrain ou de subsurface, soit sur zones saturées contributives. Le bassin versant a été schématisé comme la succession de deux unités hydrologiques: le versant et le réseau hydrographique. Ainsi, la première partie de ce mémoire est consacrée à l'analyse mécaniste des apports à la riuvière à l'échelle du versant. Pour chaque processus, une étude expérimentale a été menée afin d'étudier les lois qui régissent ces écoulement. Nous avons montré. que les écoulements en surface ne suivent pas une loi d'écoulement plan turbulent Les écoulements en litière, immédiatement sous la surface du sol, suivent une loi de Manning. Enfin, les écoulements de subsurface suivent une lol de Darcy. A l'échelle du versant, la modélisation des écoulements avec les lois mesurées ne les entretient jamais assez longtemps pour expliquer les hydrogrammes de bassin. La seconde partie de ce mémoire consiste en une modélisation à l'échelle du bassin des écoulements dans le cas des trois processus de formation des crues. Cette modélisation a cherché à reproduire les hydrogrammes du bassin. On montre que lorsque le bassin est sec, les écoulements proviennent principalement du ruissellement généralisé. Lorsque le bassin est plus humide, les pluies mettent d'abord en activité des écoulements souterrains et de subsurface, puis si les pluies sont importantes, le mécanisme d'écoulement sur surfaces saturées contributives devient prépondérant
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Pedersen, Helle Anette. "Étude de la diffraction tridimensionnelle des ondes sismiques dans des structures à géométrie bidimensionnelle : développement théorique et applications". Grenoble 1, 1994. http://www.theses.fr/1994GRE10212.
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La diffraction tridimensionnelle (3d) des ondes sismiques par des structures a geometrie bidimensionnelle (2d) est etudiee par la methode indirecte d'elements de frontiere (ibem, pour indirect boundary element method). Les ondes incidentes peuvent arriver en dehors du plan 2d et, en consequence, la diffraction est 3d avec couplage de tous les types d'onde. Ce travail est divise en trois parties. La theorie de ibem et son extension aux problemes de diffraction 3d par des structures 2d sont presentees dans la premiere partie. La deuxieme est consacree a l'application de la methode pour l'etude de la diffraction et de l'amplification par des reliefs topographiques et des vallees sedimentaires. La derniere partie consiste en l'etude d'une suture lithospherique et en une simulation numerique de la diffraction des ondes de surface par cette suture. Les resultats majeurs de ce travail sont a la fois de nature theorique et pratique. Ibem s'avere etre une methode precise et rapide pour simuler la diffraction 3d par des structures 2d. Elle est numeriquement stable et permet le calcul du champ d'onde complet en prenant en compte le transfert d'energie entre differentes types d'ondes. Ibem semble ainsi etre un outil prometteur pour l'interpretation de donnees sismologiques. L'analyse de donnees ainsi que les simulations numeriques de la propagation d'ondes au travers de reliefs topographiques et de vallees sedimentaires montrent que: 1) les effets 3d sont importants, 2) l'amplification due aux reliefs topographiques est faible, et 3) des ondes diffractees sont emises du sommet des reliefs. Enfin, nous avons mis en evidence un changement rapide de la structure lithospherique sous la zone sorgenfrei-tornquist par analyse d'ondes de rayleigh de longue periode. La simulation numerique montre que les ondes de rayleigh incidentes sur une telle suture sont transmises ou reflechies sous la forme d'ondes de surface ou de volume
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Tanays, Eric. "Approche algorithmique des conceptions geometriques et geotechniques de mines a ciel ouvert : application a la mine de carmaux (u.e. tarn, h.b.c.m., cdf)". Paris, ENMP, 1989. http://www.theses.fr/1989ENMP0142.
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Le travail de recherche a pour objectif la realisation du logiciel degres destine a la prevision de la geometrie de la fosse d'une mine a ciel ouvert et la detection des risques de rupture. Il a ete mis en oeuvre sur le site de la "grande decouverte" de carmaux (tarn - france)
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CAPALDO, PAOLA. "High resolution radargrammetry with COSMO-SkyMed, TerraSAR-X and RADARSAT-2 imagery: development and implementation of an image orientation model for Digital Surface Model generation". Doctoral thesis, 2013. http://hdl.handle.net/11573/918553.
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Digital Surface and Terrain Models (DSM/DTM) have large relevance in several territorial applications, such as topographic mapping, monitoring engineering, geology, security, land planning and management of Earth's resources. The satellite remote sensing data offer the opportunity to have continuous observation of Earth's surface for territorial application, with short acquisition and revisit times. Meeting these requirements, the SAR (Synthetic Aperture Radar) high resolution satellite imagery could offer night-and-day and all-weather functionality (clouds, haze and rain penetration). Two different methods may be used in order to generate DSMs from SAR data: the interferometric and the radargrammetric approaches. The radargrammetry uses only the intensity information of the SAR images and reconstructs the 3D information starting from a couple of images similarly to photogrammetry. Radargrammetric DSM extraction procedure consists of two basic steps: the stereo pair orientation and the image matching for the automatic detection of homologous points.
The goal of this work is the definition and the implementation of a geometric model in order to orientate SAR imagery in zero Doppler geometry.
The radargrammetric model implemented in SISAR (Software per Immagini Satellitari ad Alta Risoluzione - developed at the Geodesy and Geomatic Division - University of Rome "La Sapienza") is based on the equation of radar target acquisition and zero Doppler focalization
Moreover a tool for the SAR Rational Polynomial Coefficients (RPCs) generation has been implemented in SISAR software, similarly to the one already developed for the optical sensors. The possibility to generate SAR RPCs starting from a radargrammetric model sounds of particular interest since, at present, the most part of SAR imagery is not supplied with RPCs, although the RPFs model is available in several commercial software. Only RADARSAT-2 data are supplied with vendors RPCs.
To test the effectiveness of the implemented RPCs generation tool and the SISAR radargrammetric orientation model the reference results were computed: the stereo pairs were orientated with the two model.
The tests were carried out on several test site using COSMO-SkyMed, TerraSAR-X and RADARSAT-2 data.
Moreover, to evaluate the advantages and the different accuracy between the orientation models computed without GCPs and the orientation model with GCPs a Monte Carlo test was computed.
At last, to define the real effectiveness of radargrammetric technique for DSM extraction and to compare the radrgrammetric tool implemented in a commercial software PCI-Geomatica v. 2012 and SISAR software, the images acquired on Beauport test site were used for DSM extraction. It is important underline that several test were computed. Part of this tests were carried out under the supervision of Prof. Thierry Toutin at CCRS (Canada Centre of Remote Sensing) where the PCI-Geomatica orientation model was developed, in order to check the better parameters solution to extract radargrammetric DSMs.
In conclusion, the results obtained are representative of the geometric potentialities of SAR stereo pairs as regards 3D surface reconstruction.
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Villa, C., Jo Buckberry i N. Lynnerup. "Evaluating osteological ageing from digital data". 2016. http://hdl.handle.net/10454/8762.
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YesAge at death estimation of human skeletal remains is one of the key issues in constructing a biological profile both in forensic and archaeological contexts. The traditional adult osteological methods evaluate macroscopically the morphological changes that occur with increasing age of specific skeletal indicators, such as the cranial sutures, the pubic bone, the auricular surface of the ilium and the sternal end of the ribs. Technologies such as CT and laser scanning are becoming more widely used in anthropology, and several new methods have been developed. This review focuses on how the osteological age-related changes have been evaluated in digital data. Firstly, the 3D virtual copies of the bones have been used to mimic the appearance of the dry bones and the application of the traditional methods. Secondly, the information directly extrapolated from CT scan has been used to qualitatively or quantitatively assess the changes of the trabecular bones, the thickness of the cortical bones, and to perform morphometric analyses. Lastly, the most innovative approach has been the mathematical quantification of the changes of the pelvic joints, calculating the complexity of the surface. The importance of new updated reference datasets, created thanks to the use of CT scanning in forensic settings, is also discussed.
CV was supported from the Danish Council for Independent Research (DFF – 4005-00102B – FTP)
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Krasowski, Christopher B. "On the modelling of solar radiation in urban environments – applications of geomatics and climatology towards climate action in Victoria". Thesis, 2019. http://hdl.handle.net/1828/11217.
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Modelling solar radiation data at a high spatiotemporal resolution for an urban environment can inform many different applications related to climate action, such as urban agriculture, forest, building, and renewable energy studies. However, the complexity of urban form, vastness of city-wide coverage, and general dearth of climatological information pose unique challenges doing so. To address some climate action goals related to reducing building emissions in the City of Victoria, British Columbia, Canada, applied geomatics and climatology were used to model solar radiation data suitable for informing renewable energy feasibility studies, including photovoltaic system sizing, costing, carbon offsets, and financial payback.
The research presents a comprehensive review of solar radiation attenuates, as well as methods of accounting for them, specifically in urban environments. A novel methodology is derived from the review and integrates existing models, data, and tools – those typically available to a local government. Using Light Detection and Ranging (LiDAR), a solar climatology, Esri’s ArcGIS Solar Analyst tool, and Python scripting, daily insolation (kWh/m2) maps are produced for the city of Victoria.
Particular attention is paid to the derivation of daily diffuse fraction from atmospheric clearness indices, as well as LiDAR classification and generation of a Digital Surface Model (DSM). Novel and significant improvements in computation time are realized through parallel processing. Model results exhibit strong correlation with empirical data and support the use of Solar Analyst for urban solar assessments when great care is taken to accurately and consistently represent model inputs and outputs integrated in a methodological approach.Graduate
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Bittner, Ksenia. "Building Information Extraction and Refinement from VHR Satellite Imagery using Deep Learning Techniques". Doctoral thesis, 2020. https://repositorium.ub.uni-osnabrueck.de/handle/urn:nbn:de:gbv:700-202003262703.
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Building information extraction and reconstruction from satellite images is an essential task for many applications related to 3D city modeling, planning, disaster management, navigation, and decision-making. Building information can be obtained and interpreted from several data, like terrestrial measurements, airplane surveys, and space-borne imagery. However, the latter acquisition method outperforms the others in terms of cost and worldwide coverage: Space-borne platforms can provide imagery of remote places, which are inaccessible to other missions, at any time. Because the manual interpretation of high-resolution satellite image is tedious and time consuming, its automatic analysis continues to be an intense field of research. At times however, it is difficult to understand complex scenes with dense placement of buildings, where parts of buildings may be occluded by vegetation or other surrounding constructions, making their extraction or reconstruction even more difficult. Incorporation of several data sources representing different modalities may facilitate the problem. The goal of this dissertation is to integrate multiple high-resolution remote sensing data sources for automatic satellite imagery interpretation with emphasis on building information extraction and refinement, which challenges are addressed in the following: Building footprint extraction from Very High-Resolution (VHR) satellite images is an important but highly challenging task, due to the large diversity of building appearances and relatively low spatial resolution of satellite data compared to airborne data. Many algorithms are built on spectral-based or appearance-based criteria from single or fused data sources, to perform the building footprint extraction. The input features for these algorithms are usually manually extracted, which limits their accuracy. Based on the advantages of recently developed Fully Convolutional Networks (FCNs), i.e., the automatic extraction of relevant features and dense classification of images, an end-to-end framework is proposed which effectively combines the spectral and height information from red, green, and blue (RGB), pan-chromatic (PAN), and normalized Digital Surface Model (nDSM) image data and automatically generates a full resolution binary building mask. The proposed architecture consists of three parallel networks merged at a late stage, which helps in propagating fine detailed information from earlier layers to higher levels, in order to produce an output with high-quality building outlines. The performance of the model is examined on new unseen data to demonstrate its generalization capacity.
The availability of detailed Digital Surface Models (DSMs) generated by dense matching and representing the elevation surface of the Earth can improve the analysis and interpretation of complex urban scenarios. The generation of DSMs from VHR optical stereo satellite imagery leads to high-resolution DSMs which often suffer from mismatches, missing values, or blunders, resulting in coarse building shape representation. To overcome these problems, a methodology based on conditional Generative Adversarial Network (cGAN) is developed for generating a good-quality Level of Detail (LoD) 2 like DSM with enhanced 3D object shapes directly from the low-quality photogrammetric half-meter resolution satellite DSM input. Various deep learning applications benefit from multi-task learning with multiple regression and classification objectives by taking advantage of the similarities between individual tasks. Therefore, an observation of such influences for important remote sensing applications such as realistic elevation model generation and roof type classification from stereo half-meter resolution satellite DSMs, is demonstrated in this work. Recently published deep learning architectures for both tasks are investigated and a new end-to-end cGAN-based network is developed, which combines different models that provide the best results for their individual tasks.
To benefit from information provided by multiple data sources, a different cGAN-based work-flow is proposed where the generative part consists of two encoders and a common decoder which blends the intensity and height information within one network for the DSM refinement task. The inputs to the introduced network are single-channel photogrammetric DSMs with continuous values and pan-chromatic half-meter resolution satellite images. Information fusion from different modalities helps in propagating fine details, completes inaccurate or missing 3D information about building forms, and improves the building boundaries, making them more rectilinear.
Lastly, additional comparison between the proposed methodologies for DSM enhancements is made to discuss and verify the most beneficial work-flow and applicability of the resulting DSMs for different remote sensing approaches.
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Partovi, Tahmineh. "3D Building Model Reconstruction from Very High Resolution Satellite Stereo Imagery". Doctoral thesis, 2019. https://repositorium.ub.uni-osnabrueck.de/handle/urn:nbn:de:gbv:700-201910022067.
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Automatic three-dimensional (3D) building model reconstruction using remote sensing data is crucial in applications which require large-scale and frequent building model updates, such as disaster monitoring and urban management, to avoid huge manual efforts and costs. Recent advances in the availability of very high-resolution satellite data together with efficient data acquisition and large area coverage have led to an upward trend in their applications for 3D building model reconstructions. In this dissertation, a novel multistage hybrid automatic 3D building model reconstruction approach is proposed which reconstructs building models in level of details 2 (LOD2) based on digital surface model (DSM) data generated from the very high-resolution stereo imagery of the WorldView-2 satellite. This approach uses DSM data in combination with orthorectified panchromatic (PAN) and pan-sharpened data of multispectral satellite imagery to overcome the drawbacks of DSM data, such as blurred building boundaries, rough building shapes unwanted failures in the roof geometries. In the first stage, the rough building boundaries in the DSM-based building masks are refined by classifying the geometrical features of the corresponding PAN images. The refined boundaries are then simplified in the second stage through a parameterization procedure which represents the boundaries by a set of line segments. The main orientations of buildings are then determined, and the line segments are regularized accordingly. The regularized line segments are then connected to each other based on a rule-based method to form polygonal building boundaries. In the third stage, a novel technique is proposed to decompose the building polygons into a number of rectangles under the assumption that buildings are usually composed of rectangular structures. In the fourth stage, a roof model library is defined, which includes flat, gable, half-hip, hip, pyramid and mansard roofs. These primitive roof types are then assigned to the rectangles based on a deep learning-based classification method. In the fifth stage, a novel approach is developed to reconstruct watertight parameterized 3D building models based on the results of the previous stages and normalized DSM (nDSM) of satellite imagery. In the final stage, a novel approach is proposed to optimize building parameters based on an exhaustive search, so that the two-dimensional (2D) distance between the 3D building models and the building boundaries (obtained from building masks and PAN image) as well as the 3D normal distance between the 3D building models and the 3D point clouds (obtained from nDSM) are minimized. Different parts of the building blocks are then merged through a newly proposed intersection and merging process. All corresponding experiments were conducted on four areas of the city of Munich including 208 buildings and the results were evaluated qualitatively and quantitatively. According to the results, the proposed approach could accurately reconstruct 3D models of buildings, even the complex ones with several inner yards and multiple orientations. Furthermore, the proposed approach provided a high level of automation by the limited number of primitive roof model types required and by performing automatic parameter initialization. In addition, the proposed boundary refinement method improved the DSM-based building masks specified by 8 % in area accuracy. Furthermore, the ridge line directions and roof types were detected accurately for most of the buildings. The combination of the first three stages improved the accuracy of the building boundaries by 70 % in comparison to using line segments extracted from building masks without refinement. Moreover, the proposed optimization approach could achieve in most cases the best combinations of 2D and 3D geometrical parameters of roof models. Finally, the intersection and merging process could successfully merge different parts of the complex building models.