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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Análise de modelos digitais de superfície gerados a partir de imagens do sensor PRISM/ALOS / Analysis of digital surface models generated from images of PRISM/ ALOS sensor

Oliveira, Leila Freitas de 31 October 2011 (has links)
Made available in DSpace on 2015-03-26T13:28:05Z (GMT). No. of bitstreams: 1 texto completo.pdf: 2957688 bytes, checksum: ef8183fb03ec7b7417a321bf7d2a225e (MD5) Previous issue date: 2011-10-31 / The purpose of this study is the quality assessment of Digital Surface Models (DSMs) generated from stereo pairs of PRISM/ALOS images, considering aspects regarding different approaches of geometric correction, image matching strategies, grid distance and positional accuracy. The standard of accuracy expected for the products evaluated considers the Technical Standards of the National Cartography, defined by the Cartographic Accuracy Standard of the brazilian systematic mapping for 1:25,000 scale, class A. In the geometric correction step are considered the approaches of rigorous sensor model and generalized model using Rational Polynomial Coefficients (RPCs). The ground control points used in geometric correction and in global assessment of the positional accuracy of orthoimages and DSMs, were determined by GPS relative static positioning. The local assessments, aiming the analysis of DSMs as to different morphologies, are performed from control points determined by relative kinematic GPS positioning in low-slope surfaces and on inclined surfaces. The global results achieved indicate that the geometric modeling, the number of control points considered, as well as the strategies for image matching and grid distance influence the vertical accuracy of the DSM, in relation to the expected accuracy standard. The experiments performed to orthorectify the nadir images using the DSMs previously selected, show that variations as to these factors, beyond different vertical accuracies, not affect the expected horizontal accuracy of the orthoimage, portraying, therefore, the same horizontal quality standard for the MDSs used in the orthorectification. The statistical tests for trend and precision detection, confirm the relative consistency on all orthoimages and MDSs generated. However, most of these products presents trend, except for some isolated cases. As to the local assessment, the results indicate that different morphologies influence the accuracy of the DSM, in relation to global assessment. In general, the results in low-slope areas present greater accuracy. The local analyses also indicate that the slope, associated with factors such as failure image matching and interpolation procedures, provides degradation of DSM vertical accuracy. / O objetivo deste trabalho é a análise da qualidade de Modelos Digitais de Superfície (MDSs) gerados a partir de pares estereoscópicos de imagens do sensor PRISM/ALOS, considerando-se aspectos quanto a diferentes abordagens de correção geométrica, estratégias de correlação de imagens, espaçamento da grade e acurácia posicional. O padrão de acurácia esperado para os produtos avaliados considera as Normas Técnicas da Cartografia Nacional, através do Padrão de Exatidão Cartográfica (PEC) para a escala 1:25.000, classe A, do mapeamento sistemático brasileiro. Na etapa de correção geométrica são consideradas as abordagens do modelo rigoroso do sensor e do modelo generalizado com uso de Rational Polynomial Coefficients (RPCs). Os pontos de controle usados na correção geométrica, bem como para avaliação global da acurácia posicional de ortoimagens e MDSs, foram determinados por posicionamento GPS relativo estático. As avaliações locais, visando análise do comportamento dos MDSs segundo diferentes morfologias, são realizadas a partir de pontos de controle determinados por posicionamento GPS relativo cinemático, em superfícies de baixa declividade e em encostas de anfiteatros. Os resultados alcançados em nível global sinalizam que a modelagem geométrica utilizada, o número de pontos de controle considerados, assim como estratégias de correlação e espaçamento da grade influenciam a acurácia altimétrica dos MDSs, relativamente ao padrão de acurácia esperado. Os experimentos realizados para ortorretificar as imagens nadir com emprego de MDSs previamente selecionados, demonstram que variações quanto a esses fatores, além de acurácias altimétricas diferentes, não influenciam a qualidade planimétrica esperada para as ortoimagens, retratando, portanto, o mesmo padrão de qualidade planimétrica para os MDSs empregados na ortorretificação. Os testes estatísticos quanto à tendência e precisão confirmam a consistência relativa das ortoimagens e MDSs gerados, porém, a maioria desses produtos apresenta tendência, com exceção de alguns casos isolados. Quanto à avaliação local, os resultados indicam que diferentes morfologias influenciam a acurácia dos MDSs relativamente à análise global. De forma geral, áreas com menor declividade apresentam resultados com maior acurácia. As análises locais indicam ainda que a variável declividade, associada a fatores como a falha na correlação e procedimentos de interpolação, proporciona degradação da acurácia altimétrica dos MDSs.
12

Extrakce krajinných prvků z dat dálkového průzkumu / Extraction Landscape Elements from Remote Sensing Data

Martinová, Olga January 2013 (has links)
In this thesis, an approach to automatically derive information about land cover from the remotely sensed data is presented. The data interpretation was done with classification process and performed in software eCognition Developer. The Object-based image analysis, which assignes the classes - for example land cover types, to clusters of pixels (=objects), was used. For the classification, products of two different data sources were combined - the orthophotos generated from aerial imagery and Normalized Digital surface model derived from LiDAR data. Five types of landscape elements were identified and classified.
13

Zpracování snímků pořízených pomocí UAV / Processing of images taken from UAV

Ptáček, Ondřej January 2014 (has links)
This diploma thesis deals with the processing and evaluation of the pictures taken by unmanned aerial vehicles - UAV. The introductory part is devoted to the definition, use, applications and types of UAV especially for photogrammetric purposes. Also the software equipment is described, including a description and examples of several types of possible outcomes. Further the measurements, computational works and process of elaboration in used software programs are described. Achieved outcomes of elaboration are also presented. In conclusion, the overall evaluation and assessment of the results of measurement is done of set of points.
14

Earth Observation and Stereo Vision / Observation de la Terre et stéréoscopie

De Franchis, Carlo 05 October 2015 (has links)
Cette thèse étudie les problèmes posés par l’estimation automatique de modèles numériques d’élévation de la surface terrestre à partir de photographies prises par des satellites. Ce travail a bénéficié d’une collaboration avec le CNES (Centre National d’Etudes Spatiales) sur le développement d’outils de vision stéréoscopique pour Pléiades, le premier satellite d’observation de la Terre capable de produire des paires ou triplets d’images quasi-simultanées. Le premier chapitre de la thèse décrit un modèle simplifié de caméra pushbroom destiné aux satellites d’observation de la Terre, et aborde le problème de la correction des données de calibration en faisant intervenir des mesures externes. Ce chapitre propose un nouvel algorithme pour affiner les paramètres d’orientation du satellite à partir d’un jeu de points de contrôle. Il est utilisable pour tous les satellites munis de caméras pushbroom. Dans le but d’appliquer aux images satellitaires les nombreux algorithmes de mise en correspondance stéréoscopique développés en traitement d’images et en vision par ordinateur, le deuxième chapitre explore l’adaptation de la théorie de la rectification épipolaire aux images prises par des caméras pushbroom. La rectification épipolaire est utilisée habituellement pour réduire la complexité du problème de mise en correspondance stéréoscopique, et permet d’appliquer les algorithmes les plus récents à des images satellitaires. Le chapitre suivant étudie les effets des erreurs de calibration géométrique sur la rectification et propose une méthode pour éliminer leur impact sur la mise en correspondance. Le quatrième chapitre décrit et analyse en détails une implémentation de l’algorithme Semi-Global Matching (SGM), classé actuellement parmi les meilleurs algorithmes de mise en correspondance stéréoscopique. En se fondant sur une réinterprétation récente de SGM, ce chapitre en propose une variante qui permet de réduire d’un facteur cinq son écart en énergie par rapport aux algorithmes de référence pour la minimisation de champs aléatoires de Markov. En assemblant les blocs algorithmiques décrits dans les chapitres précédents, le cinquième chapitre décrit S2P, une chaîne stéréoscopique complète qui produit des modèles numériques d’élévation à partir d’images satellitaires. Un modèle d’évolution de paysage est présenté dans le sixième chapitre comme exemple d’application. Le modèle est utilisé pour simuler numériquement la structure fine du réseau hydrographique sur des modèles numériques d’élévation obtenus à partir d’images prises par Pléiades. Le code source de la chaîne S2P2 est distribué en tant que logiciel open source. Afin d’assurer la reproductibilité des résultats obtenus, les algorithmes implémentés dans S2P sont en cours de publication dans le journal IPOL, accompagnés de descriptions et d’analyses détaillées, de codes sources documentés et de démonstrateurs en ligne. / This thesis deals with the problem of computing accurate digital elevationmodels of the Earth's surface from optical images taken by pushbroomobservation satellites. It takes advantage of the collaboration of thedefendant with CNES (the French Space Agency) on the development ofstereo vision tools for Pléiades, the first Earth observation satelliteproducing quasi simultaneous stereo pairs or triplets with small baseline.The first chapter describes a simple pushbroom camera model for observationsatellites orbiting around the Earth and addresses the correction of theacquisition geometry by involving extrinsic information. This chapter proposesa new algorithm to refine the orientation parameters from a set of groundcontrol points, applicable to all pushbroom satellites.With the goal of testing for satellite imaging the thriving exploration ofstereo matching by the computer vision community, the second chapter exploresthe adaptation of the theory of epipolar resampling to pushbroom images.Epipolar resampling is traditionally used in stereo to reduce the matchingcomputational cost, and permits to test for satellite imaging the mostcompetitive computer vision algorithms. The third chapter discusses the effectsof geometric calibration inaccuracies and proposes a method to cancel itsimpact on stereo matching.The fourth chapter analyzes and describes a detailed implementation of theSemi-Global Matching (SGM) algorithm, which is currently among the top-rankedstereo vision algorithms. Based on a recently proposed interpretation of SGM asa min-sum Belief Propagation algorithm, a variant is proposed that allows toreduce by a factor five the energy gap of SGM with respect to referencealgorithms for Markov Random Fields with truncated smoothness terms.By wrapping together the algorithmic blocks described in the previous chapters,the fifth chapter describes S2P, a complete stereo pipeline for producingdigital elevation models from satellite images. As an application, a landscapeevolution model is presented in the sixth chapter. The model is used tosimulate numerically the fine structure of the river networks on digitalelevation models obtained from Pléiades Earth observation images.The source code of the S2P stereo pipeline is distributed as open source. Toensure reproducibility, the algorithms implemented in each step of the S2Ppipeline are submitted to the IPOL journal, with detailed descriptions of thealgorithms, documented source codes and online demonstrations for each block ofthe pipeline.
15

Characterizing Disaster Resilience Using Very High Resolution Time-Sequence Stereo Imagery

Julius, Alexandria Marie 19 December 2018 (has links)
No description available.
16

On the modelling of solar radiation in urban environments – applications of geomatics and climatology towards climate action in Victoria

Krasowski, Christopher B. 04 October 2019 (has links)
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
17

利用近紅外光影像之近景攝影測量建立數值表面模型之研究 / Construction of digital surface model using Near-IR close range photogrammetry

廖振廷, Liao, Chen Ting Unknown Date (has links)
點雲(point cloud)為以大量三維坐標描述地表實際情形的資料形式,其中包含其三維坐標及相關屬性。通常點雲資料取得方式為光達測量,其以單一波段雷射光束掃描獲取資料,以光達獲取點雲,常面臨掃描時間差、缺乏多波段資訊、可靠邊緣線及角點資訊、大量離散點雲又缺乏語意資訊(semantic information)難以直接判讀及缺乏多餘觀測量等問題。 攝影測量藉由感測反射自太陽光或地物本身放射之能量,可記錄為二維多光譜影像,透過地物在不同光譜範圍表現之特性,可輔助分類,改善分類成果。若匹配多張高重疊率的多波段影像,可以獲取包含多波段資訊且位於明顯特徵點上的點雲,提供光達以外的點雲資料來源。 傳統空中三角測量平差解算地物點坐標及產製數值表面模型(Digital Surface Model, DSM)時,多採用可見光影像為主;而目前常見之高空間解析度數值航照影像,除了記錄可見光波段之外,亦可蒐集近紅外光波段影像。但較少採用近紅外光波段影像,以求解地物點坐標及建立DSM。 因此本研究利用多波段影像所蘊含的豐富光譜資訊,以取像方式簡易及低限制條件的近景攝影測量方式,匹配多張可見光、近紅外光及紅外彩色影像,分別建立可見光、近紅外光及紅外彩色之DSM,其目的在於探討加入近紅外光波段後,所產生的近紅外光及紅外彩色DSM,和可見光DSM之異同;並比較該DSM是否更能突顯植被區。 研究顯示,以可見光點雲為檢核資料,計算近紅外光與紅外彩色點雲的均方根誤差為其距離門檻值之相對檢核方法,可獲得約21%的點雲增加率;然而使用近紅外光或紅外彩色影像,即使能增加點雲資料量,但對於增加可見光影像未能匹配的資料方面,其效果仍屬有限。 / Point cloud represents the surface as mass 3D coordinates and attributes. Generally, these data are usually collected by LIDAR (LIght Detection And Ranging), which acquires data through single band laser scanning. But the data collected by LIDAR could face problems, such as scanning process is not instantaneous, lack of multispectral information, breaklines, corners, semantic information and redundancies. However, photogrammetry record the electromagnetic energy reflected or emitted from the surface as 2D multispectral images, via ground features with different characteristics differ in spectrum, it can be classified more efficiently and precisely. By matching multiple high overlapping multispectral images, point cloud including multispectral information and locating on obvious feature points can be acquired. This provides another point cloud source aparting from LIDAR. In most studies, visible light (VIS) images are used primarily, while calculating ground point coordinates and generating digital surface models (DSM) through aerotriangulation. Although nowadays, high spatial resolution digital aerial images can acquire not only VIS channel, but also near infrared (NIR) channel as well. But there is lack of research doing the former procedures by using NIR images. Therefore, this research focuses on the rich spectral information in multispectral images, by using easy image collection and low restriction close range photogrammetry method. It matches several VIS, NIR and color infrared (CIR) images, and generate DSMs respectively. The purpose is to analyze the difference between VIS, NIR and CIR data sets, and whether it can emphasize the vegetation area, after adding NIR channel in DSM generation. The result shows that by using relative check points between NIR, CIR data with VIS one. First, VIS point cloud was set as check point data, then, the RMSE (Root Mean Square Error) of NIR and CIR point cloud was calculated as distance threshold. Its data increment is 21% ca. However, the point cloud data amount can be increased, by matching NIR and CIR images. But the effect of increasing data, which was not being matched from VIS images are limited.
18

Development of a digital orthophoto generation system for analysis of forest canopy dynamics

ITAYA, Akemi, 板谷, 明美, YAMAMOTO, Shin-Ichi, 山本, 進一 12 1900 (has links) (PDF)
農林水産研究情報センターで作成したPDFファイルを使用している。
19

Uso de veículos aéreos não tripulados para mapeamento e avaliação de erosão urbana / Use of unmanned arial vehicles (UAV) for mapping and evaluating urban erosion (in Goiás state, Brazil)

Rodrigues , Avilmar Antonio 25 November 2016 (has links)
Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2016-12-27T11:27:00Z No. of bitstreams: 2 Dissertação - Avilmar Antonio Rodrigues - 2016.pdf: 13580117 bytes, checksum: 2b78a395b4bd955f8d72e83399bcc578 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-12-27T11:27:20Z (GMT) No. of bitstreams: 2 Dissertação - Avilmar Antonio Rodrigues - 2016.pdf: 13580117 bytes, checksum: 2b78a395b4bd955f8d72e83399bcc578 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-12-27T11:27:20Z (GMT). No. of bitstreams: 2 Dissertação - Avilmar Antonio Rodrigues - 2016.pdf: 13580117 bytes, checksum: 2b78a395b4bd955f8d72e83399bcc578 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-11-25 / 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.
20

Podklady pro tvorbu mapy pro orientační běh / Data for the Creation Orienteering Maps

Panchártek, Jan January 2013 (has links)
This thesis is about using airborne laser scanning data for making maps for Orienteering. In this thesis were used altimetry data DMR 4G and DMR 5G. These data are provided by ČUZK. The control measuring was made in choosen area to verify the accuracy. In this thesis is described procedure of data collection and their treatment. The results of this thesis are two illustrations of the orienteering maps.

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