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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

Target Types and Placement for Terrestrial and Mobile Mapping

Scott M. Peterson (5930144) 03 January 2019 (has links)
The use of digital three-dimensional (3D) data has increased over the last two decades as private and public firms have begun to realize its utility. Mobile Terrestrial Laser Scanning (MTLS) or Mobile Mapping Systems (MMS), which utilizes LiDAR (Light Detection and Ranging) data collection from a moving platform along with advances in positioning systems—e.g., Global Navigation Satellite Systems (GNSS), Inertial Navigation Systems (INS), and Distance Measurement Instruments (DMIs)—have paved the way for efficient, abundant, and accurate 3D data collection. Validation and control targets are vital to ensure relative and/or absolute accuracy for MTLS projects. The focus of this dissertation is to evaluate several types of targets and the positional spacing of said targets for MTLS.<div><br></div><div>A mostly planar two-dimensional (2D) targeting system (painted target on ground) is commonly used to constrain, register, and validate the 3D point clouds from MTLS. In this dissertation, 3D objects—a sphere and a cube—were evaluated with varied angles of incidence and point densities as more appropriate alternatives to constrain and validate the 3D MTLS point clouds. Next, a planar circular 2D target—with the use of the raw intensity of the LiDAR pulse as another measured dimension—was evaluated as a proof of concept to also constrain and validate 3D LiDAR data. A third and final component of this dissertation explored analyses of INS data to determine the positional spacing of control and validation targets in MTLS projects to provide maximum accuracy for all data points.<br></div>
12

Georreferenciamento automático de placas de sinalização com imagens obtidas com um sistema móvel de mapeamento / Automatic georeferencing of traffic signs with images took from a mobile mapping system

Francisco Assis da Silva 27 June 2012 (has links)
A detecção e reconhecimento de objetos em ambiente não controlado tem aplicações diversas no campo da visão computacional, e juntamente com o georreferenciamento de objetos de forma automática propicia uma variedade de aplicações, como por exemplo, o mapeamento da sinalização de trânsito. Os sinais de trânsito são muito importantes por proverem regras de navegação nas ruas e estradas. Um sistema para a determinação das posições geográficas de placas de sinalização de trânsito em áreas urbanas de forma automática constitui uma ferramenta útil para a gestão municipal podendo servir para tomadas de decisão, como por exemplo, fluxo de tráfego e definição de sinalização nas vias terrestres. Do ponto de vista prático, um sistema com estas características tem uma grande complexidade na implementação o que caracteriza um grande desafio. Diante do contexto exposto, nesta tese, é tratada a computação da detecção, o reconhecimento de sinais e o georreferenciamento de placas de trânsito. A implementação deste trabalho consistiu na coleta de conjuntos de dados e a aplicação de algoritmos para a extração dos descritores de pontos chave e para realizar a correspondências dos pontos chave entre duas imagens (imagem de uma via contendo uma ou mais placas e imagem de um template de uma placa de sinalização). Uma vez obtidos apenas os pontos em comuns referentes aos seus descritores, na sequência foram aplicados algoritmos para a detecção, reconhecimento e georreferenciamento das placas de trânsito. Para a obtenção do conjunto de dados foi utilizado um sistema móvel de mapeamento terrestre, equipado com sensores de imageamento digital, que além de obter conjuntos de sequências de imagens, também capturam informações de navegação e posicionamento. Para a detecção e reconhecimento foram utilizados algoritmos já consolidados na literatura (SIFT e BBF) e também algoritmos definidos e implementados para a realização da metodologia proposta. Para a extração de pontos chave condizentes com a placa a ser detectada, foi desenvolvido um algoritmo, pelo fato dos algoritmos citados na literatura não serem adequados para imagens que apresentam poucos pontos de correspondência, como é o caso do algoritmo RANSAC. Foi também definido e implementado um algoritmo para o reconhecimento de caracteres para o caso de placas de sinalização que especificam limite de velocidade. Com o conhecimento das fotocoordenadas centrais referentes às placas detectadas e reconhecidas e os dados de navegação e posicionamento, é realizado o georreferenciamento a fim de determinar as posições das placas no terreno por meio das equações de colinearidade. Foram realizados experimentos iniciais comprovando que a metodologia proposta é adequada para os objetivos definidos. As taxas de acerto na detecção e reconhecimento das placas de sinalização atingiram valores superiores a 80%, mesmo utilizando imagens com cenas complexas. O trabalho desenvolvido contribui com a metodologia proposta destinada à determinação das posições das feições dos sinais de trânsito em áreas urbanas, e na Área de Visão Computacional, contribui com novos algoritmos para a detecção e reconhecimento de placas de sinalização, bem como um novo algoritmo para o reconhecimento de caracteres. / The detection and object recognition in uncontrolled environment has several applications in the field of computer vision, and together with automatic georeferencing of objects provides a variety of applications, for example, the mapping of traffic signs. Traffic signs are very important because they provide navigation rules in streets and roads. A system for the automatic determining of the geographic positions of traffic sign plates in urban areas constitutes a useful tool for municipal management, it can be used for decision making, such as traffic flow and sign location on roads. From a practical point of view, a system with these characteristics has a great complexity in the implementation that characterizes a great challenge. Considering the exposed context, this thesis treats the computation of detection, recognition and georeferencing of traffic signs. The implementation of this work consisted in collecting data sets and application of algorithms for extracting keypoint features and performing the keypoint matching between two images (image of a road containing one or more plates and image of a template from a traffic sign). Once only the points in common in relation to their descriptors had been obtained, in the sequence, some algorithms were applied to the detection, recognition and georeferencing of traffic signs. To obtain the data set a landbase mobile mapping system was used, equipped with digital imaging sensors, which in addition to obtaining sets of image sequences, they also capture navigation information and positioning. For detection and recognition algorithms already established in literature (SIFT and BBF) were used and algorithms defined and implemented to the realization of the proposed methodology were also used. For the extraction of keypoints suitable with the plateto be detected, an algorithm was developed, because of the algorithms mentioned in literature are not appropriate for images that have few points of matching such as the RANSAC algorithm. An algorithm for recognition of characters for the case of signs which specify the speed limit was also defined and implemented. With the knowledge of the central photo coordinates referring to plates detected and recognized and navigation and positioning data,the georeferencing is performed to determine the positions of the plates on the ground through the collinearity equations. Initial experiments were performed demonstrating that the proposed methodology is appropriate for the defined goals. The hit rates of detection and recognition of sign plates reached values above 80%, even using images with complex scenes. The developed work contributes with the proposed methodology destined to the determination of traffic signs positions in urban areas, and in the Computer Vision Area, it contributes with new algorithms for the detection and recognition of traffic signs and a new algorithm for character recognition.
13

Georreferenciamento automático de placas de sinalização com imagens obtidas com um sistema móvel de mapeamento / Automatic georeferencing of traffic signs with images took from a mobile mapping system

Silva, Francisco Assis da 27 June 2012 (has links)
A detecção e reconhecimento de objetos em ambiente não controlado tem aplicações diversas no campo da visão computacional, e juntamente com o georreferenciamento de objetos de forma automática propicia uma variedade de aplicações, como por exemplo, o mapeamento da sinalização de trânsito. Os sinais de trânsito são muito importantes por proverem regras de navegação nas ruas e estradas. Um sistema para a determinação das posições geográficas de placas de sinalização de trânsito em áreas urbanas de forma automática constitui uma ferramenta útil para a gestão municipal podendo servir para tomadas de decisão, como por exemplo, fluxo de tráfego e definição de sinalização nas vias terrestres. Do ponto de vista prático, um sistema com estas características tem uma grande complexidade na implementação o que caracteriza um grande desafio. Diante do contexto exposto, nesta tese, é tratada a computação da detecção, o reconhecimento de sinais e o georreferenciamento de placas de trânsito. A implementação deste trabalho consistiu na coleta de conjuntos de dados e a aplicação de algoritmos para a extração dos descritores de pontos chave e para realizar a correspondências dos pontos chave entre duas imagens (imagem de uma via contendo uma ou mais placas e imagem de um template de uma placa de sinalização). Uma vez obtidos apenas os pontos em comuns referentes aos seus descritores, na sequência foram aplicados algoritmos para a detecção, reconhecimento e georreferenciamento das placas de trânsito. Para a obtenção do conjunto de dados foi utilizado um sistema móvel de mapeamento terrestre, equipado com sensores de imageamento digital, que além de obter conjuntos de sequências de imagens, também capturam informações de navegação e posicionamento. Para a detecção e reconhecimento foram utilizados algoritmos já consolidados na literatura (SIFT e BBF) e também algoritmos definidos e implementados para a realização da metodologia proposta. Para a extração de pontos chave condizentes com a placa a ser detectada, foi desenvolvido um algoritmo, pelo fato dos algoritmos citados na literatura não serem adequados para imagens que apresentam poucos pontos de correspondência, como é o caso do algoritmo RANSAC. Foi também definido e implementado um algoritmo para o reconhecimento de caracteres para o caso de placas de sinalização que especificam limite de velocidade. Com o conhecimento das fotocoordenadas centrais referentes às placas detectadas e reconhecidas e os dados de navegação e posicionamento, é realizado o georreferenciamento a fim de determinar as posições das placas no terreno por meio das equações de colinearidade. Foram realizados experimentos iniciais comprovando que a metodologia proposta é adequada para os objetivos definidos. As taxas de acerto na detecção e reconhecimento das placas de sinalização atingiram valores superiores a 80%, mesmo utilizando imagens com cenas complexas. O trabalho desenvolvido contribui com a metodologia proposta destinada à determinação das posições das feições dos sinais de trânsito em áreas urbanas, e na Área de Visão Computacional, contribui com novos algoritmos para a detecção e reconhecimento de placas de sinalização, bem como um novo algoritmo para o reconhecimento de caracteres. / The detection and object recognition in uncontrolled environment has several applications in the field of computer vision, and together with automatic georeferencing of objects provides a variety of applications, for example, the mapping of traffic signs. Traffic signs are very important because they provide navigation rules in streets and roads. A system for the automatic determining of the geographic positions of traffic sign plates in urban areas constitutes a useful tool for municipal management, it can be used for decision making, such as traffic flow and sign location on roads. From a practical point of view, a system with these characteristics has a great complexity in the implementation that characterizes a great challenge. Considering the exposed context, this thesis treats the computation of detection, recognition and georeferencing of traffic signs. The implementation of this work consisted in collecting data sets and application of algorithms for extracting keypoint features and performing the keypoint matching between two images (image of a road containing one or more plates and image of a template from a traffic sign). Once only the points in common in relation to their descriptors had been obtained, in the sequence, some algorithms were applied to the detection, recognition and georeferencing of traffic signs. To obtain the data set a landbase mobile mapping system was used, equipped with digital imaging sensors, which in addition to obtaining sets of image sequences, they also capture navigation information and positioning. For detection and recognition algorithms already established in literature (SIFT and BBF) were used and algorithms defined and implemented to the realization of the proposed methodology were also used. For the extraction of keypoints suitable with the plateto be detected, an algorithm was developed, because of the algorithms mentioned in literature are not appropriate for images that have few points of matching such as the RANSAC algorithm. An algorithm for recognition of characters for the case of signs which specify the speed limit was also defined and implemented. With the knowledge of the central photo coordinates referring to plates detected and recognized and navigation and positioning data,the georeferencing is performed to determine the positions of the plates on the ground through the collinearity equations. Initial experiments were performed demonstrating that the proposed methodology is appropriate for the defined goals. The hit rates of detection and recognition of sign plates reached values above 80%, even using images with complex scenes. The developed work contributes with the proposed methodology destined to the determination of traffic signs positions in urban areas, and in the Computer Vision Area, it contributes with new algorithms for the detection and recognition of traffic signs and a new algorithm for character recognition.
14

En utredning av tekniken "mobile mapping" i kommunal verksamhet

Parianos, Andreas, Dahlqvist, Tobias January 2010 (has links)
<p>This thesis work is intended to analyze whether the municipalities has a need for the new technology of mobile mapping.</p><p>Mobile mapping consists of the technologies of laser scanning, photographing and positioning of streets and roads in city environment and in the countryside. When these technologies are operating together a georeferenced three-dimensional image model is created, which has specific coordinates that states its position on the surface of the earth. Thanks to the laser scanning process even measuring can be performed in this model.</p><p>The municipal sector consists of many different departments which use visual spatial information. These departments are an interesting target group for this system. Specific departments within the municipal sector, which we considered were the most suitable, have been selected. Individuals within these departments have replied to a <em>questionnaire</em> where several statements were given. The statements are constructed so that the replies that are received as much as possible describe the need for this new technology. In addition to the <em>questionnaire</em> a number of telephone- and in-depth interviews have been done in purpose of creating a basis which is as solid as possible.</p><p>The results that have been obtained indicate that there is a rather considerable demand for the technology. The majority of the asked professions have given replies which hint that they would appreciate visual measurable spatial information in accurate and detailed 3D-models. The telephone interviews have pointed in this direction as well.</p><p>Since a municipality is organized of a large number of departments which each have a need for the technology, a reference can be made to the expression “many a little makes a mickle”. In other words, the municipal need for the technology is considerable since many different units find their own uses for mobile mapping.</p><p>We have after this investigation obtained a result which implies that mobile mapping would be a good investment for the municipal sector.</p>
15

En utredning av tekniken "mobile mapping" i kommunal verksamhet

Parianos, Andreas, Dahlqvist, Tobias January 2010 (has links)
This thesis work is intended to analyze whether the municipalities has a need for the new technology of mobile mapping. Mobile mapping consists of the technologies of laser scanning, photographing and positioning of streets and roads in city environment and in the countryside. When these technologies are operating together a georeferenced three-dimensional image model is created, which has specific coordinates that states its position on the surface of the earth. Thanks to the laser scanning process even measuring can be performed in this model. The municipal sector consists of many different departments which use visual spatial information. These departments are an interesting target group for this system. Specific departments within the municipal sector, which we considered were the most suitable, have been selected. Individuals within these departments have replied to a questionnaire where several statements were given. The statements are constructed so that the replies that are received as much as possible describe the need for this new technology. In addition to the questionnaire a number of telephone- and in-depth interviews have been done in purpose of creating a basis which is as solid as possible. The results that have been obtained indicate that there is a rather considerable demand for the technology. The majority of the asked professions have given replies which hint that they would appreciate visual measurable spatial information in accurate and detailed 3D-models. The telephone interviews have pointed in this direction as well. Since a municipality is organized of a large number of departments which each have a need for the technology, a reference can be made to the expression “many a little makes a mickle”. In other words, the municipal need for the technology is considerable since many different units find their own uses for mobile mapping. We have after this investigation obtained a result which implies that mobile mapping would be a good investment for the municipal sector.
16

Automação do caminhamento fotogramétrico com arranjo triangular de câmeras em trajetória curva /

Patuci, Tobias Rehder da Cunha January 2017 (has links)
Orientador: João Fernando Custódio da Silva / Resumo: Um sistema de mapeamento móvel (SMM) permite obter informações geográficas das vias e de seu entorno. O objetivo deste trabalho é controlar a propagação de erros na determinação dos POE no processo de caminhamento fotogramétrico, para isto, foi estudada a adição de uma terceira câmera ao sistema e a integração das imagens com dados dos sensores de posicionamento e navegação. As câmeras foram dispostas em um arranjo triangular, de modo que o terceiro raio homólogo de um ponto fosse não coplanar aos demais raios homólogos deste mesmo ponto. Isto permite melhorar a estimativa da posição geométrica dos pontos, principalmente no sentido transversal à base do levantamento. Para a realização do levantamento, o sistema foi calibrado no campo de calibração da FCT/Unesp. O trajeto percorrido foi no entorno de uma quadra urbana, de modo a percorrer trechos retos e curvos. Os algoritmos SIFT (Scale Invariant Feature Transform) e RANSAC (RANdom SAmple Consensus) foram aplicados nas imagens coletadas pelo sistema, a fim de identificar os pontos homólogos nos trios de imagens e nas imagens subsequentes. Os parâmetros de orientação exterior (POE) das câmeras foram calculados pelo processo de fototriangulação, o ajustamento foi pelo método dos mínimos quadrados (MMQ), modelo paramétrico. Os dados foram processados variandose a quantidade de câmeras, duas ou três, para analisar a contribuição da terceira câmera. Os experimentos foram realizados para trechos retos e curvos e variou-se o tamanho... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: A mobile mapping system (MMS) provides geographical information of the roads and their surroundings. When carried by pedestrians, it can provide information of indoor areas or inaccessible to vehicles. The objective of this work was to control the spread of errors in determining the EOP in photogrammetric traversal process to this, the addition of a third camera to the system and the integration of images and positioning and navigation sensors data were studied. Cameras were mounted in a triangular arrangement, in a way that the third homologous beam of a point is non-colinear to the others homologous beams of the same point. This enables a point position estimative enhancement, mainly in the transverse direction of the base. For the survey, the system was calibrated in the FCT/Unesp calibration field. The route taken was in the vicinity of an urban block, passing by straight and curved sections. SIFT algorithm (Scale Invariant Feature Transform) and RANSAC (RANdom SAmple Consensus) were applied on the images collected by the system to identify the corresponding points in image trios and subsequent images. The exterior orientation parameters (EOP) of the cameras were calculated by the phototriangulation process, the adjustment method used was the least squares (LSM), parametric model. The data were processed by varying the number of cameras, two or three, to analyze the contribution of the third camera. The experiments were realized for straight and curved sections and was va... (Complete abstract click electronic access below) / Mestre
17

Living the map : mobile mapping in post/colonial cities

Wilmott, Clancy January 2017 (has links)
This thesis is concerned with mobile mapping practices in Sydney and Hong Kong. Since the development of mobile media technology, there has been widespread proliferation of geo-locative, quasi-cartographic mapping practices in which people use applications (apps) on their mobile phones to narrate and navigate their way through urban spaces. This has raised questions within scholarly communities about the impact that these new technologies are having on everyday practices and everyday lives. As such, this thesis seeks to contribute to a growing field of knowledge surrounding the transformation of wayfinding, navigational and spatial mapping in the wake of these developments. Focusing an empirical investigation in two post/colonial cities - Sydney and Hong Kong - it draws on ethnographic, archival and geographical data in order to situate mobile mapping in an everyday context. Building upon Foucault's work on order (2002b), knowledge (2002a) and discipline (1995), this thesis seeks to address the issue of power-knowledge relations within and without mobile mapping practices as political and generative contestations over the meaning of space, the potentiality of practice and the indeterminacy of the past. It does so by considering an over-arching discourse of cartographic reason, best articulated by Farinelli (1998) and Olsson (1998) as a rationalist, universalist and geometrical approach to spatial understanding. Moving beyond the Cartesian interpretation of cartographic reason, it argues that in an increasingly digitised and monadic world, analyses of cartographic discourse must expand into an investigation of the role of Leibnizian binary systems, universal characteristics and elasticity. As such, this thesis engages three heuristic lenses - space, technology and people - with which to understand the empirical material from different perspectives. It argues that digital mobile mapping practices can be understood as expanded and transformative descendants of the rationalist, universalist and scientific impulses that have characterised cartographic reason since the Enlightenment. However, where continuity can be traced across many different cartographic and mapping practices, as the power of cartographic reason continues to reassert authority and territorialise space and knowledge, equally, the contestations which where borne of initial and early colonial encounters continue to generate contestation, conflict and hauntings.
18

Automação do caminhamento fotogramétrico com arranjo triangular de câmeras em trajetória curva / Automation of photogrammetric bridging using a triangular camera array in curved trajectories

Patuci, Tobias Rehder da Cunha 16 December 2017 (has links)
Submitted by Tobias Rehder da Cunha Patuci null (tobiasrehder@hotmail.com) on 2018-02-05T13:35:54Z No. of bitstreams: 1 diss_qualif_final.pdf: 48075089 bytes, checksum: add7dc77ed0089fb6e3ef138bf65abbc (MD5) / Approved for entry into archive by ALESSANDRA KUBA OSHIRO ASSUNÇÃO (alessandra@fct.unesp.br) on 2018-02-05T17:08:27Z (GMT) No. of bitstreams: 1 patuci_trc_me_prud.pdf: 48075089 bytes, checksum: add7dc77ed0089fb6e3ef138bf65abbc (MD5) / Made available in DSpace on 2018-02-05T17:08:28Z (GMT). No. of bitstreams: 1 patuci_trc_me_prud.pdf: 48075089 bytes, checksum: add7dc77ed0089fb6e3ef138bf65abbc (MD5) Previous issue date: 2017-12-16 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Um sistema de mapeamento móvel (SMM) permite obter informações geográficas das vias e de seu entorno. O objetivo deste trabalho é controlar a propagação de erros na determinação dos POE no processo de caminhamento fotogramétrico, para isto, foi estudada a adição de uma terceira câmera ao sistema e a integração das imagens com dados dos sensores de posicionamento e navegação. As câmeras foram dispostas em um arranjo triangular, de modo que o terceiro raio homólogo de um ponto fosse não coplanar aos demais raios homólogos deste mesmo ponto. Isto permite melhorar a estimativa da posição geométrica dos pontos, principalmente no sentido transversal à base do levantamento. Para a realização do levantamento, o sistema foi calibrado no campo de calibração da FCT/Unesp. O trajeto percorrido foi no entorno de uma quadra urbana, de modo a percorrer trechos retos e curvos. Os algoritmos SIFT (Scale Invariant Feature Transform) e RANSAC (RANdom SAmple Consensus) foram aplicados nas imagens coletadas pelo sistema, a fim de identificar os pontos homólogos nos trios de imagens e nas imagens subsequentes. Os parâmetros de orientação exterior (POE) das câmeras foram calculados pelo processo de fototriangulação, o ajustamento foi pelo método dos mínimos quadrados (MMQ), modelo paramétrico. Os dados foram processados variandose a quantidade de câmeras, duas ou três, para analisar a contribuição da terceira câmera. Os experimentos foram realizados para trechos retos e curvos e variou-se o tamanho do bloco processado e o avanço de base. Além disso, foi analisada a diferença entre o processamento em lote e sequencial. O controle de qualidade foi realizado pela análise da raíz do erro médio quadrático, comparando-se as coordenadas obtidas na fototriangulação com as coordenadas medidas em campo, em um levantamento topográfico. Os experimentos mostraram que com a adição da terceira câmera foram obtidos melhores resultados, principalmente para a trajetória curva. / A mobile mapping system (MMS) provides geographical information of the roads and their surroundings. When carried by pedestrians, it can provide information of indoor areas or inaccessible to vehicles. The objective of this work was to control the spread of errors in determining the EOP in photogrammetric traversal process to this, the addition of a third camera to the system and the integration of images and positioning and navigation sensors data were studied. Cameras were mounted in a triangular arrangement, in a way that the third homologous beam of a point is non-colinear to the others homologous beams of the same point. This enables a point position estimative enhancement, mainly in the transverse direction of the base. For the survey, the system was calibrated in the FCT/Unesp calibration field. The route taken was in the vicinity of an urban block, passing by straight and curved sections. SIFT algorithm (Scale Invariant Feature Transform) and RANSAC (RANdom SAmple Consensus) were applied on the images collected by the system to identify the corresponding points in image trios and subsequent images. The exterior orientation parameters (EOP) of the cameras were calculated by the phototriangulation process, the adjustment method used was the least squares (LSM), parametric model. The data were processed by varying the number of cameras, two or three, to analyze the contribution of the third camera. The experiments were realized for straight and curved sections and was varied the block size and base advance. Moreover, it was analysed the difference between sequential and full block calculation. Quality control was held by root mean square error analysis, comparing coordinates obtained in phototriangulation with object coordinates obtained by topographic survey. Finally, the experiments presented better results with the third camera addition, mainly for the curved section. / 131910/2015-9
19

Caminhamento fotogramétrico utilizando o fluxo óptico filtrado /

Barbosa, Ricardo Luís. January 2006 (has links)
Resumo: Em certas condições, os sensores de orientação e posicionamento (INS e GPS) de um Sistema Móvel de Mapeamento Terrestre (SMMT) ficam indisponíveis por algum intervalo de tempo casionando a perda da orientação e do posicionamento das imagens capturadas neste intervalo. Neste trabalho, é proposta uma solução baseada apenas nas imagens sem a utilização de sensores ou informações externas às mesmas, através do fluxo óptico. Um sistema móvel com um par de vídeo câmaras, denominado Unidade Móvel de Mapeamento Digital (UMMD), foi utilizado para testar a metodologia proposta em uma via plana. As câmaras são fixadas em uma base com um afastamento entre as câmaras de 0,94m e paralelas ao eixo de deslocamento (Y). A velocidade do veículo é estimada, inicialmente, com base no fluxo óptico denso. Em seguida, a estimação da velocidade é melhorada após uma filtragem, que consiste em: utilizar os vetores que apresentam comportamento radial na metade inferior das imagens e que foram detectados pelo algoritmo de Canny, acrescida uma segunda etapa na estimação da velocidade com eliminação de erros grosseiros. Com a velocidade estimada e sabendo-se o tempo de amostragem do vídeo, o deslocamento de cada imagem é determinado e esta informação é utilizada como aproximação inicial para o posicionamento das câmaras. Os resultados mostraram que a velocidade estimada ficou próxima da velocidade verdadeira e a qualidade do ajustamento se mostrou razoável, considerando-se a não utilização de sensores externos e de pontos de apoio. / Abstract: Under certain conditions the positioning and orientation sensors such as INS and GPS of a land-based mobile mapping system may fail for a certain time interval. The consequence is that the images captured during this time interval may be misoriented or even may have no orientation. This thesis proposes a solution to orient the images based only on image processing and a photogrammetric technique without any external sensors in order to overcome the lack of external orientation. A land-based mobile mapping system with a pair of video cameras and a GPS receiver was used to test the proposed methodology on an urban flat road. The video cameras were mounted on the roof of the vehicle with both optical axes parallel to the main road axis (Y). The methodology is based on the velocity estimation of the vehicle, which is done in two steps. Initially, the dense optical flow is computed then the velocity estimation is obtained through a filtering strategy that consists of using radial vectors in the low parts of the images. These radial vectors are detected by the Canny algorithm. The vehicle velocity is re-estimated after eliminating the optical flow outliers. With the reestimated velocity and with the video sampling time the spatial displacement of each image (with respect to the previous one of the sequence) is determined. The results show that the estimated velocity is pretty close to the true one and the quality of the least square adjustment is quite acceptable, considering that no external sensors were used. / Orientador: João Fernando Custódio da Silva / Coorientador: Messias Meneguette Júnior / Banca: Aluir Porfírio Dal Poz / Banca: Antonio Maria Garcia Tommaselli / Banca: Valentin Obac Roda / Banca: Almir Olivette Artero / Doutor
20

Testování přesnosti mobilní fotogrammetrie / Accuracy testing of mobile photogrammetry

Otrusinová, Jana January 2020 (has links)
This diploma thesis deals with a construction of a calibration field in the area of the AdMaS research centre (Brno University of Technology). Furthermore, photogrammetric data from the Riegl VMX-450 mobile mapping system has been acquired and processed. Selected points of the calibration field were used as control points. The other points of the calibration field were used as check points. As part of the testing, the coordinate deviations at the check points were assessed. The difference between the accuracy of mobile laser scanning and mobile photogrammetry was also evaluated. Coordinate deviations of mobile photogrammetry were tested according to standard ČSN 01 3410. Furthermore, a point cloud and a textured 3D model were generated.

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