O uso de sistemas de assistência ao motorista (DAS) baseados em visão tem contribuído consideravelmente na redução de acidentes e consequentemente no auxílio de uma melhor condução. Estes sistemas utilizam basicamente uma câmera de vídeo embarcada (normalmente fixada no para-brisa) com o propósito de extrair informações acerca da rodovia e ajudar o condutor num melhor processo de dirigibilidade. Pequenas distrações ou a perda de concentração podem ser suficientes para que um acidente ocorra. Este trabalho apresenta uma proposta para o desenvolvimento de algoritmos para extrair informações sobre a sinalização em rodovias. Mais precisamente, serão abordados algoritmos de calibração de câmera explorando a geometria da pista, de extração da marcação de pintura (sinalização horizontal) e detecção e identificação de placas de trânsito (sinalização vertical). Os resultados experimentais indicam que o método de calibração de câmera alcançou bons resultados na obtenção dos parâmetros extrínsecos com erros inferiores a 0:5 . O erro médio encontrado nos experimentos com relação a estimativa da altura da câmera foi em torno de 12 cm (erro relativo aproximado de 10%), permitindo explorar o uso da realidade aumentada como uma possível aplicação. A acurácia global para a detecção e reconhecimento da sinalização horizontal (marcas seccionadas, contínuas e mistas) foi acima de 96% perante uma diversidade de situações apresentadas, tais como: sombras, variação de iluminação, degradação do asfalto e pintura. O uso da câmera calibrada para a detecção da sinalização vertical contribui para delimitar o espaço de varredura da janela deslizante do detector, bem como realizar a procura por placas em uma única escala para cada região de busca, caracterizada pela distância ao veículo. Os resultados apresentados reportam uma taxa global de classificação de aproximadamente 99% para o sinal de proibido ultrapassar, considerando-se uma base de dados limitada a 962 amostras. / The use of driver assistance systems (DAS) based on computer vision has helped considerably in reducing accidents and consequently aid in better driving. These systems primarily use an embedded video camera (usually fixed on the windshield) for the purpose of extracting information about the highway and assisting the driver in a better handling process. Small distractions or loss of concentration may be sufficient for an accident to occur. This work presents the development of algorithms to extract information about traffic signs on highways. More specifically, this work will tackle a camera calibration algorithm that exploits the geometry of the road track, algorithms for the extraction of road marking paint (lane markings) and detection and identification of vertical traffic signs. Experimental results indicate that the proposed method for obtaining the extrinsic parameters achieve good results with errors of less than 0:5 . The average error in our experiments, related to the camera height, were around 12 cm (relative error around 10%). Global accuracy for the detection and classification of road lane markings (dashed, solid, dashed-solid, solid-dashed or double solid) were over 96%. Finally, our camera calibration algorithm was used to reduce the search region and to define the scale of a slidingwindow detector for vertical traffic signs. The use of the calibrated camera for the detection of traffic signs contributes to define the scanning area of the sliding window and perform a search for signs on a unique scale for each region of interest, determined by the distance to the vehicle. The results reported a global classification rate of approximately 99% for the no overtaking sign, considering a limited of 962 samples.

O uso de sistemas de assistência ao motorista (DAS) baseados em visão tem contribuído consideravelmente na redução de acidentes e consequentemente no auxílio de uma melhor condução. Estes sistemas utilizam basicamente uma câmera de vídeo embarcada (normalmente fixada no para-brisa) com o propósito de extrair informações acerca da rodovia e ajudar o condutor num melhor processo de dirigibilidade. Pequenas distrações ou a perda de concentração podem ser suficientes para que um acidente ocorra. Este trabalho apresenta uma proposta para o desenvolvimento de algoritmos para extrair informações sobre a sinalização em rodovias. Mais precisamente, serão abordados algoritmos de calibração de câmera explorando a geometria da pista, de extração da marcação de pintura (sinalização horizontal) e detecção e identificação de placas de trânsito (sinalização vertical). Os resultados experimentais indicam que o método de calibração de câmera alcançou bons resultados na obtenção dos parâmetros extrínsecos com erros inferiores a 0:5 . O erro médio encontrado nos experimentos com relação a estimativa da altura da câmera foi em torno de 12 cm (erro relativo aproximado de 10%), permitindo explorar o uso da realidade aumentada como uma possível aplicação. A acurácia global para a detecção e reconhecimento da sinalização horizontal (marcas seccionadas, contínuas e mistas) foi acima de 96% perante uma diversidade de situações apresentadas, tais como: sombras, variação de iluminação, degradação do asfalto e pintura. O uso da câmera calibrada para a detecção da sinalização vertical contribui para delimitar o espaço de varredura da janela deslizante do detector, bem como realizar a procura por placas em uma única escala para cada região de busca, caracterizada pela distância ao veículo. Os resultados apresentados reportam uma taxa global de classificação de aproximadamente 99% para o sinal de proibido ultrapassar, considerando-se uma base de dados limitada a 962 amostras. / The use of driver assistance systems (DAS) based on computer vision has helped considerably in reducing accidents and consequently aid in better driving. These systems primarily use an embedded video camera (usually fixed on the windshield) for the purpose of extracting information about the highway and assisting the driver in a better handling process. Small distractions or loss of concentration may be sufficient for an accident to occur. This work presents the development of algorithms to extract information about traffic signs on highways. More specifically, this work will tackle a camera calibration algorithm that exploits the geometry of the road track, algorithms for the extraction of road marking paint (lane markings) and detection and identification of vertical traffic signs. Experimental results indicate that the proposed method for obtaining the extrinsic parameters achieve good results with errors of less than 0:5 . The average error in our experiments, related to the camera height, were around 12 cm (relative error around 10%). Global accuracy for the detection and classification of road lane markings (dashed, solid, dashed-solid, solid-dashed or double solid) were over 96%. Finally, our camera calibration algorithm was used to reduce the search region and to define the scale of a slidingwindow detector for vertical traffic signs. The use of the calibrated camera for the detection of traffic signs contributes to define the scanning area of the sliding window and perform a search for signs on a unique scale for each region of interest, determined by the distance to the vehicle. The results reported a global classification rate of approximately 99% for the no overtaking sign, considering a limited of 962 samples.

O uso de sistemas de assistência ao motorista (DAS) baseados em visão tem contribuído consideravelmente na redução de acidentes e consequentemente no auxílio de uma melhor condução. Estes sistemas utilizam basicamente uma câmera de vídeo embarcada (normalmente fixada no para-brisa) com o propósito de extrair informações acerca da rodovia e ajudar o condutor num melhor processo de dirigibilidade. Pequenas distrações ou a perda de concentração podem ser suficientes para que um acidente ocorra. Este trabalho apresenta uma proposta para o desenvolvimento de algoritmos para extrair informações sobre a sinalização em rodovias. Mais precisamente, serão abordados algoritmos de calibração de câmera explorando a geometria da pista, de extração da marcação de pintura (sinalização horizontal) e detecção e identificação de placas de trânsito (sinalização vertical). Os resultados experimentais indicam que o método de calibração de câmera alcançou bons resultados na obtenção dos parâmetros extrínsecos com erros inferiores a 0:5 . O erro médio encontrado nos experimentos com relação a estimativa da altura da câmera foi em torno de 12 cm (erro relativo aproximado de 10%), permitindo explorar o uso da realidade aumentada como uma possível aplicação. A acurácia global para a detecção e reconhecimento da sinalização horizontal (marcas seccionadas, contínuas e mistas) foi acima de 96% perante uma diversidade de situações apresentadas, tais como: sombras, variação de iluminação, degradação do asfalto e pintura. O uso da câmera calibrada para a detecção da sinalização vertical contribui para delimitar o espaço de varredura da janela deslizante do detector, bem como realizar a procura por placas em uma única escala para cada região de busca, caracterizada pela distância ao veículo. Os resultados apresentados reportam uma taxa global de classificação de aproximadamente 99% para o sinal de proibido ultrapassar, considerando-se uma base de dados limitada a 962 amostras. / The use of driver assistance systems (DAS) based on computer vision has helped considerably in reducing accidents and consequently aid in better driving. These systems primarily use an embedded video camera (usually fixed on the windshield) for the purpose of extracting information about the highway and assisting the driver in a better handling process. Small distractions or loss of concentration may be sufficient for an accident to occur. This work presents the development of algorithms to extract information about traffic signs on highways. More specifically, this work will tackle a camera calibration algorithm that exploits the geometry of the road track, algorithms for the extraction of road marking paint (lane markings) and detection and identification of vertical traffic signs. Experimental results indicate that the proposed method for obtaining the extrinsic parameters achieve good results with errors of less than 0:5 . The average error in our experiments, related to the camera height, were around 12 cm (relative error around 10%). Global accuracy for the detection and classification of road lane markings (dashed, solid, dashed-solid, solid-dashed or double solid) were over 96%. Finally, our camera calibration algorithm was used to reduce the search region and to define the scale of a slidingwindow detector for vertical traffic signs. The use of the calibrated camera for the detection of traffic signs contributes to define the scanning area of the sliding window and perform a search for signs on a unique scale for each region of interest, determined by the distance to the vehicle. The results reported a global classification rate of approximately 99% for the no overtaking sign, considering a limited of 962 samples.

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2015-11-26T10:24:30Z No. of bitstreams: 2 Dissertação - Leomar Rufino Alves Júnior - 2015.pdf: 5358486 bytes, checksum: 65b930c6a83152c4867b2f00eb5865b2 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-11-27T07:27:21Z (GMT) No. of bitstreams: 2 Dissertação - Leomar Rufino Alves Júnior - 2015.pdf: 5358486 bytes, checksum: 65b930c6a83152c4867b2f00eb5865b2 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-11-27T07:27:21Z (GMT). No. of bitstreams: 2 Dissertação - Leomar Rufino Alves Júnior - 2015.pdf: 5358486 bytes, checksum: 65b930c6a83152c4867b2f00eb5865b2 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-03-13 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / This research aimed to verify the precision and accuracy of orthomosaics and Digital Surface Model (DSM) generated automatically by aerial photography taken with an Unmanned Aerial Vehicle (UAV) in urban and rural areas at the cities of Goiânia, Goiás and Edéia, all located in the state of Goiás. The survey also verified for the influence of the scale, depending on the flight height, the influence of the sunlight, and the phenological analysis obtained in agricultural areas with sugarcane and corn (vegetative cycle) crops. Flight plans were drawn up in E-mo-tion software provided by Sensefly - Swiss company manufacturer of UAV Swinglet CAM used in this work. The camera on board UAV was the Canon IXUS 220 HS, with a spatial resolution of 12.1 megapixel, CMOS sensor equipped with type 1 / 2.3" (4000 x 3000 pixel), pixel pitch of 1.54 m, and focal distance equivalent of 35 mm. To check the precision and accuracy of orthomosaics in urban areas, the flights were uniformly distributed in the study area with three-dimensional coordinates pre-marked targets read in the orthomosaic itself, and compared with the coordinates obtained by RTK and static fast positioning methods geodetic survey, using a pair of GNSS signal receiver. Evaluation of Cartographic Accuracy Standards (PEC, defined by the Brazilian decree, no. 89817 of June 20, 1984) was performed by discrepancies between these coordinates. The bias was analyzed by student's t test and the accuracy with the chi-square probability. We have found that in those orthomosaics performed over the urban area in Goiânia city, some buildings were not properly processed in terms of the conical to orthogonal projection; this product was classified as PEC Class A to the 1/250 scale. In Goiás city, the generated orthomosaics without support points were classified as PEC Class A to the 1/2,500 scale, while the orthomosaic generated with eight supporting points was classified as PEC Class A to the 1/1,125 scale. The orthomosaic and MDS generated without ground supporting points presented planialtimetric trends. The mean difference calculated in the orthomosaic with ground supporting was 54 times lower on the E axis, and 111 times lower in N axis, and 10 times lower in the Z axis relative to the average of the discrepancies in orthomosaic without ground control points. The MDS generated with and without supporting showed vertical displacement trend. Thus it was evident the need for supporting points for making orthomosaics and MDS obtained with UAV. In flights performed in crop areas, it was observed that for a better estimate of MPRI vegetation index, the photographs needs to with larger scales (GSD of 5 cm), even with a higher software difficulty in finding homologous points. It did not occur when we used pictures with smaller scales (GSD 20 cm, or larger) for the generation of orthomosaics and MDS. / Esta pesquisa teve por objetivo verificar a precisão e acurácia dos ortomosaicos e Modelo Digital de Superfície (MDS) gerados automaticamente por programa de aerofotogrametria, utilizando fotografias aéreas tomadas com um Veículo Aéreo Não Tripulado (VANT) em áreas urbanas e rurais das cidades de Goiânia, Goiás e Edéia, todas no estado de Goiás. A pesquisa também verificou a influência da escala, em função da altura de voo, a influência da iluminação solar e a análise fenológica em ortomosaicos obtidos em áreas agrícolas com cultivo de cana-de-açúcar e milho (clico vegetativo). Os planos de voo foram elaborados no programa E-mo-tion, fornecido pela Sensefly – empresa suíça fabricante do VANT Swinglet CAM utilizado nesse trabalho. A câmara instalada no VANT foi a Canon IXUS 220 HS, com resolução espacial de 12,1 megapixel, equipada com sensor tipo CMOS 1/2,3” (4000 x 3000 pixel), pixel pitch de 1,54 m, e distância focal equivalente de 35 mm. Para verificar a precisão e acurácia dos ortomosaicos, nas áreas urbanas, foram uniformemente distribuídos nas áreas de estudo alvos pré-sinalizados, com coordenadas tridimensionais lidas nos ortomosaicos e comparadas com as coordenadas obtidas por levantamento geodésico nos métodos de posicionamento RTK e estático rápido, utilizando-se um par de receptor de sinais GNSS. A avaliação do Padrão de Exatidão Cartográfica (PEC) foi realizada pelas discrepâncias entre essas coordenadas. A tendenciosidade foi analisada pelo teste t de Student e a precisão pela probabilidade do qui-quadrado, considerando o ortomosaico Classe A conforme PEC estabelecido no Decreto nº 89.817 de 20.06.1984. Verificou-se que nos ortomosaicos oriundos do aerolevantamento realizado na área urbana (Goiânia), algumas edificações não foram devidamente transformadas da projeção cônica para a ortogonal. Os ortomosaicos gerados com mais de 8 pontos de controle foram classificados como Classe A para a escala de 1/250. Verificou-se, também, que o ortomosaico sem pontos de apoio, oriundo dos aerolevantamentos realizados na cidade de Goiás, foi classificado como Classe A na escala 1/2.500, enquanto o ortomosaico gerado com oito pontos de apoio foi classificado como Classe A na escala de 1/1.125, conforme parâmetros de precisão e exatidão estabelecidos por este mesmo Decreto Federal. O ortomosaico e MDS gerados sem pontos de apoio apresentaram tendência planialtimétrica. As médias das discrepâncias calculadas no ortomosaico com apoio foi 54 vezes menor no eixo E, 111 vezes menor no eixo N e 10 vezes menor no eixo Z, em relação à média das discrepâncias no ortomosaico sem pontos de apoio. O MDS gerado com e sem apoio apresentaram tendência de deslocamento vertical. Ficou evidente a necessidade de utilizar pontos de apoio para a confecção de ortomosaicos e MDS obtidos com VANT. Em relação aos voos realizados em áreas de cultivo observou-se que para uma melhor estimativa do MPRI observou-se que na geração de ortomosaicos a partir de fotografias com escalas maiores (GSD de 5 cm), o programa de processamento das fotografias teve dificuldade em encontrar os pontos homólogos necessários à geração dos ortomosaicos. Fato que não ocorreu quando se utilizou fotografias com escalas menores (GSD de 20 cm) para a geração dos ortomosaicos e MDS.

Made available in DSpace on 2016-08-17T14:53:12Z (GMT). No. of bitstreams: 1 Irlandino Almeida.pdf: 795180 bytes, checksum: 9f8896e26b58665bad7d75b665940404 (MD5) Previous issue date: 2007-09-17 / We present a semi-automatic methodology for three-dimensional reconstruction using an image-based modeling environment. This is done through an initial camera calibration step that makes possible to the viewer, identify objects in the 2D acquired image and them get its position from the camera parameters. This methodology can be applied in the real word model reconstruction like electric and industry installations. / Apresentamos uma metodologia semi-automática para reconstrução tridimensional utilizando um ambiente de modelagem no qual o usuário, a partir de uma determinada imagem e de pontos nela selecionados com seu correspondente no espaço do mundo, realiza a calibração da câmera. Após este processo, a cena poderá ser composta a partir de objetos pré-estabelecidos fornecidos pelo ambiente de modelagem tridimensional baseado na imagem. Esta metodologia pode ser aplicada na reconstrução de modelos do mundo real, como instalações elétricas e industriais.

Orientador:Ricardo Machado Leite de Barros / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Educação Física / Made available in DSpace on 2018-08-21T23:09:57Z (GMT). No. of bitstreams: 1 Silvatti_AmandaPiaia_D.pdf: 2153043 bytes, checksum: bfa39ebf2fe3e82ab53b434c5a4e6d8a (MD5) Previous issue date: 2013 / Resumo: Para análises subaquáticas de movimentos tridimensionais é necessária uma calibração precisa de grandes volumes. Métodos baseados em modelos lineares de câmeras são comumente utilizados na biomecânica e para isso faz-se necessário a construção, o transporte e a medição de estruturas rígidas, o que se torna mais difícil quando volumes maiores estão envolvidos. Recentemente, métodos alternativos baseados em modelos não-lineares de câmeras, foram propostos para resolver este aspecto. Assim, os objetivos deste trabalho foram 1) avaliar a exatidão da reconstrução tridimensional fora e dentro da água utilizando o método proposto por Zhang (2000); 2) avaliar a exatidão dos métodos não-lineares para a calibração de câmeras propostos por Hatze, 1988, Cerveri, et al., 1998 e Zhang, 2000 para aplicações com câmeras submersas e os efeitos da variação da posição no volume de calibração sobre a exatidão de reconstrução tridimensional dos métodos e ressaltando, ainda as vantagens e desvantagens de cada método e 3) testar a aplicabilidade dos métodos não-lineares propostos por Cerveri et al., 1998 e Zhang, 2000 para a reconstrução da trajetória da mão de nadadores em diferentes nados. Para aquisição dos dados foi utilizado um sistema de análise cinemática (DVideo), que foi adaptado para aquisição de imagens submersa. O sistema consiste de computadores ligados em câmeras (Basler) para aquisição online de dados. Caixa-estanques especialmente desenvolvidas para o modelos das câmeras foram utilizadas para proteção e um genlocker trigger foi utilizado para a sincronização das câmeras. Tripés para sustentação e fixação das câmeras foram adaptados com ventosas para fixação no fundo da piscina. Para a correção da distorção foram implementados em Matlab os métodos não-lineares para a calibração de câmeras. Um teste de barra rígida foi usado para avaliação da exatidão e precisão. Os resultados mostraram que os métodos propostos por Cerveri et al., 1998 (1,16mm a 0,96mm) e Zhang, 2000 (0,73mm) são alternativas promissoras para análise tridimensional de movimentos subaquáticos. Ambas as metodologias apresentaram resultados com maior exatidão que os encontrados na literatura. Este fato ocorreu devido a uma melhor modelagem da distorção óptica que foi confirmada pela menor influência no erro relativo à posição do objeto no volume de aquisição. Quanto à flexibilidade e portabilidade em relação ao objeto de calibração, ambos os métodos usam objetos mais fáceis de construir e manipular do que os objetos tradicionalmente utilizados. O sistema para a análise tridimensional do movimento utilizando câmeras submersas mostrou-se ser adequado para aplicações subaquáticas. Uma vez que, os resultados aqui relatados podem ser imediatamente apreciados pelos treinadores, pois foi possível identificar simetria ou assimetria entre os dois lados, a variabilidade intra e inter-sujeitos em termos de padrões de movimento e concordância ou discordância com o modelo teórico. Importante ressaltar que existe a possibilidade de extensão da análise para os diferentes segmentos corporais e o sistema e os métodos para a calibração de câmeras apresentados neste trabalho podem ser utilizado para qualquer esporte ou atividade realizada na água, como por exemplo, hidroginásticas ou práticas de reabilitação / Abstract: In order to perform a three-dimensional motion analysis in underwater conditions is necessary to calibrate accurately large volumes. Methods based on linear camera models are commonly used in biomechanics and this requires to construct, to transport and to measurement rigid structures, which becomes more difficult when larger volumes are involved. Recently, alternative methods based on nonlinear camera models have been proposed to address this aspect. The aims of this study were 1) to evaluate the accuracy of 3D reconstruction out and underwater using the method proposed by Zhang (2000); 2) to evaluate the accuracy of nonlinear camera calibration methods proposed by Hatze, 1988, Cerveri, et al., 1998 and Zhang, 2000 for underwater applications using submerged cameras and the effects of object position in the acquisition volume on the accuracy of 3D reconstruction methods, highlighting the advantages and disadvantages of each method, and 3) to test the applicability of the nonlinear methods proposed by Cerveri et al., 1998 and Zhang, 2000 for the reconstruction of the swimmers hand trajectory in different swims styles. For data acquisition, we used a kinematic analysis system (DVideo), which was adapted for underwater conditions. The system consists of cameras (Basler) connected in computers for online data acquisition. Waterproof housings were specially designed to protect the cameras and a genlocker trigger was used to synchronize the cameras. Tripods to support and to fix the cameras were adapted with suction cups and were used to fix them on the swimming pool floor. In order to perform the distortion correction the nonlinear camera calibration methods were implemented in Matlab software. A rigid bar test was used to assess the accuracy and precision. The results showed that the methods proposed by Cerveri et al. 1 998 (1.16 mm to 0.96 mm) and Zhang, 2000 (0.73 mm) are promising alternatives for 3D underwater motion analysis. Both methodologies presented results with greater accuracy than those found in the literature. This occurred due to an improvement of the distortion modeling and that was confirmed by the smallest influence of the object position on the error values. Related to the flexibility and portability of the calibration object, both methods use objects easier to build and manipulate than the objects traditionally used. The 3D motion analysis system using submerged cameras showed to be suitable for underwater applications. The results reported here can be immediately appreciated by coaches, because it was possible to identify symmetry or asymmetry between the two sides, the variability within and between subjects in terms of movement patterns and agreement or disagreement with the theoretical model. Important to emphasize that there is the possibility of extending the analysis for different body segments and the system and the camera calibration methods presented in this work can be used for any sport or activity performed in water, such as hydro gymnastic or rehabilitation practices / Doutorado / Biodinamica do Movimento Humano / Doutor em Educação Física

Abstract Three-dimensional scene reconstruction has been an important area of research for many decades. It has a myriad of applications ranging from entertainment to medicine. This thesis explores the 3D reconstruction pipeline and proposes novel methods to improve many of the steps necessary to achieve a high quality reconstruction. It proposes novel methods in the areas of depth sensor calibration, simultaneous localization and mapping, depth map inpainting, point cloud simplification, and free-viewpoint rendering. Geometric camera calibration is necessary in every 3D reconstruction pipeline. This thesis focuses on the calibration of depth sensors. It presents a review of sensors models and how they can be calibrated. It then examines the case of the well-known Kinect sensor and proposes a novel calibration method using only planar targets. Reconstructing a scene using only color cameras entails di_erent challenges than when using depth sensors. Moreover, online applications require real-time response and must update the model as new frames are received. The thesis looks at these challenges and presents a novel simultaneous localization and mapping system using only color cameras. It adaptively triangulates points based on the detected baseline while still utilizing non-triangulated features for pose estimation. The thesis addresses the extrapolating missing information in depth maps. It presents three novel methods for depth map inpainting. The first utilizes random sampling to fit planes in the missing regions. The second method utilizes a 2nd-order prior aligned with intensity edges. The third method learns natural filters to apply a Markov random field on a joint intensity and depth prior. This thesis also looks at the issue of reducing the quantity of 3D information to a manageable size. It looks at how to merge depth maps from multiple views without storing redundant information. It presents a method to discard this redundant information while still maintaining the naturally variable resolution. Finally, transparency estimation is examined in the context of free-viewpoint rendering. A procedure to estimate transparency maps for the foreground layers of a multi-view scene is presented. The results obtained reinforce the need for a high accuracy 3D reconstruction pipeline including all the previously presented steps. / Tiivistelmä Kolmiuloitteisen ympäristöä kuvaavan mallin rakentaminen on ollut tärkeä tutkimuksen kohde jo usean vuosikymmenen ajan. Sen sovelluskohteet ulottuvat aina lääketieteestä viihdeteollisuuteen. Väitöskirja tarkastelee 3D ympäristöä kuvaavan mallin tuottamisprosessia ja esittää uusia keinoja parantaa korkealaatuisen rekonstruktion tuottamiseen vaadittavia vaiheita. Työssä esitetään uusia menetelmiä etäisyyssensoreiden kalibrointiin, samanaikaisesti tapahtuvaan paikannukseen ja kartoitukseen, syvyyskartan korjaamiseen, etäisyyspistepilven yksinkertaistamiseen ja vapaan katselukulman kuvantamiseen. Väitöskirjan ensi osa keskittyy etäisyyssensoreiden kalibrointiin. Työ esittelee erilaisia sensorimalleja ja niiden kalibrointia. Yleisen tarkastelun lisäksi keskitytään hyvin tunnetun Kinect-sensorin käyttämiseen, ja ehdotetaan uutta kalibrointitapaa pelkkiä tasokohteita hyväksikäyttäen. Pelkkien värikameroiden käyttäminen näkymän rekonstruointiin tuottaa erilaisia haasteita verrattuna etäisyyssensoreiden käyttöön kuvan muodostamisessa. Lisäksi verkkosovellukset vaativat reaaliaikaista vastetta. Väitös tarkastelee kyseisiä haasteita ja esittää uudenlaisen yhtäaikaisen paikannuksen ja kartoituksen mallin tuottamista pelkkiä värikameroita käyttämällä. Esitetty tapa kolmiomittaa adaptiivisesti pisteitä taustan pohjalta samalla kun hyödynnetään eikolmiomitattuja piirteitä asentotietoihin. Työssä esitellään kolme uudenlaista tapaa syvyyskartan korjaamiseen. Ensimmäinen tapa käyttää satunnaispisteitä tasojen kohdentamiseen puuttuvilla alueilla. Toinen tapa käyttää 2nd-order prior kohdistusta ja intensiteettireunoja. Kolmas tapa oppii filttereitä joita se soveltaa Markov satunnaiskenttiin yhteisillä tiheys ja syvyys ennakoinneilla. Tämä väitös selvittää myös mahdollisuuksia 3D-information määrän pienentämiseen käsiteltävälle tasolle. Työssä selvitetään, kuinka syvyyskarttoja voidaan yhdistää ilman päällekkäisen informaation tallentamista. Työssä esitetään tapa jolla päällekkäisestä datasta voidaan luopua kuitenkin säilyttäen luonnollisesti muuttuva resoluutio. Viimeksi, tutkimuksessa on esitetty läpinäkyvyyskarttojen arviointiproseduuri etualan kerroksien monikatselukulmanäkymissä vapaan katselukulman renderöinnin näkökulmasta. Saadut tulokset vahvistavat tarkan 3D-näkymän rakentamisliukuhihnan tarvetta sisältäen kaikki edellä mainitut vaiheet.

Measuring 3D surface geometry with precision and accuracy is an important part of many engineering and scientific tasks. 3D Scanning techniques measure surface geometry by estimating the locations of sampled surface points. In recent years, Structured-Light 3D scanners have gained significant popularity owing to their ability to produce highly accurate scans in real-time at a low cost. In this thesis we describe an approach for Structured-Light 3D scanning using a digital camera and a digital projector. We utilise the projective geometric relationships between the projector and the camera to carry out both an implicit calibration of the system and to solve for 3D structure. Our approach to geometric calibration is flexible, reliable and amenable to robust estimation. In addition, we model and account for the radiometric non-linearities in the projector such as gamma distortion. Finally, we apply a post-processing step to efficiently smooth out high-frequency surface noise while retaining the structural details. Consequently, the proposed work reduces the computational load and set-up time of a Structured-Light 3D scanner; thereby speeding up the whole scanning process while retaining the ability to generate highly accurate results. We demonstrate the accuracy of our scanning results on real-world objects of varying degrees of surface complexity. Introduction The projective geometry for a pair of pin-hole viewing devices is completely defined by their intrinsic calibration and their relative motion or extrinsic calibration in the form of matrices. For a Euclidean reconstruction, the geometry elements represented by the calibration matrices must be parameterised and estimated in some form. The use of a projector as the ‘second viewing’ device has led to numerous approaches to model and estimate its intrinsic parameters and relative motion with respect to the camera's 3D co-ordinate system. Proposed thesis work assimilates the benefits of projective geometry constructs such as Homography and the invariance of the cross-ratios to simplify the system calibration and the 3D estimation processes by an implicit modeling of the projector's intrinsic parameters and its relative motion. Though linear modeling of the projective geometry between a camera-projector view-pair captures the most essential aspects of the underlying geometry, it does not accommodate system non-linearities due to radiometric distortions of a projector device. We propose an approach that uses parametric splines to model the systematic errors introduced by radiometric non-linearities and thus correct for them. For 3D surfaces reconstructed as point-clouds, noise manifests itself as some high-frequency variations for the resulting mesh. Various pre and/or post processing techniques are proposed in the literature to model and minimize the effects of noise. We use simple bilateral filtering of the depth-map for the reconstructed surface to smoothen the surface while retaining its structural details. Modeling Projective Relations In our approach for calibrating the projective-geometric structure of a projector-camera view-pair, the frame of reference for measurements is attached to the camera. The camera is calibrated using a commonly used method. To calibrate the scanner system, one common approach is to project sinusoidal patterns onto the reference planes to generate reference phase maps. By relating the phase-information between the projector and image pixels, a dense mapping is obtained. However, this is an over-parameterisation of the calibration information. Since the reference object is a plane, we can use the projective relationships induced by a plane to implicitly calibrate the projector geometry. For the estimation of the three-dimensional structure of the imaged object, we utilise the invariance of cross-ratios along with the calibration information of two reference planes. Our formulation is also extensible to utilise more than two reference plane to compute more than one estimate of the location of an unknown surface point. Such estimates are amenable to statistical analysis which allows us to derive both the shape of an object and associate reliability scores to each estimated point location. Radiometric Correction Structured-light based 3D scanners commonly employ phase-shifted sinusoidal patterns to solve for the correspondence problem. For scanners using projective geometry between a camera and a projector, the projector's radiometric non-linearities introduce systematic errors in establishing correspondences. Such errors manifest as visual artifacts which become pronounced when fewer phase-shifted sinusoidal patterns are used. While these artifacts can be avoided by using a large number of phase-shifts, doing so also increases the acquisition time. We propose to model and rectify such systematic errors using parametric representations. Consequently, while some existing methods retain the complete reference phase maps to account for such distortions, our approach describes the deviations using a few model parameters. The proposed approach can be used to reduce the number of phase-shifted sinusoidal patterns required for codification while suppressing systematic artifacts. Additionally, our method avoids the 1D search steps that are needed when a complete reference phase map is used, thus reducing the computational load for 3D estimation. The effectiveness of our method is demonstrated with reconstruction of some geometric surfaces and a cultural figurine. Filtering Noise For a structured-light 3D scanner, various sources of noise in the environment and the devices lead to inaccuracies in estimating the codewords (phase map) for an unknown surface, during reconstruction. We examine the effects of such noise factors on our proposed methods for geometric and radiometric estimation. We present a quantitative evaluation for our proposed method by scanning the objects of known geometric properties or measures and then computing the deviations from the expected results. In addition, we evaluate the errors introduced due to inaccuracies in system calibration by computing the variance statistics from multiple estimates for the reconstructed 3D points, where each estimate is computed using a different pair of reference planes. Finally, we discuss the efficacy of certain filtering techniques in reducing the high-frequency surface noise when applied to: (a) the images of the unknown surface at a pre-processing stage, or (b) the respective phase (or depth) map at a post-processing stage. Conclusion In this thesis, we motivate the need for a procedurally simple and computationally less demanding approach for projector calibration. We present a method that uses homographies induced by a pair of reference planes to calibrate a structured-light scanner. By using the projective invariance of the cross-ratio, we solved for the 3D geometry of a scanned surface. We demonstrate the fact that 3D geometric information can be derived using our approach with accuracy on the order of 0.1 mm. Proposed method reduces the image acquisition time for calibration and the computational needs for 3D estimation. We demonstrate an approach to effectively model radiometric distortions for the projector using cubic splines. Our approach is shown to give significant improvement over the use of complete reference phase maps and its performance is comparable to that of a sate-of-the-art method, both quantitatively as well as qualitatively. In contrast with that method, proposed method is computationally less expensive, procedurally simpler and exhibits consistent performance even at relatively higher levels of noise in phase estimation. Finally, we use a simple bilateral filtering on the depth-map for the region-of-interest. Bilateral filtering provides the best trade-off between surface smoothing and the preservation of its structural details. Our filtering approach avoids computationally expensive surface normal estimation algorithms completely while improving surface fidelity.

At present, there are only a few systems in the world, that allow measurement of the dimensional accuracy of hot forgings directly in the manufacturing process. This work deals with the development of the calibration method of the cameras for the developed photogrammetric system, intended for the mentioned purposes. The conditions of measurement are very specific - high temperature and large dimensions of measured semi-finished products, environment of heavy industry. Employed methods are chosen with the emphasis on reliability of the system, taking into account the demanding conditions in the industrial premises. Calibration is designed for a large field of view, utilizing coded reference points in a scene with known spatial coordinates. The result of the work is the calibration software created in the MATLAB environment.

Stereo vision is one of the most popular elements in the field of mobile robots and significantly contributes to their autonomous behaviour. The aim of the diploma thesis was to design and implement a camera module as a hardware sensor input, which is independent, with the possibility of supplementing the system with other cameras, and to create a depth map from a pair of cameras. The diploma thesis consists of theoretical and practical part, including the conclusion of results. The theoretical part introduces the ROS framework, discusses methods of creating depth maps, and provides an overview of the most popular stereo cameras in robotics. The practical part describes in detail the preparation of the experiment and its implementation. It also describes the camera calibration and the depth map creating. The last chapter contains an evaluation of the experiment.