Vision-based Real-Time Aerial Object Localization and Tracking for UAV Sensing System

The paper focuses on the problem of vision-based obstacle detection and tracking for unmanned aerial vehicle navigation. A real-time object localization and tracking strategy from monocular image sequences is developed by effectively integrating the object detection and tracking into a dynamic Kalman model. At the detection stage, the object of interest is automatically detected and localized from a saliency map computed via the image background connectivity cue at each frame; at the tracking stage, a Kalman filter is employed to provide a coarse prediction of the object state, which is further refined via a local detector incorporating the saliency map and the temporal information between two consecutive frames. Compared to existing methods, the proposed approach does not require any manual initialization for tracking, runs much faster than the state-of-the-art trackers of its kind, and achieves competitive tracking performance on a large number of image sequences. Extensive experiments demonstrate the effectiveness and superior performance of the proposed approach.Comment: 8 pages, 7 figure

Edge Detection by Adaptive Splitting II. The Three-Dimensional Case

In Llanas and Lantarón, J. Sci. Comput. 46, 485–518 (2011) we proposed an algorithm (EDAS-d) to approximate the jump discontinuity set of functions defined on subsets of ℝ d . This procedure is based on adaptive splitting of the domain of the function guided by the value of an average integral. The above study was limited to the 1D and 2D versions of the algorithm. In this paper we address the three-dimensional problem. We prove an integral inequality (in the case d=3) which constitutes the basis of EDAS-3. We have performed detailed computational experiments demonstrating effective edge detection in 3D function models with different interface topologies. EDAS-1 and EDAS-2 appealing properties are extensible to the 3D cas

Aproximación a la reconstrucción volumétrica en entorno virtual a través del uso de software libre

En esta investigación queremos mostrar el trabajo de restauración virtual realizado por medio de una combinación correcta de programas de software libre. Programas no orientados hacia la restauración en su forma primigenia. La interconexión correcta de estos programas crea una herramienta global que nos permite adaptarla a la restauración. Queremos demostrar que con el software elegido y un equipo de documentación asequible, se puede llegar a la reconstrucción de los faltantes de una obra escultórica, en un entorno virtual. Entendiendo que la reconstrucción en 3D es una forma no invasiva y eficaz de obtener una visión final de la obra restaurada. Las técnicas tradicionales lejos de estar desfasadas pueden ayudar e implementarse a las nuevas tecnologías por eso en este trabajo, nos hemos ayudado del dibujo y la fotografía para ampliar la información sobre la obra, este punto nos será de gran ayuda a la hora de trabajar con los programas de software elegidos. Para esta demostración se ha escogido el busto de un cristo del siglo XVIII, una escultura que se adapta perfectamente a nuestras necesidades a la hora de mostrar la restauración tridimensional pues es una obra incompleta en la mayoría de su conjunto.Agradecer la cesión de la obra con la que hemos trabajado a Jesús Montoliu Benita, vecino de la localidad de Paterna. Agradecer también el asesoramiento de Nelvys Mendoza Gurdián, investigadora y jurista de la Universidad de la Habana, Cuba. También mostrar mi gratitud a la Universitat Politècnica de ValènciaMontoliu Bautista, JE.; Madrid García, JA.; Grafiá Sales, JV. (2017). Aproximación a la reconstrucción volumétrica en entorno virtual a través del uso de software libre. Arché. (11 - 12):131-138. http://hdl.handle.net/10251/10128713113811 - 1

Avaliação do desempenho da técnica structure from motion para mapeamento de corredores

Orientador: Prof. Dr. Edson Aparecido MitishitaDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências da Terra, Programa de Pós-Graduação em Ciências Geodésicas. Defesa : Curitiba, 13/07/2020Inclui referências: p. 96-99Resumo: Os Veículos Aéreos não Tripulados têm se tornado cada vez mais presentes no contexto civil, sendo utilizados em diversas áreas do conhecimento. Aliados às técnicas de processamento de dados fotogramétricos e às novas abordagens desenvolvidas pela Visão Computacional, promoveram produtividade, economia e confiabilidade no processo de geração de produtos cartográficos em grandes escalas, através do alto nível de automatização proporcionada. Por este motivo, a técnica Structure from Motion, que tem seu funcionamento básico baseado na estereoscopia fotogramétrica, se tornou popular nas comunidades profissionais e científicas e atualmente é amplamente utilizada para fins de mapeamento. Desta forma, foram elaborados diversos estudos com o objetivo de determinar as melhores práticas, planejamento de voo e distribuição de pontos de apoio a utilizar para alcançar melhores exatidões no emprego do SfM, contudo a maioria destes estudos têm foco na geometria de um bloco de imagens e pouco se discute sobre a aplicação do SfM em projetos de engenharia que assumem a forma de um corredor, tais como rios, estradas, ferrovias e linhas de força. Sabendo que corredores apresentam fragilidades geométricas, torna-se importante a realização de estudos que buscam determinar as melhores práticas para o alcance de melhor exatidão no mapeamento de corredores. Neste contexto o objetivo deste trabalho é desenvolver um estudo teórico e propor procedimentos práticos para a realização de levantamentos aerofotogramétricos com o uso de faixas longas, processadas com aplicação da técnica SfM-MVS, utilizando um software especialista. Adicionalmente, os resultados obtidos serão comparados com resultados provenientes de programas de aerotriangulação. O corredor mapeado neste estudo possui aproximadamente 1,3 km de extensão e utilizou-se o recobrimento fotogramétrico de 80% de sobreposição longitudinal e 60% de sobreposição lateral, a uma altura de voo de aproximadamente 100 m. Três faixas foram adquiridas para verificar a influência da adição de faixas na exatidão e precisão alcançados. As coordenadas dos pontos de apoio foram extraídas do ortomosaico disponibilizado pelo projeto UFPR CampusMap. A análise da precisão e exatidão alcançada pelo processamento se dá através dos valores de erro médio quadrático dos resíduos dos pontos de apoio e das discrepâncias dos pontos de verificação, segundo a tolerância estabelecida neste estudo. Os resultados revelaram que, para o corredor estudado, alcança-se melhor exatidão quando pontos de apoio são inseridos a cada cinco bases. Além disso, a adição de faixas não proporciona redução significativa do valor do EQM das discrepâncias planialtimétricas dos pontos de verificação, sendo o mais importante para a redução deste valor, a quantidade de pontos de apoio empregada no ajustamento. Palavras-chaves: SfM. Corredor. Metashape. LPS.Abstract: Unmanned aerial vehicles have become increasingly present in the civil context, being used in several areas of knowledge. Combined with photogrammetric data processing techniques and new approaches developed by Computer Vision, they promoted productivity, economy, and reliability in the process of generating cartographic products. For this reason, the Structure from Motion technique, which has its basic function based on photogrammetric stereoscopy, has become popular in professional and scientific communities and is now widely used for mapping purposes. In this way, several studies were developed to determine the best practices, flight planning and distribution of support points to be used to achieve better accuracy in the use of the SfM, however, most of these studies focus on the geometry of a block of images and little is discussed about the application of SfM in engineering projects that take the form of a corridor, such as rivers, roads, railways, and power lines. Knowing that corridors have geometric weaknesses, it is important to carry out studies that seek to determine the best practices to achieve the best accuracy in corridor mapping. In this context the objective of this work is to develop a theoretical study and propose practical procedures for conducting aerophotogrammetric surveys using long strips, processed using the SfM-MVS technique, using specialist software. Additionally, the results obtained will be compared with results from conventional aerotriangulation programs. The corridor mapped in this study is approximately 1.3 km long and the photogrammetric covering of 80% longitudinal overlap and 60% lateral overlap was used, at a flight height of approximately 100 m. Three bands were acquired to verify the influence of the addition of bands on the accuracy and precision achieved. The coordinates of the support points were extracted from the orthomosaic provided by the UFPR CampusMap project. The analysis of the precision and accuracy achieved by the processing takes place through the values of Mean Square Error (MSE) of the residuals of the support points and the discrepancies of the verification points, according to the tolerance established in this study. The results revealed that, for the studied corridor, better accuracy is achieved when support points are inserted every five bases. Also, the addition of bands does not provide a significant reduction in the MSE value of the planialtimetric discrepancies of the verification points, the most important for the reduction of this value, the number of ground control points used in the adjustment. Key-words: SfM. Corridor. Metashape. LPS

Robust and Accurate Structure from Motion of Rigid and Nonrigid Objects

As a central theme in computer vision, the problem of 3D structure and motion recovery from image sequences has been widely studied during the past three decades, and considerable progress has been made in theory, as well as in prac- tice. However, there are still several challenges remaining, including algorithm robustness and accuracy, especially for nonrigid modeling. The thesis focuses on solving these challenges and several new robust and accurate algorithms have been proposed. The first part of the thesis reviews the state-of-the-art techniques of structure and motion factorization. First, an introduction of structure from motion and some mathematical background of the technique is presented. Then, the general idea and different formulations of structure from motion for rigid and nonrigid objects are discussed. The second part covers the proposed quasi-perspective projection model and its application to structure and motion factorization. Previous algorithms are based on either a simplified affine assumption or a complicated full perspective projection model. The affine model is widely adopted due to its simplicity, whereas the extension to full perspective suffers from recovering projective depths. A quasi-perspective model is proposed to fill the gap between the two models. It is more accurate than the affine model from both theoretical analysis and experimental studies. More geometric properties of the model are investigated in the context of one- and two-view geometry. Finally, the model was applied to structure from motion and a framework of rigid and nonrigid factorization under quasi-perspective assumption is established. The last part of the thesis is focused on the robustness and three new al- gorithms are proposed. First, a spatial-and-temporal-weighted factorization algorithm is proposed to handle significant image noise, where the uncertainty of image measurement is estimated from a new perspective by virtue of repro- jection residuals. Second, a rank-4 affine factorization algorithm is proposed to avoid the difficulty of image alignment with erroneous data, followed by a robust factorization scheme that can work with missing and outlying data. Third, the robust algorithm is extended to nonrigid scenarios and a new augmented nonrigid factorization algorithm is proposed to handle imperfect tracking data. The main contributions of the thesis are as follows: The proposed quasi- perspective projection model fills the gap between the simplicity of the affine model and the accuracy of the perspective model. Its application to structure and motion factorization greatly increases the efficiency and accuracy of the algorithm. The proposed robust algorithms do not require prior information of image measurement and greatly improve the overall accuracy and robustness of previous approaches. Moreover, the algorithms can also be applied directly to structure from motion of nonrigid objects