Examinando por Materia "Computer vision"
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Ítem Biomedical computer vision using computer algebra: Analysis of a case of rhinocerebral mucormycosis in a diabetic boy(Springer Science + Business Media, 2010-01-01) Vélez, M.; Ospina, J.; Vélez, M.; Ospina, J.; Universidad EAFIT. Departamento de Ciencias; Lógica y ComputaciónComputer algebra is applied to biomedical computer vision. Specifically certain biomedical images resulting from a case of rhinocerebral mucormysocis in a diabetic boy are analyzed using techniques in computational geometry and in algebraic-geometric topology. We apply convolution and deblurring via diffusion equation from the side of computational geometry and knot theory, graph theory and singular homology form the side of algebraic-geometric topology. Our strategy consists in to represent the biomedical images using algebraic structures in such way that the peculiarities of the images are represented using algebraic complexities. With our strategy we obtain an automatic procedure for the analysis and the diagnostic based on biomedical images. © 2010 Springer-Verlag Berlin Heidelberg.Ítem Cámaras IP: monitoreo virtual de proyectos de construcción(Universidad EAFIT, 2014) Acevedo Pino, Camilo Enrique; Botero Botero, Luis FernandoEl adecuado seguimiento a los proyectos en ejecución es necesario para el sector de la construcción, pues un ineficiente e inefectivo sistema de control del avance de actividades puede afectar la productividad, independiente del tamaño de los proyectos, tanto públicos como privados, ya que la gran mayoría de personal operativo, en ausencia de la adecuada supervisión, no realizan sus labores con el mismo rendimiento, afectando la productividad del proyecto en ejecución -- Adicionalmente, la cantidad de accidentes que se pueden prevenir con un correcto seguimiento y sus correspondientes ahorros, permiten evaluar alternativas de monitoreo y control por medio de tecnologías de información y comunicaciones -- Con el seguimiento virtual se puede mejorar la productividad, la seguridad industrial, optimizar la logística y tener seguimiento detallado de actividades de construcción -- El monitoreo virtual de proyectos mediante cámaras IP, ayuda a las diferentes áreas involucradas en la ejecución de proyectos de construcción -- Proporciona un seguimiento óptimo y preciso de las diferentes labores, detectando equipos inutilizados, condiciones de seguridad poco apropiadas o imprudencias de trabajadores que pueden generar accidentes -- Este método permite a cualquier persona autorizada revisar y controlar la obra de manera segura por medios virtuales remotos, proporcionando una óptima solución de control, al optimizar la movilidad del individuo sin tener que desplazarse a lugares alejadosÍtem Computational Geometry in Medical Applications(Universidad EAFIT, 2016) Cortés Acosta, Camilo Andrés; Ruíz Salguero, Óscar Eduardo; Flórez Esnal, JuliánÍtem Desarrollo de un algoritmo de corte de mallas tridimensionales en ambientes virtuales con aplicaciones en simuladores quirúrgicos(Universidad EAFIT, 2009) Peniche González, Amaury Andrés; Díaz León, Christian AndrésÍtem Descubriendo la distribución espacial de comercio en ciudades con economías informales(Universidad EAFIT, 2020) Saldarriaga Marín, Juan Camilo; Duque Cardona, Juan CarlosAn economic census aims to record economic activity in a city by collecting geo-referenced survey data. Although its benefits are significant, the costs are very high and, for this reason, it is very rare that the economic census information is up to date and complete. In this work we propose a new methodology to detect and georeference the visible commercial activity in a city or region in an efficient way, generating automated reports of visible commercial activity in a region of interest. This methodology tries to estimate the spatial distribution that allows having an economic census but only for visible commerce. We contrast the results of our methodology with official information from the Chamber of Commerce to estimate the spatial distribution of informal visible commerce or unregistered commerce in the municipality of Envigado.Ítem Edge and corner identification for tracking the line of sight(Fondo Editorial EAFIT, 2005) Orozco, María S.; Ruíz, Óscar E.; Jasnoch, Uwe; Kretschmer, Ursula; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEThis article presents an edge-corner detector, implemented in the realm of the GEIST project (an Computer Aided Touristic Information System) to extract the information of straight edges and their intersections (image corners) from camera-captured (real world) and computer-generated images (from the database of Historical Monuments, using observer position and orientation data) -- Camera and computer-generated images are processed for reduction of detail, skeletonization and corner-edge detection -- The corners surviving the detection and skeletonization process from both images are treated as landmarks and fed to a matching algorithm, which estimates the sampling errors which usually contaminate GPS and pose tracking data (fed to the computer-image generatator) -- In this manner, a closed loop control is implemented, by which the system converges to exact determination of position and orientation of an observer traversing a historical scenario (in this case the city of Heidelberg) -- With this exact position and orientation, in the GEIST project other modules are able to project history tales on the view field of the observer, which have the exact intended scenario (the real image seen by the observer) -- In this way, the tourist “sees” tales developing in actual, material historical sites of the city -- To achieve these goals this article presents the modification and articulation of algorithms such as the Canny Edge Detector, SUSAN Corner Detector, 1-D and 2-D filters, etceteraÍtem Evaluation of interest point detectors for image information extraction(2012) Barandiaran, Iñigo; Goenetxea, Jon; Congote, John; Graña, Manuel; Ruíz, Oscar; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEInterest points extraction and matching is a common task in many computer vision based application, which are used in different domains, such as 3D reconstruction, object recognition, or tracking -- We present an evaluation of current state of the art about interest point extraction algorithms to measure several parameters, such as detection quality, invariance to rotation and scale transformation, and computational efficiencyÍtem Evaluation of interest point detectors for image information extraction(IOS PRESS, 2012-01-01) Barandiaran, I.; Congote, J.; Goenetxea, J.; Ruiz, O.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEInterest points extraction and matching is a common task in many computer vision based application, which are used in different domains, such as 3D reconstruction, object recognition, or tracking. We present an evaluation of current state of the art about interest point extraction algorithms to measure several parameters, such as detection quality, invariance to rotation and scale transformation, and computational efficiency. © 2012 The authors and IOS Press. All rights reserved.Ítem Extending marching cubes with adaptative methods to obtain more accurate iso-surfaces(Springer Verlag, 2010-01-01) Congote, J.; Moreno, A.; Barandiaran, I.; Barandiaran, J.; Ruiz, O.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEThis work proposes an extension of the Marching Cubes algorithm, where the goal is to represent implicit functions with higher accuracy using the same grid size. The proposed algorithm displaces the vertices of the cubes iteratively until the stop condition is achieved. After each iteration, the difference between the implicit and the explicit representations is reduced, and when the algorithm finishes, the implicit surface representation using the modified cubical grid is more accurate, as the results shall confirm. The proposed algorithm corrects some topological problems that may appear in the discretization process using the original grid. © 2010 Springer-Verlag Berlin Heidelberg.Ítem Face reconstruction with structured light(INSTICC-INST SYST TECHNOLOGIES INFORMATION CONTROL & COMMUNICATION, 2011-01-01) Congote, J.; Barandiaran, I.; Barandiaran, J.; Nieto, M.; Ruiz, O.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEThis article presents a methodology for reconstruction of 3D faces which is based on stereoscopic images of the scene using active and passive surface reconstruction. A sequence of Gray patterns is generated, which are projected onto the scene and their projection recorded by a pair of stereo cameras. The images are rectified to make coincident their epipolar planes and so to generate a stereo map of the scene. An algorithm for stereo matching is applied, whose result is a bijective mapping between subsets of the pixels of the images. A particular connected subset of the images (e.g. the face) is selected by a segmentation algorithm. The stereo mapping is applied to such a subset and enables the triangulation of the two image readings therefore rendering the (x,y,z) points of the face, which in turn allow the reconstruction of the triangular mesh of the face. Since the surface might have holes, bilateral filters are applied to have the holes filled. The algorithms are tested in real conditions and we evaluate their performance with virtual datasets. Our results show a good reconstruction of the faces and an improvement of the results of passive systems.Ítem Face Reconstruction with structured light(SciTePress, 2011-03) Congote, John; Barandiaran, Iñigo; Barandiaran, Javier; Nieto, Marcos; Ruíz, Óscar; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEThis article presents a methodology for reconstruction of 3D faces which is based on stereoscopic images of the scene using active and passive surface reconstruction -- A sequence of gray patterns is generated, which are projected onto the scene and their projection recorded by a pair of stereo cameras -- The images are rectified to make coincident their epipolar planes and so to generate a stereo map of the scene -- An algorithm for stereo matching is applied, whose result is a bijective mapping between subsets of the pixels of the images -- A particular connected subset of the images (e.g. the face) is selected by a segmentation algorithm -- The stereo mapping is applied to such a subset and enables the triangulation of the two image readings therefore rendering the (x;y; z) points of the face, which in turn allow the reconstruction of the triangular mesh of the face -- Since the surface might have holes, bilateral filters are applied to have the holes filled -- The algorithms are tested in real conditions and we evaluate their performance with virtual datasets -- Our results show a good reconstruction of the faces and an improvement of the results of passive systemsÍtem Generación de ortoimágenes usando vehículos aéreos no tripulados aplicado a la agricultura(Universidad EAFIT, 2017) Lorduy Hernández, Sara; Marulanda Tobón, AlejandroÍtem Geometry and topology extraction and visualization from scalar and vector fields(Universidad EAFIT, 2013) Congote Calle, John Edgar; Ruíz Salguero, Óscar Eduardo; Posada, Jorge LeónÍtem Hessian eigenfunctions for triangular mesh parameterization(SciTePress, 2016-02-27) Mejia, D.; Ruiz OE; Cadavid, C.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEHessian Locally Linear Embedding (HLLE) is an algorithm that computes the nullspace of a Hessian functional H for Dimensionality Reduction (DR) of a sampled manifold M. This article presents a variation of classic HLLE for parameterization of 3D triangular meshes. Contrary to classic HLLE which estimates local Hessian nullspaces, the proposed approach follows intuitive ideas from Differential Geometry where the local Hessian is estimated by quadratic interpolation and a partition of unity is used to join all neighborhoods. In addition, local average triangle normals are used to estimate the tangent plane TxM at x ? M instead of PCA, resulting in local parameterizations which reflect better the geometry of the surface and perform better when the mesh presents sharp features. A high frequency dataset (Brain) is used to test our algorithm resulting in a higher rate of success (96.63%) compared to classic HLLE (76.4%). © Copyright 2016 by SCITEPRESS - Science and Technology Publications, Lda. All rights reserved.Ítem Hessian eigenfunctions for triangular mesh parameterization(SciTePress, 2016-02-27) Mejia, D.; Ruiz OE; Cadavid, C.; Mejia, D.; Ruiz OE; Cadavid, C.; Universidad EAFIT. Departamento de Ciencias; Matemáticas y AplicacionesHessian Locally Linear Embedding (HLLE) is an algorithm that computes the nullspace of a Hessian functional H for Dimensionality Reduction (DR) of a sampled manifold M. This article presents a variation of classic HLLE for parameterization of 3D triangular meshes. Contrary to classic HLLE which estimates local Hessian nullspaces, the proposed approach follows intuitive ideas from Differential Geometry where the local Hessian is estimated by quadratic interpolation and a partition of unity is used to join all neighborhoods. In addition, local average triangle normals are used to estimate the tangent plane TxM at x ? M instead of PCA, resulting in local parameterizations which reflect better the geometry of the surface and perform better when the mesh presents sharp features. A high frequency dataset (Brain) is used to test our algorithm resulting in a higher rate of success (96.63%) compared to classic HLLE (76.4%). © Copyright 2016 by SCITEPRESS - Science and Technology Publications, Lda. All rights reserved.Ítem MEDX3DOM: MEDX3D for X3DOM(ACM, 2012-08) Congote, John; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEWe present an implementation of MEDX3DOM a MEDX3D standard implemented into the X3DOM framework -- We present the report of a work in progress of the implementation identifying the critical sections to be migrated into the new architecture, and possible extensions of the standard on the Web environment -- Results for the early implementation are shown, where the visualization of medical datasets with advanced direct volume rendering algorithms are obtained under the X3DOM architecture with interactive frame rates and good image quality -- An example of the HTML5/X3DOM document is presented with futureÍtem A new evaluation framework and image dataset for keypoint extraction and feature descriptor matching(2013-02) Barandiaran, Iñigo; Cortes, Camilo; Nieto, Marcos; Graña, Manuel; Ruíz, Óscar E.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEKey point extraction and description mechanisms play a crucial role in image matching, where several image points must be accurately identified to robustly estimate a transformation or to recognize an object or a scene -- New procedures for keypoint extraction and for feature description are continuously emerging -- In order to assess them accurately, normalized data and evaluation protocols are required -- In response to these needs, we present a (1) new evaluation framework that allow assessing the performance of the state-of-the-art feature point extraction and description mechanisms, (2) a new image dataset acquired under controlled affine and photometric transformations and (3) a testing image generator -- Our evaluation framework allows generating detailed curves about the performance of different approaches, providing a valuable insight about their behavior -- Also, it can be easily integrated in many research and development environments -- The contributions mentioned above are available on-line for the use of the scientific communityÍtem Parametric Curve Reconstruction from Point Clouds using Minimization Techniques(SCITEPRESS, 2013) Ruíz, Óscar E.; Cortés, C.; Aristizábal, M.; Acosta, Diego A.; Vanegas, Carlos A.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAESmooth (C1-, C2-,...) curve reconstruction from noisy point samples is central to reverse engineering, medical imaging, etc -- Unresolved issues in this problem are (1) high computational expenses, (2) presence of artifacts and outlier curls, (3) erratic behavior at self-intersections and sharp corners -- Some of these issues are related to non-Nyquist (i.e. sparse) samples -- Our work reconstructs curves by minimizing the accumulative distance curve cs. point sample -- We address the open issues above by using (a) Principal Component Analysis (PCA) pre-processing to obtain a topologically correct approximation of the sampled curve -- (b) Numerical, instead of algebraic, calculation of roots in point-to-curve distances -- (c) Penalties for curve excursions by using point cloud to - curve and curve to point cloud -- (d) Objective functions which are economic to minimize -- The implemented algorithms successfully deal with self - intersecting and / or non-Nyquist samples -- Ongoing research includes self-tuning of the algorithms and decimation of the point cloud and the control polygonÍtem Phase-difference images by digital holography applied to 3D surface contouring(Academia Colombiana de Ciencias Exactas Físicas y Naturales, 2005-06) Velásquez-Prieto, Daniel; García Sucerquia, Jorge Iván; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaThe problem to determine the 3D-contour of objects with all sizes and shapes is a hot topic in diverse fields of optical research and engineering. Through the use of the numerical reconstruction of digital recorded holograms, we propose a technique to evaluate the 3D contour of objects at least four orders of magnitude larger than the optical wavelength. The required 2π-module phase map in any contouring process is obtained by means of phase-difference image of two digital reconstructed holograms. These holograms are interferometric recordings from a still object under different angle illumination. Our proposal is supported on the theoretical analysis of the contouring system, verified by means of numerical results.Ítem Principal component analisis-PCA-and Delone Triangulations for PL approximation C1-continuous 1-manifolds in Rn(ACTA Press, 2004-08) Ruíz, Óscar; Cadavid, Carlos; García, Manuel J.; Martinod, Ronald; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAE