Repositorio Institucional Universidad EAFIT ::Examinando por Materia "Image processing"

Examinando por Materia "Image processing"

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2D Shape similarity as a complement for Voronoi-Delone methods in shape reconstruction
(Elsevier, 2005) Ruíz S., Óscar E.; Cadavid, Carlos A.; Granados, Miguel; Peña, Sebastián; Vásquez, Eliana; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAE
In surface reconstruction from planar slices it is necessary to build surfaces between corresponding 2D regions in consecutive levels -- The problem has been traditionally attacked with (i) direct reconstruction based on local geometric proximity between the regions, and (ii) classification of topological events between the slices, which control the evolution of the cross cuts -- These approaches have been separately applied with mixed success -- In the case (i), the results may be surfaces with over-stretched or unnatural branches, resulting from a local contour proximity which does not correspond to global similarity between regions -- In (ii), the consequences from topological events upon the actual surface realization have not been drawn -- In this paper an integration of (i) and (ii) is presented, which uses a criteria of similarity between composed 2D regions in consecutive slices to: (a) decide if a surface should actually relate those regions, (b) identify the topological transitions between levels and (c) construct the local surface for the related regions -- The method implemented hinders over-stretched and unnatural branches, therefore rendering a surface which adjusts to geometrically-sound topological events -- This is a good alternative when the surface reconstructed needs to be topologically faithful (for example in flow simulation) in addition to represent the a rough geometrical space (for example in radiation planning)
Automatic Tools for Data Diagnostic and Correction in Aerophotogrametry
(INGEGRAF, 1999) Ruíz Salguero, Óscar E.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAE
En Aerofotogrametría, el proceso de restitución (paso de imagen a formato electrónico vectorizado) es realizado por un operador humano, con asistencia de hardware y Software especializado -- Dicho proceso implica la traducción de accidentes geográficos, detalles topográficos, etc., la cual conlleva errores tanto geométricos (precisión) como topológicos (conectividad) de los datos digitales vectorizados -- Adicionalmente, aun si la vectorizacion es perfecta, los editores en etapas subsecuentes deben realizar tareas repetitivas: formateo, marcado, ajuste de convenciones, etc., que por el tamaño de los archivos de datos se hacen prolongadas y propensas al error -- Tanto los procesos de corrección como de formateo y marcado requieren además la ejecución de entradas / salidas con el usuario en el computador, proceso que es particularmente lento -- Esta investigación presenta el desarrollo de herramientas automáticas de (i) detección y corrección de errores comunes en los planos restituidos, (ii) partición y re-agrupación inteligentes de planos grandes, y (iii) formateo y marcado automático -- El desarrollo de software se hace usando el standard AIS (Application Interface Specification), lo que lo hace portable a los modeladores cuya interface AIS haya sido implementada -- El proyecto se desarrolla para la firma AeroEstudios LTDA de Colombia, la cual lo ha incorporado a sus herramientas de procesamiento de información digital
Coupling Terrain and Building Database Information for Ray-Tracing Applications
(2003) Fontán, F.P.; Ruíz S., O.E.; Peña, S.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAE
In this paper a methodology for the combination and integration into a single data base of terrain and building data is presented -- This study is justified if ray-tracing techniques are to be used in propagation and channel modeling studies -- Usually terrain is available in grid or elevation form while building information is normally facet-oriented -- Ray-tracing (RT) techniques deal with flat facets and straight edges, if possible in triangular format -- To allow the use of RT on urban areas over irregular terrain a common format made up of facets and edges is therefore needed -- In this article, the procedure to accomplish this data homogeneity is presented -- It is assumed that terrain data is available in two formats: a) grid elevation and b) contour or iso-altitude lines -- Building data is assumed available in plant, polygonal planar contour form, a primitive and yet widely used format which is yet to be transformed into 3D entities -- The geometric modeling of joint terrain and building data is further difficuledt because union of surface objects (even after achieving a unified format) is undefined from the point of view of 3D boolean operations
DC term filtering techniques in digital holography
(SPIE, 2004-10-21) Velásquez-Prieto, Daniel; García Sucerquia, Jorge Iván; Herrera Ramírez, Jorge Alexis; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
In numerical hologram reconstruction like in optical holography, there exist different diffraction orders, which many times produce difficulties for the image visualizations. In numerical reconstruction, the filtering of the DC term, or zero order diffraction, provides an improved utilization of the dynamic range of the visualization systems, which is needed for the right displaying purposes of reconstructed images. In the case of the in-line set-ups, the zero diffraction order has even more devastating effects because it does not allow reconstructing the images itself as in Gabor's holograms, so it is necessary to attempt a filtering of this DC term. In this work is shown a qualitative assessment of different techniques of DC term filtering applied to numerical reconstruction of Fresnel's holograms recorded by means of off-line set-ups.
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 Andrés
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/CAE
This 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, etcetera
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/CAE
This 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
Fitting of Analytic Surfaces to Noisy Point Clouds
(Scientific Research Publishing, 2013-04) Ruíz, Óscar; Arroyave, Santiago; Acosta, Diego; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAE
Fitting -continuous or superior surfaces to a set of points sampled on a 2-manifold is central to reverse engi- neering, computer aided geometric modeling, entertaining, modeling of art heritage, etc -- This article addresses the fit- ting of analytic (ellipsoid, cones, cylinders) surfaces in general position in -- Currently, the state of the art presents limitations in 1) automatically finding an initial guess for the analytic surface F sought, and 2) economically estimat- ing the geometric distance between a point of and the analytic surface SF -- These issues are central in estimating an analytic surface which minimizes its accumulated distances to the point set -- In response to this situation, this article presents and tests novel user-independent strategies for addressing aspects 1) and 2) above, for cylinders, cones and ellipsoids -- A conjecture for the calculation of the distance point-ellipsoid is also proposed -- Our strategies produce good initial guesses for F and fast fitting error estimation for F, leading to an agile and robust optimization algorithm -- Ongoing work addresses the fitting of free-form parametric surfaces to S
Flow visualization approach for periodically reversed flows
(Begell House Inc., 2012-01-01) Botero, F.; Guzmán, S.; Hasmatuchi, V.; Roth, S.; Farhat, M.; Mecánica Aplicada
An unconventional tuft visualization method, along with an image processing technique adapted to the flow conditions, is proposed and implemented on a reduced-scale model of a Francis-type reversible pump-turbine in three different turbine stages such as turbine mode, runaway mode, and turbine break mode. The main goal of this technique is to visualize the complex flow developed during a rotating stall phenomenon. Fluorescent monofilament wires along with high-speed image processing and pressure sensors were installed in the narrow and vaneless gap between the impeller blades and guide vanes. Pressure fluctuations were analyzed along with tuft visualization to describe the flow with and without a rotating stall. The implemented tuft visualization method gives an adjusted qualitative description of the undergoing phenomena, making different flow behaviors such as backflow, high turbulences, recirculation, etc., evident. © 2012 by Begell House, Inc.
Formación y restauración de imagen en tomografía óptica de coherencia mediante posprocesamiento
(Universidad EAFIT, 2017) Cuartas Vélez, Carlos Alfredo; Restrepo Gómez, René; Uribe Patarroyo, Néstor
Generación de ortoimágenes usando vehículos aéreos no tripulados aplicado a la agricultura
(Universidad EAFIT, 2017) Lorduy Hernández, Sara; Marulanda Tobón, Alejandro
Geometry and topology extraction and visualization from scalar and vector fields
(Universidad EAFIT, 2013) Congote Calle, John Edgar; Ruíz Salguero, Óscar Eduardo; Posada, Jorge León
Marching cubes in an unsigned distance field for surface reconstruction from unorganized point sets
(2010) Congote, John; Moreno, Aitor; Barandiaran, Iñigo; Barandiaran, Javier; Posada, Jorge; Ruíz, Óscar; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAE
Surface reconstruction from unorganized point set is a common problem in computer graphics -- Generation of the signed distance field from the point set is a common methodology for the surface reconstruction -- The reconstruction of implicit surfaces is made with the algorithm of marching cubes, but the distance field of a point set can not be processed with marching cubes because the unsigned nature of the distance -- We propose an extension to the marching cubes algorithm allowing the reconstruction of 0-level iso-surfaces in an unsigned distance field -- We calculate more information inside each cell of the marching cubes lattice and then we extract the intersection points of the surface within the cell then we identify the marching cubes case for the triangulation -- Our algorithm generates good surfaces but the presence of ambiguities in the case selection generates some topological mistakes
MEDX3DOM: MEDX3D for X3DOM
(ACM, 2012-08) Congote, John; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAE
We 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 future
Meteorological Risk Early Warning System for Air Operations
(Institute of Electrical and Electronics Engineers Inc., 2019-01-01) Florez Zuluaga J.A.; David Ortega Pabon J.; Vargas Bonilla J.F.; Quintero Montova O.L.; Florez Zuluaga J.A.; David Ortega Pabon J.; Vargas Bonilla J.F.; Quintero Montova O.L.; Universidad EAFIT. Departamento de Ciencias; Modelado Matemático
Today, airspace control has the challenge of merging information from independent and heterogeneous systems in order to minimize air safety risks and facilitate the decision-making process. One of the main risks for air operations is meteorology because convective formations like Torre cumulus or cumulonimbus could generate several dangerous phenomena such as icing, wind gusts, and thunderstorms, among others, that can affect the air operation safety. Based on previous works that allow the automatic identification of convective phenomena through the fusion of multispectral satellite images and other sources as winds and Meteorological Aerodrome Report (METAR), and establishing a common georeferenced coordinates system like WGS-84, for all sources, it can generate a system that could calculate early alerts about hazardous weather conditions in the aircrafts proximality for air traffic control system. For this, a meteorological analysis system can generate information about convective clouds calculating area, heights, temperatures, risk level and position of the meteorological formation. Parallelly the convective cloud is surrounded by optimal elliptical forms centered on the convective formation, generating a meteorological object. On the other hand, there is a system responsible for monitoring the information of the surveillance sensors. This system fused the air traffic sensors available like primary and secondary radar signals and ADS-B sensors in a unique WGS-84 coordinates system. Finally, in a georeferenced raster-Type graphing system or in a Geographic Information System (GIS), the meteorological and surveillance information is correlated projecting the track routes generates by air traffic system and traces generated by meteorological objects in order to establish times and high-risk areas, early. With this information, the Air Traffic Controller (ATC) system users, could minimize risk areas and reorganize the air traffic flow. This methodology then, would contribute to the decision-making process of ATC, facilitating the air flow reorganization and minimizing meteorological risks. For the development of this project a cooperative experimental methodology by subsystems was used. It was based on an operational knowledge and normal operating procedures of the Colombian Air Force, integrated with radar tracking technologies that implement decision trees. These alerts allow the air traffic controller to assess the risk and in accordance with the evaluation, if necessary, reorganize the air traffic flow for a specific area before the aircraft enter areas of bad weather mitigating the risks. © 2019 IEEE.
Modelado 4D y monitoreo de productividad IP en proyectos de construcción
(Universidad EAFIT, 2015) Aguilar Lopera, Gabriel; Botero Botero, Luis Fernando
El presente trabajo describe los procedimientos y resultados de la profundización en implementación de realidad virtual y las TIC en procesos constructivos de un proyecto real, por medio de herramientas de modelado BIM y monitoreo con cámaras IP, que se realizó con el propósito de explorar los resultados de la aplicación de estas tecnologías en un proyecto privado de vivienda, como ayudas en los procesos de las fases de planificación y ejecución de obra; para su desarrollo se realizó un proyecto piloto en el proyecto de vivienda privada Cantagirone Tre Piu, en la ciudad de Medellín, en el cual mediante la realización de modelos 3D y 4D, y empleando el software IDEO para el monitoreo de productividad IP, se pretendió comprobar la hipótesis de que, el modelado 4D y el monitoreo IP ayuda a mejorar los proyectos de construcción en su planificación y ejecución -- Los resultados obtenidos parten de los informes de la supervisión técnica apoyada en la programación de obra, y la adquisición de datos que se obtuvieron del software IDEO durante el proceso de construcción de la estructura -- Como resultado final de la profundización se formula una propuesta de inclusión de modelado BIM 3D y 4D y monitoreo de productividad IP, como herramientas para la mejora de procesos constructivos
A new evaluation framework and image dataset for keypoint extraction and feature descriptor matching
(2013-01-01) Barandiaran, I.; Cortes, C.; Nieto, M.; Graña, M.; Ruiz, O.E.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAE
Key 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 community.
Optical vortex metrology from phase modulo 2 p maps
(2012-01-01) Sierra-Sosa, D.-E.; Angel-Toro, L.; Tebaldi, M.; Bolognini, N.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
Conventional Optical Vortex Metrology techniques rely on the generation of pseudophase maps for image processing and measuring. In our work, as a novel alternative the application of this techniquefrom phase modulo 2p maps is discussed. © OSA 2012.
Optimization and toxicity assessment of a combined electrocoagulation, H2O2/Fe2+/UV and activated carbon adsorption for textile wastewater treatment
(Elsevier, 2019-02-15) GilPavas, E; Dobrosz-Gomez, I; Gomez-Garcia, MA; GilPavas, E; Dobrosz-Gomez, I; Gomez-Garcia, MA; Universidad EAFIT. Departamento de Ingeniería de Procesos; Procesos Ambientales (GIPAB)
In this study, the potential application of sequential Electrocoagulation + Fenton (F) or Photo-Fenton (PF) + Active carbon adsorption (EC + F/PF + AC) processes were analyzed as alternatives for the treatment of an industrial textile wastewater resulting from an industrial facility located in Medellín (Colombia). In order to maximize the organic matter degradation, each step of the treatment was optimized using the Response Surface Methodology. At first, the optimal performance of EC was achieved with Fe electrodes operating at pH = 7, jEC = 10 mA/cm2 and 60 rpm, during 10 min of electrolysis. At these conditions, EC let to remove 94% of the dye's color, 56% of the COD and 54% of the TOC. Next, sequentially applied Fenton or photo-Fenton process (i.e., EC + F/PF), operating at the optimized conditions (pH = 4.3, [Fe2+] = 1.1 mM, [H2O2] = 9.7 mM, stirring velocity = 100 rpm and reaction time = 60 min.), improved the quality of the treated effluent. The EC + F let to achieve total color reduction, as well as COD and TOC removals of 72 and 75%, respectively. The EC + PF reached 100% of color, 76% of COD and 78% of TOC reductions. The EC + F/PF processes were more efficient than EC in elimination of low molecular weight (<5 kDa) compounds from wastewater. Moreover, the BOD5/COD ratio increased from 0.21 to 0.42 and from 0.21 to 0.46 using EC + F and EC + PF processes, respectively. However, EC + F/PF were not fully effective for the removal of acute toxicity to Artemia salina: 20% and 60% of reduction in toxicity using EC + F and EC + PF, respectively, comparing to very toxic (100%) raw textile wastewater. Thus, activated carbon adsorption was applied as an additional step to complete the treatment. After AC adsorption, the acute toxicity decreased to 10% and 0% using EC + F and EC + PF, respectively. The total operational costs, including chemical reagents, electrodes, energy consumption and sludge disposal, were of 1.65 USD/m3 and 2.3 USD/m3 for EC + F and EC + PF, respectively. © 2018 Elsevier B.V.
Optimization and toxicity assessment of a combined electrocoagulation, H2O2/Fe2+/UV and activated carbon adsorption for textile wastewater treatment
(Elsevier, 2019-02-15) GilPavas, E; Dobrosz-Gomez, I; Gomez-Garcia, MA; Universidad EAFIT. Departamento de Ingeniería de Procesos; Desarrollo y Diseño de Procesos
In this study, the potential application of sequential Electrocoagulation + Fenton (F) or Photo-Fenton (PF) + Active carbon adsorption (EC + F/PF + AC) processes were analyzed as alternatives for the treatment of an industrial textile wastewater resulting from an industrial facility located in Medellín (Colombia). In order to maximize the organic matter degradation, each step of the treatment was optimized using the Response Surface Methodology. At first, the optimal performance of EC was achieved with Fe electrodes operating at pH = 7, jEC = 10 mA/cm2 and 60 rpm, during 10 min of electrolysis. At these conditions, EC let to remove 94% of the dye's color, 56% of the COD and 54% of the TOC. Next, sequentially applied Fenton or photo-Fenton process (i.e., EC + F/PF), operating at the optimized conditions (pH = 4.3, [Fe2+] = 1.1 mM, [H2O2] = 9.7 mM, stirring velocity = 100 rpm and reaction time = 60 min.), improved the quality of the treated effluent. The EC + F let to achieve total color reduction, as well as COD and TOC removals of 72 and 75%, respectively. The EC + PF reached 100% of color, 76% of COD and 78% of TOC reductions. The EC + F/PF processes were more efficient than EC in elimination of low molecular weight (<5 kDa) compounds from wastewater. Moreover, the BOD5/COD ratio increased from 0.21 to 0.42 and from 0.21 to 0.46 using EC + F and EC + PF processes, respectively. However, EC + F/PF were not fully effective for the removal of acute toxicity to Artemia salina: 20% and 60% of reduction in toxicity using EC + F and EC + PF, respectively, comparing to very toxic (100%) raw textile wastewater. Thus, activated carbon adsorption was applied as an additional step to complete the treatment. After AC adsorption, the acute toxicity decreased to 10% and 0% using EC + F and EC + PF, respectively. The total operational costs, including chemical reagents, electrodes, energy consumption and sludge disposal, were of 1.65 USD/m3 and 2.3 USD/m3 for EC + F and EC + PF, respectively. © 2018 Elsevier B.V.

Examinando por Materia "Image processing"

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