Examinando por Materia "Image processing - Digital techniques"
Mostrando 1 - 14 de 14
Resultados por página
Opciones de ordenación
Ítem Analysis of vibrations in a plate using interferometric methods(SPIE, 2004-10-21) Ángel-Toro, Luciano; Prieto, Daniel Velasquez; Rueda Muñóz, Edgar Alberto; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaIn this work some frequencies and modes of vibration of a thin plate were determined using interferometric methods like: real-time holographic interferometry, time-average holographic interferometry, digital speckle pattern interferometry DSPI. And the results obtained are compared with those obtained with the program of finite elements COSMOS.Ítem Diagnostic study on shape perception errors within 3D-modeling courses(Universidad EAFIT, 2015) Ochoa Gutiérrez, Sebastián; Ramos Betancur, Juan DiegoForm has always been a central concern for design -- Several tools and strategies have been developed aiming to support form generation from different perspectives -- And these issues are also a matter of study for design education -- Under this view, it is relevant to explore how technology and new interactions can aid design students to better understand form generation -- The present study, therefore, is centered on the 3D-modeling courses (ID0245-Modelación 3D1 and ID0267- Modelación 3D2) and tools (PTC® Creo 3.0™) provided inside the Product Design Engineering syllabus at EAFIT University -- In the ever changing academic world, new generations of students will be always in need of new methodological approaches from educators, in order to better understand the knowledge they are being given -- Curriculum adaptations will be always necessary to achieve this goal -- Therefore, the scope of the present study aims to set the ground for new teaching strategies around the 3D-modeling courses, based on the most commonly identified errors and difficulties found in 3D-modeling students -- These errors or difficulties might not be isolated factors, only present in the named courses -- They can be intrinsically connected with the acquired skills from other form generation-related courses, such as Drawing and Projects (where physical model are built and techniques are introduced by guidance) -- However, since the project is framed by the mentioned 3D-modeling tools and courses, it is necessary to understand how form is being generated inside 3D digital environments as a starting point for future work -- Nowadays, individual software provide increasing capabilities to help achieving specific modeling tasks -- This segmentation and specialization demands high expertize from users to become accustomed and keep up with the ever demanding industry standards -- Nonetheless, speed and quality cannot be compromised -- Hence, the main target around the study will be design students that take their first steps towards product embodiment -- The project, therefore, aims to understand how students approach styling activities and to report on their most common mistakes -- It is based on how they perceive 2D representations of products and how accurate their 3D-models are, based on selected shape properties -- This will serve as an essential input for new teaching strategies towards students’ self-awareness when performing in 3D form-giving environmentsÍtem Digital material laboratory: Wave propagation effects in open-cell aluminium foams(Elsevier, 2012-09) Saenger, E.H.; Uribe, D.; Jänicke, R.; Ruíz, O.; Steeb, H.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEThis paper is concerned with numerical wave propagation effects in highly porous media using digitized images of aluminum foam -- Starting point is a virtual material laboratory approach -- The Aluminum foam microstructure is imaged by 3D X-ray tomography -- Effective velocities for the fluid-saturated media are derived by dynamic wave propagation simulations -- We apply a displacement-stress rotated staggered fnite-difference grid technique to solve the elastodynamic wave equation -- The used setup is similar to laboratory ultrasound measurements and the computed results are in agreement with our experimental data -- Theoretical investigations allow to quantify the influence of the interaction of foam and fluid during wave propagation – Together with simulations using an artificial dense foam we are able to determine the tortuosity of aluminum foamÍtem 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 estructuras 3D a partir de imágenes 2D(Universidad EAFIT, 2008) Ortiz Quintero, Juan Fernando; Soto Duque, Oscar Eduardo; Trefftz Gómez, HelmuthÍtem Implementación de un sistema de control para un sistema activo de estabilización de franjas con acceso remoto vía RENATA(Universidad EAFIT, 2013) Espitia Gómez, Javier Enrique; Ángel Toro, Luciano AlbertoÍtem Improvement of the signal-to-noise ratio in digital holography(Sociedad Mexicana de Física, 2005-02) Velásquez-Prieto, Daniel; Herrera Ramírez, Jorge Alexis; García Sucerquia, Jorge Iván; Velásquez-Prieto, Daniel; Herrera Ramírez, Jorge Alexis; García Sucerquia, Jorge Iván; Universidad EAFIT. Departamento de Ciencias Básicas; dvelas@eafit.edu.co; Óptica AplicadaA fundamental problem in optical and digital holography is the presence of speckle noise in the reconstruction process, which essentially diminishes the signal to noise ratio (SNR). For many applications, that reduction of the SNR makes the digital holography impractical, so great number of approaches have been carried out in order to overcome such a problem. They range from modifying the spatial coherence of the illumination to the application of image processing techniques. In this paper we propose the merged use of digital image processing techniques in order to increase this SNR by reducing the speckle noise in the digital reconstruction of optically recorded Fresnel’s holograms. The proposed techniques are illustrated with experimental results.Ítem Medición de distancias por medio de visión robótica(Universidad EAFIT, 2008) Peláez Uribe, Juan Sebastián; Díaz Torres, Adalberto GabrielÍtem Numerical estimation of Carbonate properties using a digital rock physics workflow(2014) Osorno, M.; Uribe, D.; Saenger, E.H.; Madonna, C.; Steeb, H.; Ruíz, Ó.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEDigital rock physics combines modern imaging with advanced numerical simulations to analyze the physical properties of rocks -- In this paper we suggest a special segmentation procedure which is applied to a carbonate rock from Switzerland -- Starting point is a CTscan of a specimen of Hauptmuschelkalk -- The first step applied to the raw image data is a nonlocal mean filter -- We then apply different thresholds to identify pores and solid phases -- Because we are aware of a nonneglectable amount of unresolved microporosity we also define intermediate phases -- Based on this segmentation determine porositydependent values for the pwave velocity and for the permeability -- The porosity measured in the laboratory is then used to compare our numerical data with experimental data -- We observe a good agreement -- Future work includes an analytic validation to the numerical results of the pwave velocity upper bound, employing different filters for the image segmentation and using data with higher resolutionÍtem Reduction of speckle noise in digital holography(SPIE, 2004-10-21) Velásquez-Prieto, Daniel; García Sucerquia, Jorge Iván; Castañeda Sepúlveda, Román; Herrera Ramírez, Jorge Alexis; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaA fundamental problem in holography, as well optical as digital, is the presence of speckle noise in the reconstruction process -- Many approaches have been carried out in order overcome such a problem, ranging from altering the spatial coherence (optical techniques) of the illumination to imaging processing techniques (digital techniques) -- This work shows the merged use of digital i maging techniques in order t o reduce the speckle noise in digital reconstruction of optically recorded Fresnel's holograms -- The proposed filtering techniques are illustrated with experimental results --Ítem Seismic Data compression using 2D Lifting-Wavelet algorithms(Universidad EAFIT, 2014-12-19) Fajardo Ariza, Carlos Augusto; Reyes Torres, Oscar Mauricio; Ramirez Silva, Ana Beatriz; Ecopetrol; Universidad Industrial de Santander; Purdue UniversityÍtem Speckle photography through different multiaperture pupils(SPIE/ 18th Congress of the International Commission for Optics, 1999-07-19) Ángel Toro, Luciano; Tebaldi, Myrian Cristina; Bolognini, Néstor Alberto; Trivi, Marcelo Ricardo; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaAn image multiplexing method based on the internal modulation of speckle grains by employing different multiple aperture pupils for recording is proposed. The interferometric fringes profile and visibility in the Fourier plane, for uniform in-plane displacement double- exposed specklegrams through different pupils recording, are analyzed in terms of the geometric parameters of the pupils. Experimental evidences are presented.Ítem Three-dimensional surface contouring of macroscopic objects by means of phase-difference images(OSA, 2006-04-16) García Sucerquia, Jorge Iván; Velásquez Prieto, Daniel Ignacio; García Sucerquia, Jorge Iván; Velásquez Prieto, Daniel Ignacio; Universidad EAFIT. Departamento de Ciencias Básicas; dvelas@eafit.edu.co; Óptica AplicadaWe report a technique to determine the 3D contour of objects with dimensions of at least 4 orders of magnitude larger than the illumination optical wavelength. Our proposal is based on the numerical reconstruction of the optical wave field of digitally recorded holograms. The required modulo 2 phase map in any contouring process is obtained by means of the direct subtraction of two phase-contrast images under different illumination angles to create a phase-difference image of a still object. Obtaining the phase-difference images is only possible by using the capability of numerical reconstruction of the complex optical field provided by digital holography. This unique characteristic leads us to a robust, reliable, and fast procedure that requires only two images. A theoretical analysis of the contouring system is shown, with verification by means of numerical and experimental results. © 2006 Optical Society of AmericaÍtem Uso del Análisis Digital de Imágenes (ADI) como herramienta para el estudio petrográfico en rocas metamórficas(Universidad EAFIT, 2016) Londoño Vargas, Yodis Daniela; Marín Cerón, María IsabelLos retos en las actividades de innovación en docencia, se basan en la necesidad de proponer nuevos métodos y estrategias que permitan ampliar y armonizar toda clase de recursos que se tengan disponibles, para potencializar los resultados en el proceso de enseñanza - aprendizaje -- En el caso de la asignatura de rocas metamórficas, es muy común identificar dificultades en los estudiantes en el análisis petrográfico, identificación de minerales, patrones texturales, y relación con curvas de blastesis; por lo anterior se quiso implementar el tratamiento de análisis digital de imágenes (ADI), como una herramienta pedagógica que facilite el aprendizaje de los mismos