Documentos de conferencia

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https://hdl.handle.net/10784/28291

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Examinando Documentos de conferencia por Materia "Algorithms"

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    Ítem
    Parametric curve reconstruction from point clouds using minimization techniques
    (2013-01-01) Ruiz, O.E.; Cortés, C.; Aristizábal, M.; Acosta, D.A.; Vanegas, C.A.; Universidad EAFIT. Departamento de Ingeniería de Procesos; Desarrollo y Diseño de Procesos
    Curve reconstruction from noisy point samples is central to surface reconstruction and therefore to reverse engineering, medical imaging, etc. Although Piecewise Linear (PL) curve reconstruction plays an important role, smooth (C1-, C2-,?) curves are needed for many applications. In reconstruction of parametric curves from noisy point samples there remain unsolved issues such as (1) high computational expenses, (2) presence of artifacts and outlier curls, (3) erratic behavior of self-intersecting curves, and (4) erratic excursions at sharp corners. Some of these issues are related to non-Nyquist (i.e. sparse) samples. In response to these shortcomings, this article reports the minimization-based fitting of parametric curves for noisy point clouds. Our approach features: (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 polygon.
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    Ítem
    Statistical tuning of adaptive-weight depth map algorithm
    (SPRINGER, 2011-01-01) Hoyos, Alejandro; Congote, John; Barandiaran, Inigo; Acosta, Diego; Ruiz, Oscar; Universidad EAFIT. Departamento de Ingeniería de Procesos; Desarrollo y Diseño de Procesos
    In depth map generation, the settings of the algorithm parameters to yield an accurate disparity estimation are usually chosen empirically or based on unplanned experiments. A systematic statistical approach including classical and exploratory data analyses on over 14000 images to measure the relative influence of the parameters allows their tuning based on the number of bad-pixels. Our approach is systematic in the sense that the heuristics used for parameter tuning are supported by formal statistical methods. The implemented methodology improves the performance of dense depth map algorithms. As a result of the statistical based tuning, the algorithm improves from 16.78% to 14.48% bad-pixels rising 7 spots as per the Middlebury Stereo Evaluation Ranking Table. The performance is measured based on the distance of the algorithm results vs. the Ground Truth by Middlebury. Future work aims to achieve the tuning by using significantly smaller data sets on fractional factorial and surface-response designs of experiments. © 2011 Springer-Verlag.
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    Publicación
    Vision 3-D with images 2-D, by mediate the analysis of shades for the illumination angle with the surface
    (SPIE-INT SOC OPTICAL ENGINEERING, 2001-08-14) Diaz, AG; Universidad EAFIT. Departamento de Ingeniería de Producción; Ingeniería, Energía, Exergía y Sostenibilidad (IEXS)
    This paper deals with the presentation of an algorithm for acquisition and processing of images, in order to obtain information of topologic aspects in a 3D surface, starting from 2D images, by means of the analysis of the shine of the risings of the surface, when this is illuminated by light sources in oblique direction. In the surface, some areas of shine appear corresponding to the areas of the rising surfaces with slopes in front of the illumination source, and shade areas corresponding to the sinking of the surfaces. When obtaining several images of the same area, by illuminating the opposite sides and by realizing operations with them, it is obtained information on the geometry and situation of the relief elements, like elevations and depths of the surface. On this basis a novel algorithm has been developed for the detection of the situations and characteristics of the threads in structures of plane textures, in the process of detection of textile shortcomings.