Examinando por Autor "Ruiz, Oscar"
Mostrando 1 - 7 de 7
Resultados por página
Opciones de ordenación
Ítem Geometrical degeneracy removal by virtual disturbances - An application to surface reconstruction from point slice samples(INSTICC-INST SYST TECHNOLOGIES INFORMATION CONTROL & COMMUNICATION, 2008-01-01) Ruiz, Oscar; Vasquez, Eliana; Pena, Sebastian; Granados, Miguel; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEIn surface reconstruction from slice samples (typical in medical imaging, coordinate measurement machines, stereolithography, etc.) the available methods attack the geometrical and topological properties of the surface. Topological methods classify the transitions occurred in the 2-manifold between two consecutive slices i and i+ 1. Geometrical methods synthesize the surface based on local proximity of the contours in consecutive slices. Superimposed 2D Voronoi Diagrams VDi and VDi+1 for slices i and i + 1, respectively, present topological problems if, for example, a site of VD i lies on an site or an edge of VDi+1. The usual treatment of this problem in literature is to apply a geometrical disturbance to either VDi or VDi+1, thus eliminating the degeneracy. In contrast, this article presents the implementation of a method which identifies the degenerate situation, constructs un-instantiated topological constructs, choses a geometrical instantiation based on a virtual disturbance introduced to the actual configuration. The algorithm was successfully applied to remove non-manifold topologies produced by well known algorithms in surface reconstruction.Ítem Low level direct interpolation for parametric curves(Universidad EAFIT, 1998) Ruiz, Oscar; Martínez, Adriana; Rendón, Elizabeth; Universidad EAFITÍtem Spring-particle model for hyperelastic cloth(UNIV NAC COLOMBIA, FAC NAC MINAS, 2007-03-01) Garcia, Manuel; Gomez, Mario; Ruiz, Oscar; Boulanger, Pierre; Mecánica AplicadaThis article presents a computational model to simulate the deformation of hyperelastic fabrics. The model is based on a spring-particle approach and it simulates the interaction of a textile tissue with a forming body. The fabric is represented by rectangular meshes of springs. This fact enables the model to behave orthotropically and therefore it is possible to simulate the warp and weft properties. The constitutive relations preserve the natural hyperelastic capabilities of the cloth. In the model developed herein, initially the cloth lies in its relaxed un-deformed state. Then it is given an initial deformation that guarantees no contact nor intersection with the forming rigid body. Finally, the deformed cloth is realised, and moves iteratively towards an equilibrium location. The final equilibrium location is reached when the internal forces are balanced by the external contact forces caused by the rigid object. This is achieved when the stop criterion has been satisfied.Ítem Statistical assessment of global and local cylinder wear(IEEE, 2007-01-01) Ruiz, Oscar; Vanegas, Carlos; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEAssessment of cylindricity has been traditionally performed on the basis of cylindrical crowns containing a set of points that are supposed to belong to a controlled cylinder. As such, all sampled points must lie within a crown. In contrast, the present paper analyzes the cylindricity for wear applications, in which a statistical trend is assessed, rather than to assure that all points fall within a given tolerance. Principal Component Analysis is used to identify the central axis of the sampled cylinder, allowing to And the actual (expected value of the) radius and axis of the cylinder. Application of k-cluster and transitive closure algorithms allow to identify particular areas of the cylinder which are specially deformed. For both, the local areas and the global cylinder, a quantile analysis allows to numerically grade the degree of deformation of the cylinder. The algorithms implemented are part of the CYLWEAR© system and used to assess local and global wear cylinders. © 2007 IEEE.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 ProcesosIn 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.Ítem Tuning of adaptive weight depth map generation algorithms: Exploratory data analysis and design of computer experiments (DOCE)(SPRINGER, 2013-09-01) Acosta, Diego; Barandiaran, Inigo; Congote, John; Ruiz, Oscar; Hoyos, Alejandro; Grana, Manuel; Universidad EAFIT. Departamento de Ingeniería de Procesos; Desarrollo y Diseño de ProcesosIn depth map generation algorithms, parameters settings to yield an accurate disparity map estimation are usually chosen empirically or based on unplanned experiments. Algorithms' performance is measured based on the distance of the algorithm results vs. the Ground Truth by Middlebury's standards. This work shows a systematic statistical approach including exploratory data analyses on over 14000 images and designs of experiments using 31 depth maps to measure the relative influence of the parameters and to fine-tune them based on the number of bad pixels. The implemented methodology improves the performance of adaptive weight based dense depth map algorithms. As a result, the algorithm improves from 16.78 to 14.48 % bad pixels using a classical exploratory data analysis of over 14000 existing images, while using designs of computer experiments with 31 runs yielded an even better performance by lowering bad pixels from 16.78 to 13 %. © 2012 Springer Science+Business Media, LLC.Ítem Tuning of adaptive weight depth map generation algorithms: Exploratory data analysis and design of computer experiments (DOCE)(SPRINGER, 2013-09-01) Acosta, Diego; Barandiaran, Inigo; Congote, John; Ruiz, Oscar; Hoyos, Alejandro; Grana, Manuel; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEIn depth map generation algorithms, parameters settings to yield an accurate disparity map estimation are usually chosen empirically or based on unplanned experiments. Algorithms' performance is measured based on the distance of the algorithm results vs. the Ground Truth by Middlebury's standards. This work shows a systematic statistical approach including exploratory data analyses on over 14000 images and designs of experiments using 31 depth maps to measure the relative influence of the parameters and to fine-tune them based on the number of bad pixels. The implemented methodology improves the performance of adaptive weight based dense depth map algorithms. As a result, the algorithm improves from 16.78 to 14.48 % bad pixels using a classical exploratory data analysis of over 14000 existing images, while using designs of computer experiments with 31 runs yielded an even better performance by lowering bad pixels from 16.78 to 13 %. © 2012 Springer Science+Business Media, LLC.