Examinando por Autor "Aristizábal, Mauricio"
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Ítem Hardware-accelerated Web Visualization of Vector Fields. Case Study in Oceanic Currents(2012) Aristizábal, Mauricio; Congote, John Edgar; Segura, Álvaro; Moreno, Aitor; Arregui, Harbil; Ruíz, O.Visualization of vector fields plays an important role in research activities nowadays -- Increasing web applications allow a fast, multi-platform and multi-device access to data -- As a result, web applications must be optimized in order to be performed heterogeneously as well as on high-performance as on low capacity devices -- This paper presents a hardware-accelerated scheme for integration-based flow visualization techniques, based on a hierarchical integration procedure which reduces the computational effort of the algorithm from linear to logarithmic, compared to serial integration methodologies -- The contribution relies on the fact that the optimization is only implemented using the graphics application programming interface (API), instead of requiring additional APIs or plug-ins -- This is achieved by using images as data storing elements instead of graphical information matrices -- A case study in oceanic currents is implementedÍtem ReWeb3D: enabling desktop 3D applications to run in the web(ACM, 2013) Glander, Tassilo; Moreno, Aitor; Aristizábal, Mauricio; Congote, John; Posada, Jorge; García-Alonso, Alejandro; Ruíz, Oscar; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAECurrently, 3D rendering is accessible within Web browsers through open standards such as WebGL, X3D, and X3DOM -- At the same time, there is wealth of mature desktop software which comprises algorithms, data structures, user interfaces, databases, etc -- It is a challenge to reuse such desktop software using the Web visualization resources -- In response to this challenge, this article presents a novel framework, called ReWeb3D, which minimizes the redevelopment for migration of existing 3D applications to the Web -- The redeployed application runs on a Web server -- ReWeb3D captures lowlevel graphic calls including geometry, texture, and shader programs -- The captured content is then served as a WebGLenabled web page that conveys full interactivity to the client -- By splitting the graphics pipeline between client and server, the workload can be balanced, and highlevel implementation details and 3D content are hidden -- The feasibility of ReWeb3D has been tested with applications which use OpenSceneGraph as rendering platform -- The approach shows good results for applications with large data sets (e.g. geodata), but is less suited for applications intensive in animations (e.g. games)Ítem Sensitivity analysis in optimized parametric curve fitting(Emerald Group Publishing, 2015) Ruíz, Óscar E.; Cortés, Camilo; Acosta, Diego A.; Aristizábal, Mauricio; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEPurpose – Curve fitting from unordered noisy point samples is needed for surface reconstruction in many applications -- In the literature, several approaches have been proposed to solve this problem -- However, previous works lack formal characterization of the curve fitting problem and assessment on the effect of several parameters (i.e. scalars that remain constant in the optimization problem), such as control points number (m), curve degree (b), knot vector composition (U), norm degree (k), and point sample size (r) on the optimized curve reconstruction measured by a penalty function (f) -- The paper aims to discuss these issues -- Design/methodology/approach - A numerical sensitivity analysis of the effect of m, b, k and r on f and a characterization of the fitting procedure from the mathematical viewpoint are performed -- Also, the spectral (frequency) analysis of the derivative of the angle of the fitted curve with respect to u as a means to detect spurious curls and peaks is explored -- Findings - It is more effective to find optimum values for m than k or b in order to obtain good results because the topological faithfulness of the resulting curve strongly depends on m -- Furthermore, when an exaggerate number of control points is used the resulting curve presents spurious curls and peaks -- The authors were able to detect the presence of such spurious features with spectral analysis -- Also, the authors found that the method for curve fitting is robust to significant decimation of the point sample -- Research limitations/implications - The authors have addressed important voids of previous works in this field -- The authors determined, among the curve fitting parameters m, b and k, which of them influenced the most the results and how -- Also, the authors performed a characterization of the curve fitting problem from the optimization perspective -- And finally, the authors devised a method to detect spurious features in the fitting curve -- Practical implications – This paper provides a methodology to select the important tuning parameters in a formal manner -- Originality/value - Up to the best of the knowledge, no previous work has been conducted in the formal mathematical evaluation of the sensitivity of the goodness of the curve fit with respect to different possible tuning parameters (curve degree, number of control points, norm degree, etc.)Ítem Sensitivity analysis of optimized curve fitting to uniform-noise point samples(2012-05) Ruíz, Óscar; Cortes, Camilo; Acosta, Diego; Aristizábal, Mauricio; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAECurve reconstruction from noisy point samples is needed for surface reconstruction in many applications (e.g. medical imaging, reverse engineering,etc.) -- Because of the sampling noise, curve reconstruction is conducted by minimizing the fitting error (f), for several degrees of continuity (usually C0, C1 and C2) -- Previous works involving smooth curves lack the formal assessment of the effect on optimized curve reconstruction of several inputs such as number of control points (m), degree of the parametric curve (p), composition of the knot vector (U), and degree of the norm (k) to calculate the penalty function (f) -- In response to these voids, this article presents a sensitivity analysis of the effect of mand k on f -- We found that the geometric goodness of the fitting (f) is much more sensitive to m than to k -- Likewise, the topological faithfulness on the curve fit is strongly dependent on m -- When an exaggerate number of control points is used, the resulting curve presents spurious loops, curls and peaks, not present in the input data -- We introduce in this article the spectral (frequency) analysis of the derivative of the curve fit as a means to reject fitted curves with spurious curls and peaks -- Large spikes in the derivative signal resemble Kronecker or Dirac Delta functions, which flatten the frequency content adinfinitum -- Ongoing work includes the assessment of the effect of curve degree p on f for non-Nyquist point samplesÍtem Visualization of flow fields in the web platform(2012) Aristizábal, Mauricio; Congote, John; Segura, Álvaro; Moreno, Aitor; Arregui, Harbil; Ruíz, Óscar; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEVisualization of vector fields plays an important role in research activities nowadays -- Web applications allow a fast, multi-platform and multi-device access to data, which results in the need of optimized applications to be implemented in both high-performance and low-performance devices -- Point trajectory calculation procedures usually perform repeated calculations due to the fact that several points might lie over the same trajectory -- This paper presents a new methodology to calculate point trajectories over highly-dense and uniformly-distributed grid of points in which the trajectories are forced to lie over the points in the grid -- Its advantages rely on a highly parallel computing architecture implementation and in the reduction of the computational effort to calculate the stream paths since unnecessary calculations are avoided, reusing data through iterations -- As case study, the visualization of oceanic currents through in the web platform is presented and analyzed, using WebGL as the parallel computing architecture and the rendering Application Programming Interface