Papers by Victor Simon Theoktisto Costa
hgpu.org, 2011
We derive a conformal algebra treatment unifying all types of collisions among points, vectors, a... more We derive a conformal algebra treatment unifying all types of collisions among points, vectors, areas (defined by bivectors and trivectors) and 3D solid objects (defined by trivectors and quadvectors), based in a reformulation of collision queries from Ê 3 to conformal Ê 4,1 space. The algebraic formulation in this 5D space is then implemented in GPU to allow faster parallel computation queries. Results show expected orders of magnitude improvements computing collisions among known mesh models, allowing interactive rates without using optimizations and bounding volume hierarchies.
A Functional Paradigm using the C Language for Teaching Programming for Engineers
2018 XLIV Latin American Computer Conference (CLEI), 2018
Many engineering programs place in their curricula some courses in Computer Programming, whose co... more Many engineering programs place in their curricula some courses in Computer Programming, whose content and quality are generally less rigorous than their Computer Science equivalents. Most use the C language as development tool, but the approach applies more effort in describing the language's peculiarities than exploiting the practical applications in engineering endeavors. The contributed programming techniques are born from the experience of teaching Functional Programming, embodied in headers that enhance depth and rigorousness in the development of high quality code: (i) Functional emphasis from the beginning; (ii) Formal Specifications with exception generation; (iii) Early focus in recursion, particularly tail recursion; (iv) Development of Abstract Data Types using C's opaque types; (v) Incorporation of First Order and Higher Order Functions; (vi) Efficient dynamic memory management using a "garbage collector"; (vii) Using and Integrated Developed Environment (IDE) with embedded debugger. The aforementioned headers are attached at the end of the article.
CLEI Electronic Journal, 2010
Thehapticrenderingofsurfacemesostructure(finerelieffeatures)indensetrianglemeshesrequires special... more Thehapticrenderingofsurfacemesostructure(finerelieffeatures)indensetrianglemeshesrequires special structures, equipment, and high sampling rates for detailed perception of rugged models. Low cost approaches render haptic texture at the expense of fidelity of perception. We propose a faster method for sur- face haptic rendering using image-based Hybrid Rugosity Mesostructures (HRMs), paired maps with per-face heightfield displacements and normal maps, which are layered on top of a much decimated mesh, effectively adding greater surface detail than actually present in the geometry. The haptic probe’s force response algorithm is modulated using the blended HRM coat to render dense surface features at much lower costs. The proposed method solves typical problems at edge crossings, concave foldings and texture transitions. To prove the well- ness of the approach, a usability testbed framework was built to measure and compare experimental results of haptic rendering approaches in a common...
Proceedings. 17th Brazilian Symposium on Computer Graphics and Image Processing
We characterize the feature superset of Collaborative Virtual Reality Environments (CVREs) out of... more We characterize the feature superset of Collaborative Virtual Reality Environments (CVREs) out of existing implementations, and derive a novel component framework for transforming standalone VR tools into full-fledged multithreaded collaborative environments. The contributions of our approach rely on cost-effective techniques for loading graphics rendering, user interaction and network communications software components into separate threads, with a top thread for session collaboration. The framework recasts VR tools under a scalable peer-topeer topology for scene sharing, callback hooks for event broadcasting and multicamera perspectives of avatar interaction. We validate the framework by applying it to our own ALICE VR Navigator. Experimental results show good performance of our approach in the collaborative inspection of complex models.
In w this paper we characterize a feature superset for Collaborative Virtual Reality Environments... more In w this paper we characterize a feature superset for Collaborative Virtual Reality Environments (CVRE), and derive a component framework to transform stand-alone VR navigators into full-fledged multithreaded collaborative environments. The contributions of our approach rely on a cost-effective and extensible technique for loading software components into separate POSIX threads for rendering, user interaction and network communications, and adding a top layer for managing session collaboration. The framework recasts a VR navigator under a distributed peer x-to-peer topology for scene and object sharing, using callback hooks for broadcasting remote events and multicamera perspective sharing with avatar interaction. We validate the framework by applying it to our own ALICE VR Navigator. Experimental results show that our approach has good performance in the collaborative inspection of complex models.
An image-based rugosity mesostructure for rendering fine haptic detail
Citeseer
... Fig. 2. Approaches to simulate surface details in haptic perception ... By using this haptic ... more ... Fig. 2. Approaches to simulate surface details in haptic perception ... By using this haptic perception algorithm and implementing the bump-mapping visualization as a GPU shader, we ... MG A much denser mesh based on Mb, with very small triangles following the heightfield instead ...
Enhancing collaboration in virtual reality applications
Computers & Graphics, 2005
... The first three apply to generic CVEs and the last two are ... for model construction, synchr... more ... The first three apply to generic CVEs and the last two are ... for model construction, synchronous and asynchronous collaboration modes, adaptive multiresolution strategies, interoperability standards ... DIVE, Massive-3, VELVET, GNU/Maverik seem capable of handling large user ...
Novática: Revista de la …, 2003
Resumen: la arquitectura AVANTE descrita en este artículo implementa un ambiente WBI (Web Based I... more Resumen: la arquitectura AVANTE descrita en este artículo implementa un ambiente WBI (Web Based Instruction) basado en componentes de software distribuidos CORBA (Common Object Request Broker Architecture) para manejo de cursos, identificación de ...
AVANTE: A web based instruction architecture based on XML/XSL standards, free software and distributed CORBA components
UPGRADE, 2003
AbstractThe AVANTE Architecture described in this paper, implements a WBI environment based on C... more AbstractThe AVANTE Architecture described in this paper, implements a WBI environment based on CORBA distributed software components for course management, user authentication, collaborative work, database access, presentation, and other services. ...
The present document exposes a different approach for haptic rendering, defined as the simulation... more The present document exposes a different approach for haptic rendering, defined as the simulation of force interactions to reproduce the sensation of surface relief in dense models. Current research shows open issues in timely haptic interaction involving large meshes, with several problems affecting performance and fidelity, and without a dominant technique to treat these issues properly. Relying in pure geometric collisions when rendering highly dense mesh models (hundreds of thousands of triangles) sensibly degrades haptic rates due to the sheer number of collisions that must be tracked between the mesh's faces and a haptic probe. Several bottlenecks were identified in order to enhance haptic performance: software architecture and data structures, collision detection, and accurate rendering of surface relief. To account for overall software architecture and data structures, it was derived a complete component framework for transforming standalone VR applications into full-fle...
Rendering haptic textures seamlessly out of triangle meshes just by using geometry requires heavy... more Rendering haptic textures seamlessly out of triangle meshes just by using geometry requires heavy work and does not allow high sampling rates for detailed models. Better approaches simulate surface texture without increasing much the complexity or processing cost, at the expense of fidelity of perception. We propose a prism-based method for rendering local height field maps out of an underlying triangle mesh, which relies in a space subdivision representation based in octrees for collision detection, and locally rendering ...
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Papers by Victor Simon Theoktisto Costa