Paulo Roma Cavalcanti

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This paper deals with the problem of creating and maintaining a spatial subdivision, deened by a set of surface patches. The main goal is to create a set of functions which provides a layer of abstraction capable of hiding the geometric and topological problems which occur when one creates and manipulates spatial subdivisions. The study of arbitrary spatial(More)
In this paper we summarize our experiences with 3D constrained Delaunay triangulation algorithms for industrial applications. In addition, we report a robust implementation process for constructing 3D constrained triangulations from initial unconstrained triangulations, based on a minimalist approach, in which we minimize the use of geometrical operations(More)
A strategy is presented to define background meshes based on crystal lattices. Crystal-based background meshes have much better initial distribution of minimum dihedral angles than regular background meshes, facilitating the optimization procedures that rely on previously defined tetrahedral meshes. In addition, these background meshes can reduce(More)
We describe a free-form stroke-based modeling system where objects are primarily represented by means of variational surfaces. Although similar systems have been described in recent years, our approach achieves both a good performance and reduced surface leak problems by employing a coarse mesh as support for constraint points. The prototype implements an(More)
This paper presents a description of the reorganization of a geometric modeler, MG, designed to support new capabilities of a topological module (CGC) that allows the detection of closed-off solid regions described by surface patches in non-manifold geometric models defined by NURBS. These patches are interactively created by the user by means of the(More)
We address the problem of an efficient image-space reconstruction of adaptively sampled scenes in the context of point-based and line-based graphics. The image-space reconstruction offers an advantageous time complexity compared to surface splatting techniques and, in fact, our improved GPU implementation performs significantly better than splatting(More)
This article presents a simple hierarchical adaptation of the Marching Cubes algorithm for polygonizing variational implicit surfaces used in modelling and reconstruction applications. The technique relies on placing the normal and boundary constraint points respecting a pseudo-Euclidean distance metrics. This procedure makes it possible to quickly prune(More)
This article discusses an enhanced polygonization algorithm for variational implicit surfaces. The polygonization scheme is a simple hierarchical adaptation of the Marching Cubes algorithm which takes advantage of some properties of variational implicits to produce a proper and efficient sampling of the surface. The technique exploits the fact that(More)