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- Thomas Lewiner, Hélio Lopes, Antônio Wilson Vieira, Geovan Tavares
- J. Graphics, GPU, & Game Tools
- 2003

Marching Cubes' methods first offered visual access to experimental and theoretical data. The implementation of this method usually relies on a small lookup table. Many enhancements and optimizations of Marching Cubes still use it. However, this lookup table can lead to cracks and inconsistent topology. This paper introduces a full implementation of… (More)

- Fabiano Petronetto, Afonso Paiva, Marcos Lage, Geovan Tavares, Hélio Lopes, Thomas Lewiner
- IEEE Transactions on Visualization and Computer…
- 2010

Vector fields analysis traditionally distinguishes conservative (curl-free) from mass preserving (divergence-free) components. The Helmholtz-Hodge decomposition allows separating any vector field into the sum of three uniquely defined components: curl free, divergence free and harmonic. This decomposition is usually achieved by using mesh-based methods such… (More)

- Hélio Lopes, Jarek Rossignac, Alla Safonova, Andrzej Szymczak, Geovan Tavares
- Computers & Graphics
- 2003

- Thales Vieira, Alex Laier Bordignon, +4 authors Thomas Lewiner
- Comput. Graph. Forum
- 2009

The definition of a good view of a 3D scene is highly subjective and strongly depends on both the scene content and the 3D application. Usually, camera placement is performed directly by the user, and that task may be laborious. Existing automatic virtual cameras guide the user by optimizing a single rule, e.g. maximizing the visible silhouette or the… (More)

- Rener Castro, Thomas Lewiner, Hélio Lopes, Geovan Tavares, Alex Laier Bordignon
- Comput. Graph. Forum
- 2008

This work emerged from the following observation: usual search procedures for octrees start from the root to retrieve the data stored at the leaves. But since the leaves are the farthest nodes to the root, why start from the root? With usual octree representations, there is no other way to access a leaf. However, hashed octrees allow direct access to any… (More)

- Thomas Lewiner, Hélio Lopes, Geovan Tavares
- IEEE Transactions on Visualization and Computer…
- 2004

Morse theory is a powerful tool for investigating the topology of smooth manifolds. It has been widely used by the computational topology, computer graphics, and geometric modeling communities to devise topology-based algorithms and data structures. Forman introduced a discrete version of this theory which is purely combinatorial. We aim to build,… (More)

- Hélio Lopes, Geovan Tavares
- Symposium on Solid Modeling and Applications
- 1997

In this work, it is presented a complete set of operators , called Morse operators, to build and unbuild any combinatorial orientable &dimensional manifolds embedded in R " (n 3 3). Also, a suitable data structure, called Handl~Face, is introduced in order to represent 3manifolds with or without boundary. The main emphasis is on the boundary of the manifold… (More)

- Thomas Lewiner, Hélio Lopes, Geovan Tavares
- Comput. Geom.
- 2003

Morse theory is a powerful tool in its applications to computational topology, computer graphics and geometric modeling. It was originally formulated for smooth manifolds. Recently, Robin Forman formulated a version of this theory for discrete structures such as cell complexes. It opens up several categories of interesting objects (particularly meshes) to… (More)

- Afonso Paiva, Fabiano Petronetto, Thomas Lewiner, Geovan Tavares
- 2006 19th Brazilian Symposium on Computer…
- 2006

This paper presents a new visually realistic animation technique for objects that melt and flow. It simulates viscoplastic properties of materials such as metal, plastic, wax, polymer and lava. The technique consists in modeling the object by the transition of a non-Newtonian fluid with high viscosity to a liquid of low viscosity. During the melting, the… (More)

- Hélio Lopes, Geovan Tavares, Jarek Rossignac, Andrzej Szymczak, Alla Safonova
- Symposium on Solid Modeling and Applications
- 2002

The Edgebreaker is an efficient scheme for compressing triangulated surfaces. A surprisingly simple implementation of Edgebreaker has been proposed for surfaces homeomorphic to a sphere. It uses the Corner-Table data structure, which represents the connectivity of a triangulated surface by two tables of integers, and encodes them with less than 2 bits per… (More)