Oscar Figueiredo

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We propose a new approach for developing parallel I/O-and compute-intensive applications on distributed memory PC. Using the CAP Computer-Aided Parallelization tool, application programmers create separately the serial program parts and express the parallel behavior of the program at a high level of abstraction. This high-level parallel program description(More)
Curved cross-sections extracted from medical volume images are useful for analyzing nonplanar anatomic structures such as the aorta arch or the pelvis. For visualization and for performing distance measurements, extracted surface sections need to be adequately flattened. We present two different distance preserving surface flattening methods which preserve(More)
Existing algorithms for rendering Bézier curves and surfaces fall into two categories: iterative evaluation of the parametric equations (generally using forward differencing techniques) or recursive subdivision. In the latter case, all the algorithms rely on an arbitrary precision constant (tolerance) whose appropriate choice is not clear and not linked to(More)
We propose in this paper a new approach to three-dimensional digital lines (3DDLs) based on the study of the integer lattice generated by the projection of Z 3 onto an euclidean plane which reduces the problem to dimension 2. The many properties of this lattice lead to an arithmetical deenition of 3DDLs in accordance with a topological characterization.(More)
Visualization of 3D tomographic images by slicing, i.e. by intersecting a 3D tomographic image with a plane having any desired position and orientation is a tool of choice both for learning and for diagnosis purposes. In this project, a parallel Visible Human Slice Web server has been developed, which offers to any Web client the capability of interactively(More)
The current deenition of 3D digital lines 3 , which uses the 2D digital lines of closest integer points (Bresenham's lines) of two projections, has several drawbacks: the discrete topology of this 3D digital line notion is not clear, its third projection is, generally, not the closest set of points of the third euclidean projection, if we consider a family(More)