Resumo em Inglês:

In some applications, as in image registration of serial sections in biology or medicine, it is often necessary to find a rigid body transformation that matches features under natural deformations in two images. Usual approaches deal with natural deformation as a problem of error minimization of displacement of markers. In this paper we present a registration technique which effectively models the deformation by using the physical model of an elastically deformable thin plate. The proposed method makes use of Thin Plate Splines as a registration function enabling a clear separation between the effects of the sensor positioning and the effects of deformations. The application of the method is shown using simulated data, and its strengths and flaws are analyzed

Resumo em Inglês:

The automated star/galaxy discrimination problem is a broadly studied issue of astronomical imaging. The success of a discrimination task depends on the features selected to characterize both classes of interest. In this work we propose an original approach to the characterization of these astronomical objects through the use of Mathematical Morphology, based on gray-level shape-size information. Our method consists of image preprocessing, segmentation and feature extraction steps, all of which employ Mathematical Morphology tools that were implemented using the MMach toolbox for the Khoros system. We briefly present a comparison between our segmentation results, based on the watershed method, and those of the SExtractor software package. The shape-size features are extracted through the use of the gray-level morphological pattern spectrum, which yields attractive analysis attributes that promise to be very suitable for future work in neural-network-based automatic classification

Resumo em Inglês:

We discuss the problem of adaptive polygonization of regular surfaces of the euclidean 3D space, and present effective algorithms for computing optimal polygonizations of surfaces described in parametric or implicit form

Resumo em Inglês:

This paper describes a generic algorithm for iso-line, iso-strip, iso-surface, and iso-volume visualization of unstructured 3D meshes, such as finite element models. The four types of visualization are integrated in the same data representation. Consequently iso-volume contouring is trivially implemented as a combination of iso-strip and iso-surface patches of surfaces. The algorithm can handle cells of any shape, even those that result from sectioning off parts of the model with cutting planes. The contoured stress results of two finite element analysis are shown as examples

Resumo em Inglês:

Many approaches have been proposed to generate the shape interpolation or morphing of two polyhedral objects given in a facet based representation. Most of them focus only the correspondence problem, leaving the interpolation process to just an interpolation of corresponding vertices. In this article we present a new approach which uses fields of directions defined on triangulations(FDTs) to treat both the problem of getting an homeomorphism between the models and that of morphing them. Consider that an scaled version(P1 ) of one of the objects, has already been adequately placed in the interior of the other(P2. ) The objective of the first part of the approach, is to obtain a field of unit vectors defined on a triangulation of the space between P1 and P2. This field must have no singularities and the trajectories determined by it will be later used to get warping and morphing transformations between P1 and P2. The morphing transformations obtained have the good property of being topology preserving ones but it can be hard to get an FDT defined on a triangulation of P1 - P2 and the intermediate models can have a very large number of faces. To illustrate those aspects, transformations between simple models are presented