This paper addresses the metamorphosis of soft objects built from skeletons. We propose a new approach that may be split into three steps. The first step consists in an original splitting of the initial and the final ...
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This paper addresses the metamorphosis of soft objects built from skeletons. We propose a new approach that may be split into three steps. The first step consists in an original splitting of the initial and the final shapes with a view to creating a bijective graph of correspondence. In the second step, we assume that the skeletons are convex polygonal shapes, and thus take advantage of the properties of Minkowski sums to characterize the skeletons of intermediate shapes. Eventually, we characterize the intermediate distance and field functions;we describe a set of interpolation methods and propose to use a restricted class of parametrized distance and field functions so as to preserve coherence and speed-up computations. We show that we can easily extend those results to achieve a Bezier like metamorphosis where control points are replaced by control soft objects;in this scope, we have adapted existing accelerated techniques that build a Bezier transformation from a set of convex polyhedra to any bind of convex polygonal shapes. Eventually, we point out that matching all components of the initial and the final shapes generates amorphous intermediate shapes based on an overwhelming number of intermediate sub-components. Thus, we propose heuristics with a view to preserving coherence during the transformation and accelerating computations. We have implemented and tested our techniques in an experimental ray-tracer.
For rendering curved surfaces, one of the most popular techniques is metaballs, an implicit model based on isosurfaces of potential fields. This technique is suitable for deformable objects and CSG model. For renderin...
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For rendering curved surfaces, one of the most popular techniques is metaballs, an implicit model based on isosurfaces of potential fields. This technique is suitable for deformable objects and CSG model. For rendering metaballs, intersection tests between rays and isosurfaces are required. By defining the higher degree of functions for the field functions, richer capability can be expected, i.e., the smoother surfaces. However, one of the problems is that the intersection between the ray and isosurfaces can not be solved analytically for such a high degree function. Even though the field function is expressed by degree six polynomial in this paper (that means the degree six equation should be solved for the intersection test), in our algorithm, expressing the field function on the ray by Bezier functions and employing Bezier Clipping, the root of this function can be solved very effectively and precisely. This paper also discusses a deformed distribution function such as ellipsoids and a method displaying transparent objects such as clouds.
Computer displays of colorful and undulating lava-like forms will decorate living rooms of the future. These forms can already be created using mathematical simulations and hardware-assisted, isosurface computer graph...
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In the "figure detection task" the strength of segregation for a particular texture pair was estimated by the threshold amount of added disorder that prevented segregation of a textured figure from a texture...
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In the "figure detection task" the strength of segregation for a particular texture pair was estimated by the threshold amount of added disorder that prevented segregation of a textured figure from a textured ground. Disorder was either jitter in the orientation of the texture elements, or jitter in their xy positions, or a mixture of the two. Other procedures included lowpass filtering, and a task requiring discrimination between textured figures of different shapes. Orientation cues are weakly or inconsistently used for segregating mesh textures. The low spatial harmonics are very important. A new finding is that orientation and position jitter thresholds for a set of figure/ground texture patterns are often proportional. In a mixture the one disorder can be exchanged for the other.
Area V5 or MT of primate extrastriate visual cortex is specialized for involvement in the analysis of motion and receives input from two layers, 4B and 6, of the striate cortex or V1. Injections of horseradish peroxid...
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Area V5 or MT of primate extrastriate visual cortex is specialized for involvement in the analysis of motion and receives input from two layers, 4B and 6, of the striate cortex or V1. Injections of horseradish peroxidase - wheatgerm agglutinin into V5 reveal a patchy distribution of labelled cells and axonal terminals in layer 4B, suggesting the presence of a segregated and functionally specialized subsystem within the layer. The patches are similar in size and frequency to the cytochrome oxidase blobs of layers 2 and 3, but bear little systematic relationship to them. V5-efferent cells in layer 6, however, tend to avoid the cores of the blobs. The back projection from V5 is continuously distributed in layers 6 and 1, though it is absent inside representations of the central 10° in the latter; it is also diffusely distributed between the patches in layer 4B and over a territory wider than that occupied by labelled cells. It is thus inferred that the back projection probably influences ( a ) V5-efferent cells other than those projecting to the injected site in V5, and ( b ) cells projecting to locations other than V5. There are no major changes in the cortical frequency of V5-efferent cells with eccentricity in the visual field representation. The V5-efferent cells of layer 6 are tenfold less frequent than those of layer 4B and as a population may therefore be involved with only a limited sector of directions of movement. Furthermore, their topographic distribution does not always coincide exactly with that of the layer 4B population, as if a site in V5 receives information about slightly non-corresponding regions of the visual field from the two layers.
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