Filling gaps in the boundary of a polyhedron
Computer Aided Geometric Design
VIS '97 Proceedings of the 8th conference on Visualization '97
RSVP: A Geometric Toolkit for Controlled Repair of Solid Models
IEEE Transactions on Visualization and Computer Graphics
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The proposed approach focuses on the direct use of the triangulation obtained from the digitizing phase to avoid the construction of a CAD model from the digitized points and provide directly the FE model required for the analysis or the adapted geometry required to generate the FE mesh.A first step analyses the input triangulation to check its conformity and correct it to remove degenerate faces, unwanted gaps, self intersecting areas that can be generated during the generation phase of this input triangulation. Most of these operations are automated through specific operators to ease the generation of a conform triangulation and tools are provided to analyze the conformity of this triangulation.Depending on the digitizing technique (3D laser sensor, tomography), complementary operators may be applied to generate an adequate initial triangulation and the FE model generation may requires two distinct stages to produce the adapted model and then the FE mesh generation. A two stages approach is required when detail removal operations are required with respect to the desired analysis model.In this case, the first stage is used to perform noise and detail removal from the input triangulation. Noise is inherited from the scanning phase and needs to be removed to produce a smooth triangulation. This operation is performed using a shape preserving decimation algorithm based on a vertex removal operator. The maximum geometric deviation between the initial triangulation and the smoothed one is controlled by a distance criterion. From this triangulation a detail removal process takes place to adapt the object geometry to the hypotheses of the analysis and the requirements of the FE mesh.Then, the second stage is the generation of the FE mesh onto the adapted triangulation representing the domain of study.In order to speed up further the process the first and second stages described above can be merged together when the geometry adaptation phase does not need to large geometry changes or topological changes. In this configuration, a single process used to remove the digitizing noise, perform surface adaptation of the part and generate the target FE mesh can be directly applied on the conform triangulation. Finally, results are provided for historical structures and industrial parts.