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Model Description

Model is described by the boundary representation and consists of the following model entities -- vertices, curves, surfaces and regions. Region is formed by a set of not self-intersecting boundary surfaces. Each surface is bounded by a set of curves and stores the regions on the side of its outer and inner normal. Curve is determined by two end vertices and keeps list of surfaces sharing this curve. Vertex stores only the list of associated curves. This basic topology is further restricted by geometry of model entities. Both curves and surfaces are based on free-form representation in terms of tensor product polynomial entities. This limits the number of curves bounding a surface to four. Currently, the rational Bezier entities are employed for free-form curves and surfaces representation. This allows to represent exactly conics and quadrics. To enhance the modeling capability the entity-to-entity fixation concept is introduced. Generally, each model entity may be fixed to another model entity of the same or higher dimension. The fixed entity must coincide with appropriate parametric subentity of parent model entity except the boundary of that parent entity. Each model entity is keeping the list of entities fixed to it. No further topological information are required for description of valid domain of arbitrary complexity.



Next: Mesh Size Control Up: Sequential Mesh Generation Previous: Sequential Mesh Generation

Daniel Rypl
2005-12-03