Automatic Feature-Based Sampling of Native CAD Data for Surface Grid Generation

An automatic feature-based sampling of native CAD data (NASA-IGES, STEP, FLITE) is presented together with applications. The user only specifies a minimal and maximal allowed length and a maximal allowed curvature angle for the complete geometry or rather parts of it. Now locally the curvature of the CAD curve or rather CAD surface is computed, which defines a local length depending on the input parameters. This local length cannot be larger than the length of the corresponding CAD curve or rather CAD surface. Therewith, a length distribution is obtained fully automatically for the complete geometry. A locally refined Cartesian background mesh (octree data-structure) is constructed based on the length distribution, which stores and smoothes the local lengths. Afterwards the triangulation is generated by an advancing front triangulator: the local resolution of the surface triangulation depends on the mesh size specification, which is given by the locally refined Cartesian mesh. The sampling program takes benefit of the object-oriented design and implementation (programming language C++) and is parallized for computer systems with distributed memory using message passing (MPI).