Converting CSG models into meshed B-Rep models using euler operators and propagation based marching cubes

Abstract

The purpose of this work is to define a new algorithm for converting a CSG representation into a B-Rep representation. Usually this conversion is done determining the union, intersection or difference from two B-Rep represented solids. Due to the lack of explicit representation of surface boundaries, CSG models must be converted into B-Rep solid models when a description based on polygonal mesh is required. A potential solution is to convert a CSG model into a voxel based volume representation and then construct a B-Rep solid model. This method is called CSG voxelization, conceptually it is a set membership classification problem with respect to the CSG object for all sampling points in a volume space. Marching cubes algorithms create a simple mesh that is enough for visualization purposes. However, when engineering processes are involved, a solid model is necessary. A solid ensures that all triangles in the mesh are consistently oriented and define a closed surface. It is proposed in this work an algorithm for converting CSG models into triangulated solid models through propagation based marching cubes algorithm. Three main new concepts are used in the algorithm: open boundary, B-Rep/CSG Voxelization mapping and constructive triangulation of active cells. The triangles supplied by the marching cubes algorithm need not be coherently oriented; the algorithm itself finds the correct orientation for the supplied triangles. The proposed algorithm restricts the exploration to the space occupied by the solid's boundary. Differently from normal marching cubes algorithms that explore the complete sampled space

Automatic Creation of Blending Surfaces in Hydropower Generators Turbine Blades

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A Spatial Lattice Model Applied for Meteorological Visualization and Analysis

“…During recent decades, a series of relevant data models were proposed. In summary, there are surface models, e.g., the boundary-represented (B-rep) model and the mesh surface model, that are used to express objects with their surface boundaries [11]; voxel models, e.g., the tetrahedral model and the triangular prism models, that are used to express solid objects with finitely partitioned volumetric units [12][13][14]; and integrated models that combine surface and voxel models together to describe both the surface and internal structure of these geographic objects [15]. With the above models, geographical information concerning space and objects can be described from different perspectives, and they have thus made a considerable contribution to the development of current GISs.…”

Multi-level voxel representation for GPU-accelerated solid modeling

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