Information Exchange Of Three-Dimensional Boundary Model Based On Geometric Kernel

The data exchange between 3D-CAD systems is an important component of a CAD system, at the same time, it is a difficulty. The data exchange concerns the data share among different CAD systems; it also has significance to the application and popularizing of home 3D-CAD system. So the research to data exchange between 3D-CAD systems has important applied value.At present, the methods for information exchange between CAD software systems are as follows: the method using special document interface, the method using neutral file of standard common interface, the method using the software geometry core for direct interface. The development and the existing problems of the data exchange using special interface and common interface are deeply discussed in this thesis. At the same time, the development of the direct interface method is described.The direct interface method in this thesis is built on the fact that CAD software system is mostly ParaSolid or ACIS as geometric core and adopts data exchange interface algorithm based on Brep to complete the data exchange.This thesis based on JhSolid software development environment and Visual C++ development tool on Windows platform, using object-oriented technology, through the API functions provieded by DWGdirect and ParaSolid, implements data exchange of border information in three-dimensional model.First of all, in order to obtain ACIS three-dimensional solid model of the Brep information, the topology tree top-down from the ACIS three-dimensional solid model having DWG format preserved by AutoCAD is traversed, and geometric data for the geometric data associated with the topology entity is extracted. And then the geometry and topology mapping relations between three-dimensional solid model of ACIS and ParaSolid is established. According to the ACIS topology traversed, through the API functions provided by kernel ParaSolid topology entities are constructed, then the corresponding geometric entities are created. Finally, through the operation that associates with the geometry and topology entity an integrated and effective ParaSolid entity is generated, and the transformation from ACIS boundary model data to ParaSolid model data is realized. Through coding, debugging and testing on JhSolid software platform, the goal expected has been achieved, and the feasibility of the algorithm, correctness of the programs have been verified.