Technology and implement process of feature recognition based on STEP

Aiming at recognizing features from different 3D CAD models, this paper described the implementation process of feature recognition based on STEP. First, an object oriented method was introduced. The predefined feature was presented using object of class instead of attribute table so the code reusability of the feature recognition system can be improved. Second, the mapping relationship of STEP data type and C++ structure was established. So the topological-geometrical tree can be extracted from STEP-based neutral file. According to the topological and geometrical representation of STEP, it recognized the type and geometric parameter of topological layer including face and loop. At last, it recognized the predefined feature by attribute adjacent graph decomposition using sub-graph matching and base-face decomposition method.