Reconstruction Techniques, Based On The Sketch Profile Of The Feature Model. Reverse Engineering

The research on constraints based structural feature model reconstruction method is a new aspect in reversing engineering, which can be used to reconstruct more reliable model. Modeling in current 3D CAD softwares such as CATIA, Pro/Engineer are mainly based on sketch design.According to the idea of modeling and on the basis of segmenting 3D measured data with feature design intention, this thesis studies the reconstruction methods of model sketch-based feature such as extruded and rotational features in structural part models. The main contents of this thesis are as follows:(1) The technique of sketch profile fitting is studied in this thesis. First the sketch/datum plane is fitted by Least-Square distance,then the extruded direction or axis with the flank points of the cloud is extracted in quadratic paogramming arithmetic, and certain points projected to gain 2D sketched datas. Feature points are defined to segment the sketch datas,and the sketch profile is generated by fitting separately the line and circle segment.(2) The 2D geometry constraints between or among the features are classified. The expressions of 2D constrains and the resolvent about constraints are discussed,and the algorithms and process of resolving constraints are demonstrated.(3) The generation methods of sketch-based feature model reconstruction are presented in this thesis. Experimental results show that the methods presented here are reliable.(4) This thesis also gives a brief introduction to CATIA developing platform (CAA) and the arithmetics mentioned in this paper.