LOCALIZATION AND COMPARISON OF 2 FREE-FORM SURFACES

Comparison of two free-form surfaces based on discrete data points is of paramount importance for reverse engineering. It can be used to ass ess the accuracy of the reconstructed surfaces and to quantify the dif ference between two such surfaces. The entire process involves three m ain steps: data acquisition, 3D feature localization and quantitative comparison. This paper presents models and algorithms for 3D feature l ocalization and quantitative comparison. Complex free-form surfaces ar e represented by bicubic parametric spline surfaces using discrete poi nts. A simple yet effective pseudoinverse algorithm was developed and implemented for localization. It consists of two iterative operations, namely, constructing a pseudo transformation matrix and point matchin g. A computing algorithm was developed to compare two such surfaces us ing optimization techniques. Since this approach does not involve solv ing non-linear equations for the parameters of positions and orientati ons, it is fast and robust. The algorithm was implemented and tested w ith several examples. It is effective and can be used in industry for sculptured surface comparison. Copyright (C) 1996 Published by Elsevie r Science Ltd