Fitting Freeform Shape Patterns to Scanned 3D Objects

Abstract

This paper describes a new approach to locate freeform shape patterns in measured point data and to fit their parameter values. The method is based on the direct matching of parameterized shape templates to digitized points. For a given class of feature, the optimal pose and the optimal intrinsic shape parameters are determined. Although this principle was previously used in digital image processing and also for fitting of regular shaped features, it has rarely been applied in 3D to freeform features. Yet, several engineering applications may profit from improved feature fitting. The motivation of our investigation is to enable the reuse of precedent shapes, available in the form of physical parts. We aim at an extension to what is generally known as reverse engineering of shape. However, the proposed technique can also be used to extract feature parameters from imported CAD models. This paper addresses computational aspects of the method and presents the algorithms, implementation tests and numerical results.