Implementing a culling and self-intersection algorithm for stereolithography files in Ada 95

Abstract

1. ABSTRACT Given coordinate information for a triangulated three-dimensional object, and given that we are able to move one of the object’s vertices, we wish to determine whether or not the vertex movement has inadvertently introduced a self-intersection within the object. This problem is relevant to the stereolithography domain, where threedimensional objects may be specified with triangular facets, and rapidly fabricated with a laser and liquid polymer. We developed and implemented an algorithm in Ada 95 that determines whether or not a self-intersection has been introduced to an object, along with a corresponding culling algorithm. The culling process that allow us to resolve the selfintersection question quickly, even in an object with thousands of vertices and facets. 1.1