Fast Slicing of Orthogonal Covers Using DCEL

A combinatorial algorithm to find the intersection of an axis-parallel slicing plane with the orthogonal cover of a digital object is presented in this paper. The orthogonal cover is the smallest-volume 3D orthogonal polyhedron containing the object and stored in a doubly connected edge list (DCEL). Its intersection with the slicing plane consists of one or more isothetic polygons that provide topological information about the cover. The algorithm traverses the vertices on the polyhedron boundary and lying on the slicing plane, and the direction of next move from a vertex is determined by a set of linear equations in the integer domain. Results for few objects with successive slicing planes are presented to demonstrate the effectiveness and elegance of the algorithm.