Construction of an Approximate 3D Orthogonal Convex Skull

Orthogonal convex skull of a 3D digital object is a maximal volume orthogonal convex polyhedron lying entirely inside the object. An efficient combinatorial algorithm to construct an approximate 3D orthogonal convex skull of a digital object is presented in this paper. The 3D orthogonal inner cover, an orthogonal polyhedron which tightly inscribes the digital object, is divided into slab polygons and 2D orthogonal skulls of these slab polygons are combined together using combinatorial techniques to obtain an approximate 3D orthogonal convex skull. The algorithm operates in integer domain and requires at most two passes. The current version of the algorithm deals with non-intersecting objects free from holes and cavities. Experimentation on a wide range of digital objects has provided expected results, some of which are presented here to demonstrate the efficacy of the algorithm.