Maximizing the overlap of two planar convex sets under rigid motions

Abstract

Given two compact convex sets P and Q in the plane, we compute an image of P under a rigid motion that approximately maximizes the overlap with Q. More precisely, for any epsilon > 0, we compute a rigid motion such that the area of overlap is at least 1-epsilon times the maximum possible overlap. Our algorithm uses O(1/epsilon) extreme point and line intersection queries on P and Q, plus O((1/epsilon(2)) log(1/epsilon)) running time. If only translations are allowed, the extra running time reduces to O((1/epsilon) log(1/epsilon)). If P and Q are convex polygons with n vertices in total that are given in an array or balanced tree, the total running time is O((1/epsilon) log n + (1/epsilon(2)) log(1/epsilon)) for rigid motions and O((1/epsilon) log n + (1/epsilon) log(1/epsilon)) for translations. (c) 2006 Elsevier B.V. All rights reserved.