Walking around fat obstacles

We prove that if an object O is convex and fat then, for any two points a and b on its boundary, there exists a path on O's boundary, from a to b, whose length is bounded by the length of the line segment ab times some constant β. This constant is a function of the dimension d and the fatness parameter. We prove bounds for β, and show how to efficiently find paths on the boundary of O whose lengths are within these bounds. As an application of this result, we briefly consider the problem of efficiently computing short paths in Rd in the presence of disjoint convex fat obstacles.