On the approximation of the Riemannian barycenter

Abstract: We present a method to compute an approximate Riemannian barycenter of a collection of points lying on a Riemannian manifold. Our approach relies on the use of theoretically proven under- and overapproximations of the Riemannian distance function. We compare it to the exact computation of the Riemannian barycenter and to an approach that approximates the Riemannian logarithm using lifting maps. Experiments are conducted on the Stiefel manifold.