General shape distributions in a plane

In this paper the authors investigate the exact shape distribution for general Gaussian labelled point configurations in two dimensions. The shape density is written in a closed form, in terms of Kendall’s or Bookstein’s shape variables. The distribution simplifies considerably in certain cases, including the complex normal, isotropic, circular Markov and equal means cases. Various asymptotic properties of the distribution are investigated, including a large variation distribution and the normal approximation for small variations. The triangle case is considered in particular detail, and the authors compare the density with simulated densities for some examples. Finally, they consider inference problems, with an application in biology.