The matching and retrieval of 2D shapes is an important
challenge in computer vision. A large number of shape
similarity approaches have been developed, with the main
focus being the comparison or matching of pairs of shapes.
In these approaches, other shapes do not influence the similarity
measure of a given pair of shapes. In the proposed approach,
other shapes do influence the similarity measure of
each pair of shapes, and we show that this influence is beneficial
even in the unsupervised setting (without any prior
knowledge of shape classes). The influence of other shapes
is propagated as a diffusion process on a graph formed
by a given set of shapes. However, the classical diffusion
process does not perform well in shape space for two reasons:
it is unstable in the presence of noise and the underlying
local geometry is sparse. We introduce a locally constrained
diffusion process which is more stable even if noise
is present, and we densify the shape space by adding...