We present a shape-based algorithm for detecting and
recognizing non-rigid objects from natural images. The existing
literature in this domain often cannot model the objects
very well. In this paper, we use the skeleton (medial
axis) information to capture the main structure of an object,
which has the particular advantage in modeling articulation
and non-rigid deformation. Given a set of training
samples, a tree-union structure is learned on the extracted
skeletons to model the variation in configuration. Each
branch on the skeleton is associated with a few part-based
templates, modeling the object boundary information. We
then apply sum-and-max algorithm to perform rapid object
detection by matching the skeleton-based active template to
the edge map extracted from a test image. The algorithm
reports the detection result by a composition of the local
maximum responses. Compared with the alternatives on
this topic, our algorithm requires less training samples. It
is si...