This paper approaches the problem of finding correspondences between
images in which there are large changes in viewpoint, scale and illumination. Recent work has shown that scale-space ‘interest points’ may
befound with good repeatability in spite of such changes. Furthermore, the high entropy of the surrounding image regions means that
local descriptors are highly discriminative for matching. For descriptors at interest points to be robustly matched between images, they
must be as far as possible invariant to the imaging process.
In this work we introduce a family of features which use groups
of interest points to form geometrically invariant descriptors of image
regions. Feature descriptors are formed by resampling the image relative to canonical frames defined by the points. In addition to robust
matching, a key advantage of this approach is that each match implies
ahypothesis of the local 2D (projective) transformation. This allows
us to immediately reject most of the false matches using a Hough transform. We reject remaining outliers using RANSAC and the epipolar
constraint. Results show that dense feature matching can be achieved
in a few seconds of computation on 1GHz Pentium III machines.