Measuring the Affine Transform Using Gaussian Filters

Image deformations due to relative motion between an observer and an object may be used to infer 3-D structure. Up to rst order these deformations can be written in terms of an aane transform. Here, a novel approach is adopted to measuring aane transforms which correctly handles the problem of corresponding deformed patches. The patches are ltered using gaussians and derivatives of gaussians. The problem of nding the aane transform is reduced to that of nding the appropriate deformed lter to use. The method is local and can handle arbitrarily large aane deformations. Experiments demonstrate that this technique can nd scale changes and optical ow in situations where other methods fail.