Illumination and Affine- Invariant Point Matching using an Ordinal Approach

We present an approach for illumination and affine-invariant point matching using ordinal features. Ordinal measures for matching only consider the order between pixels and not the absolute intensity values which enables them to be invariant to a monotonic change in intensities. The utility of such measures has been demonstrated in the past for point matching for some applications such as background subtraction and stereo matching. However, invariance of such methods to geometric transformations has been limited leading to their inapplicability for more generic matching applications such as object recognition, wide-baseline stereo matching, mosaicing or tracking points on moving objects. In this paper, we extend such methods for use in such applications. The method is invariant to an affine transformation in the patch, which makes it applicable to a variety of applications. At the same time, our method is robust to different types of noise processes possible in a real scene. Experiments indicate favorable performance when compared to other state-of-the-art methods for affine-invariant point matching.