Morphologically Invariant Matching of Structures with the Complete Rank Transform.

Oliver Demetz, David Hafner, Joachim Weickert

Abstract: Invariances are one of the key concepts to render computer vision algorithms robust against severe illumination changes. However, there is no free lunch: With any invariance comes an unavoidable loss of information. The goal of our paper is to introduce two novel descriptors which minimise this loss: the complete rank transform and the complete census transform. They are invariant under monotonically increasing intensity rescalings, while containing a maximum possible amount of information. To analyse our descriptors, we embed them as constancy assumptions into a variational framework for optic flow computation. As a suitable regularisation term, we choose total generalised variation that favours piecewise affine solutions. Our experiments focus on the KITTI benchmark where robustness w.r.t. illumination changes is one of the main issues. The results demonstrate that our descriptors yield state-of-the-art accuracy.