ROR: Rejection of outliers by rotations

We address the problem of rejecting false matches of points between two per spective views. The two views are taken from two arbitrary, unknown positio ns and orientations. Even the best algorithms for image matching make some mistakes and output some false matches. We present an algorithm for identif ication of the false matches between the views. The algorithm exploits the possibility of rotating one of the images to achieve some common behavior o f the correct matches. Those matches that deviate from this common behavior turn out to be false matches. Our algorithm does not, in any way, use the image characteristics of the matched features. In particular, it avoids pro blems that cause the false matches in the first place. The algorithm works even in cases where the percentage of false matches is as high as 85 percen t. The algorithm may be run as a postprocessing step on output from any poi nt matching algorithm. Use of the algorithm may significantly improve the r atio of correct matches to incorrect matches. For robust estimation algorit hms which are later employed, this is a very desirable quality since it red uces significantly their computational cost. We present the algorithm, iden tify the conditions under which it works, and present results of testing it on both synthetic and real images. The code for the algorithm is available through the World Wide Web.