Likelihood Models For Template Matching using the PDF Projection Theorem

Template matching techniques are widely used in many computer vision tasks. Generally, a likelihood value is calculated from similarity measures, however the relation between these measures and the data likelihood is often incorrectly stated. It is clear that accurate likelihood estimation will improve the efficiency of the matching algorithms. This paper introduces a novel method for estimating the likelihood PDFS accurately based on the PDF Projection Theorem, which provides the correct relation between the feature likelihood and the data likelihood, permitting the use of different types of features for different types of objects and still estimating consistent likelihoods. The proposed method removes the normalization and bias problems that are usually associated with the likelihood calculations. We demonstrate that it significantly improves template matching in pose estimation problems. Qualitative and quantitative results are compared against traditional likelihood estimation schemes.