Deformable Part Models with Individual Part Scaling

Current deformable part models such as the ones introduced by Felzenszwalb et al. let the parts deform only at a fixed predetermined scale relative to that of the root of the models (typically at twice the resolution). They do so because it allows them to find the optimal placement of each part efficiently, using a fast 2D distance transform algorithm. We demonstrate in this paper that if one settles for approximately optimal placements, it is possible to efficiently deform the parts across scales as well. Allowing parts to move in 3D increases the expressivity of the models, allowing them to compensate for a wider class of deformations, and might approximate an increase in the scanning resolution. As the number of parameters remains (nearly) constant, overfitting is not a problem.