Common-Frame Model for Object Recognition

Abstract

A generative probabilistic model for objects in images is presented. An object consists of a constellation of features. Feature appearance and pose are modeled probabilistically. Scene images are generated by draw- ing a set of objects from a given database, with random clutter sprinkled on the remaining image surface. Occlusion is allowed. We study the case where features from the same object share a common reference frame. Moreover, parameters for shape and appearance den- sities are shared across features. This is to be contrasted with previous work on probabilistic `constellation' models where features depend on each other, and each feature and model have different pose and appear- ance statistics [1, 2]. These two differences allow us to build models containing hundreds of features, as well as to train each model from a single example. Our model may also be thought of as a probabilistic revisitation of Lowe's model [3, 4]. We propose an efficient entropy-minimization inference algorithm that constructs the best interpretation of a scene as a collection of objects and clutter. We test our ideas with experiments on two image databases. We compare with Lowe's algorithm and demonstrate better performance, in particular in presence of large amounts of background clutter.