Factored Shapes and Appearances for Parts-based Object Understanding

We present a novel generative framework for learning parts-based representations of object classes. Our model, Factored Shapes and Appearances (FSA), employs a highly factored representation to reason about appearance and shape variability across datasets of images. We propose Markov Chain Monte Carlo sampling schemes for efficient inference and learning, and evaluate the model on a number of datasets. Here we consider datasets that exhibit large amounts of variability, both in the shapes of objects in the scene, and in their appearances. We show that the FSA model extracts meaningful parts from training data, and that its parameters and representation can be used to perform a range of tasks, including object parsing, segmentation and fine-grained categorisation.