Combining discriminative and model based approaches for hand pose estimation

In this paper we present an approach to hand pose estimation that combines both discriminative and modelbased methods to overcome the limitations of each technique in isolation. A Randomised Decision Forests (RDF) is used to provide an initial estimate of the regions of the hand. This initial segmentation provides constraints to which a 3D model is fitted using Rigid Body Dynamics. Model fitting is guided using point to surface constraints which bind a kinematic model of the hand to the depth cloud using the segmentation of the discriminative approach. This combines the advantages of both techniques, reducing the training requirements for discriminative classification and simplifying the optimization process involved in model fitting by incorporating physical constraints from the segmentation. Our experiments on two challenging sequences show that this combined method outperforms the current state-of-the-art approach.