Avoiding the “Streetlight Effect”: Tracking by Exploring Likelihood Modes

Classic methods for Bayesian inference effectively constrain search to lie within regions of significant probability of the instantaneous temporal prior. This is efficient with an accurate dynamics model, but otherwise is prone to ignore significant peaks in the true posterior. A more accurate posterior can be obtained by explicitly finding modes of the likelihood function and combining them with an approximate temporal prior. In our approach modes are found using efficient example-based matching followed by local refinement to find peaks and estimate peak bandwidth. By reweighting these peaks according to the temporal prior we obtain an estimate of the full posterior model. We show comparative results on real and synthetic images in a high d.o.f. articulated tracking task.