Tailored Bregman Ball Trees for Effective Nearest Neighbors

Nearest Neighbor (NN) search is a crucial tool that remains critical in many challenging applications of computational geometry (e.g., surface reconstruction, clustering) and computer vision (e.g., image and information retrieval, classification, data mining). We present an effective Bregman ball tree [5] (Bb-tree) construction algorithm that adapts locally its internal node degrees to the inner geometric characteristics of the data-sets. Since symmetric measures are usually preferred for applications in content-based information retrieval, we furthermore extend the Bb-tree to the case of symmetrized Bregman divergences. Exact and approximate NN search experiments using high-dimensional real-world data-sets illustrate that our method improves significantly over the state of the art [5], sometimes by an order of magnitude.