About vocabulary tree

A vocabulary tree is a hierarchical-structured tree that can efficiently integrate quantization and classification . Object recognition is one of the core problems in computer vision, and it is a very extensively investigated topic. Due to appearance variabilities caused for example by non-rigidity, background clutter, differences in viewpoint, orientation, scale or lighting conditions, it is a hard problem. One of the important challenges is to construct methods that scale well with the size of the database, and can select one out of a large number of objects in acceptable time. For each cluster a vocabulary tree is build for searching the most similar view . Vocabulary tree is usually used to quantize SURF into more compact features