The ANN-tree: An Index for Efficient Approximate Nearest Neighbor Search

In th is paper we explore t h e problem of approximate nearest neighbor searches. W e propose a n i n d e x structure, t h e A N N t r e e (approximate nearest neighbor tree) t o solve this problem. T h e A N N t r e e supports high accuracy nearest neighbor search. T h e actual nearest neighbor of a query poin t can usually be f o u n d in the f i r s t leaf page accessed. T h e accuracy increases t o near 100% if a second page is accessed. T h i s i s n o t achievable via traditional indexes. E v e n if a n exact nearest nearest neighbor query is desired, t h e A N N t r e e i s demonstrably m o r e eff icient t h a n existing structures like t h e R *-tree. This m a k e s the A N N t r e e a preferable i n d e x structure f o r both exac t and approximate nearest neighbor searches. W e present the i n d e x in detail and provide experimental results o n both real and syn the t ic