PSLSH: An Index Structure for Efficient Execution of Set Queries in High-Dimensional Spaces.

Efficient implementations of range and nearest neighbor queries are critical in many large multimedia applications. Locality Sensitive Hashing (LSH) is a popular technique for performing approximate searches in high-dimensional multimedia, such as image or sensory data. Often times, these multimedia data are represented as a collection of important spatio-temporal features which are extracted by using localized feature extraction algorithms. When a user wants to search for a given entity (object, event, or observation), individual similarity search queries, which collectively form a set query, need to be performed on the features that represent the particular search entity. Existing LSH techniques require that users provide an accuracy guarantee for each query in the set query, instead of an overall guarantee for the entire set query, which can lead to misses or wasteful work. We propose a novel index structure, Point Set LSH (PSLSH), which is able to execute a similarity search for a given set of search points in the high-dimensional space with a user-provided guarantee for the entire set query. Experimental evaluation shows significant gains in efficiency and accuracy trade-offs for executing set queries in high-dimensional spaces.