Osprey: a heterogeneous search framework for spatial-temporal similarity

In this paper, a heterogeneous spatial-temporal similarity search framework is proposed, in which the datasets come from multiple different asynchronous data sources. Due to measuring error, data loss, and other factors, the similarity search based on single points along a trajectory usually cannot fulfill the accuracy requirements in our heterogeneous case. To address this issue, we introduce a concept of the spatial-temporal cluster of points, instead of single points, which can be identified for each target query. By following this concept, we further design a spectral clustering algorithm to construct the clusters in the pre-processing phase effectively. And the query processing is improved for the accuracy of the search by unifying multiple search metrics. To validate our idea, we also prototype a clustered online spatial-temporal similarity search system, "Osprey", to calculate in parallel the similarity of spatial-temporal sequences in the heterogeneous search on a distributed database. Our empirical study is conducted based on an open dataset, called "T-Drive", and a billion-scale dataset consisting of WiFi positioning records gathered from the urban metro system in Shenzhen, China. The experimental results show that the latency of our proposed system is less than 4s in most cases, and the accuracy is more than 70% when the similarity exceeds 0.5.