iSPEED: an Efficient In-Memory Based Spatial Query System for Large-Scale 3D Data with Complex Structures.

Recent advances in digital pathology make it possible to support 3D tissue-based investigation of human diseases at extremely high resolutions. Exploring spatial relationships and patterns among massive 3D micro-anatomic biological objects such as blood vessels and cells derived from 3D pathology image volumes plays a critical role in studying human diseases. In this paper, we present our work on building an effective and scalable in-memory based spatial query system iSPEED for large-scale 3D data with complex structures. To achieve low latency, iSPEED stores data in memory with effective progressive compression for each 3D object with successive levels of detail. To minimize search space and computation cost, iSPEED pregenerates global spatial indexes in memory and employs on-demand indexing at run-time. In particular, iSPEED exploits structural indexing for complex structured objects in distance based queries. iSPEED provides a 3D spatial query engine that can be invoked on-demand to run many instances in parallel implemented with, but not limited to, MapReduce. iSPEED builds in-memory indexes and decompresses data on-demand, which has minimal memory footprint. We evaluate iSPEED with two representative queries: 3D spatial joins and 3D spatial proximity estimation. Our experiments demonstrate that iSPEED significantly improves the performance over traditional non-memory based spatial query systems.