A Spatial Index Using MBR Compression and Hashing Technique for Mobile Map Service

Abstract

While the volumes of spatial data are tremendous and spatial operations are time-intensive, mobile devices own limited storages and low computational resources. Therefore, a spatial index for mobile map services should be small and efficiently filter out the candidate objects of a spatial operation as well. This paper proposes a spatial index called MHF(Multilevel Hashing File) for the mobile map service. The MHF has a simple structure for storage utilization and uses a hashing technique for search efficiency. This paper also designs a compression scheme of MBR(Minimum Bounding Rectangle) called HMBR. Although the HMBR scheme reduces the volume of MBR to almost a third, it still achieves a good filtering efficiency because of no information loss by quantization in case of small objects that occupy a major portion. Our experimental tests show that the proposed MHF with HMBR is appropriate for mobile devices in terms of the volume of index, the number of the MBR comparisons, the filtering efficiency and the execution time of spatial operations.