Raster-spatial data declustering revisited: an interactive navigation perspective

Various declustering techniques have been proposed in the literature for raster-geospatial data. Their primary focus is on reducing response time for static range queries. We focus on interactive navigation queries, which exhibit a new class of data access patterns. We analyze and compare the performance of three well-known declustering schemes: Disk Modulo, Exclusive-OR, and Hilbert Curve Access Method. The results show that Disk Modulo is close to optimal and, contrary to the case of range queries, is significantly better than Hilbert Curve Access Method. In addition, we propose a new scheme that further improves Disk Module for a realistic situation when the navigation window is bounded by a maximum size-a common constraint due to either monitor resolution or limited memory size. Performance properties of the scheme are also analyzed.