2007/01/26 by Alexander S. Szalay, Jim Gray, Szalay, Alexander S. +9 · 5 citations
Computer Science · Engineering · Social Sciences · #Automated Road and Building Extraction #Data Management and Algorithms #Data Structures and Algorithms (cs.DS) #Databases (cs.DB) #FOS: Computer and information sciences #Geographic Information Systems Studies
paper · pdf · doi:10.48550/arxiv.cs/0701164
openalex publication_date 2007/01/26 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We describe a method to subdivide the surface of a sphere into spherical triangles of similar, but not identical, shapes and sizes. The Hierarchical Triangular Mesh (HTM) is a quad-tree that is particularly good at supporting searches at different resolutions, from arc seconds to hemispheres. The subdivision scheme is universal, providing the basis for addressing and for fast lookups. The HTM provides the basis for an efficient geospatial indexing scheme in relational databases where the data have an inherent location on either the celestial sphere or the Earth. The HTM index is superior to cartographical methods using coordinates with singularities at the poles. We also describe a way to specify surface regions that efficiently represent spherical query areas. This article presents the algorithms used to identify the HTM triangles covering such regions.