Spherical Geometry Toolkit with HTM
This is core engine that deals with sky coverage and footprints.
The Spherical Library provides an efficient and accurate mathematical
representation of shapes on the celestial sphere. Shapes of arbitrary
complexity and size can be dynamically created from simple building blocks,
whose exact area is also analytically computed.
The Hierarchical Triangular Mesh (HTM) builds our new spherical geometry
routines to speed up spatial searches. Both toolkits come with wrappers
that provide extensions to SQL Server for all database users. If you
ever queried the SDSS, GALEX, HLA or the UKIDSS archives, chances are that
you have used these SQL routines.