9.34. Geometry Data Types and Spatial Index Support
Virtuoso includes a spatial database capability from version 6.01.3126 onwards. This capability is specially geared towards geographical data in RDF but can be used with SQL also. The functions implemented follow the SQL MM spatial specification where applicable but the entire SQL MM function set is not supported.
Spatial indexing is supported by a two dimensional R tree implementation. The geometries supported may have from two to four dimensions, with a choice of WGS 84 (or similar) latitude and longitude coordinates with haversine distances or a flat 2 dimensional plane for spatial reference system.
9.34.1. Spatial References
The default reference system is WGS-84 with coordinates in degrees of longitude and latitude on
Earth. The SRID number for this is 4326 and is assigned by default to all new geometries.
ST_Transform
can be used to re-calculate coordinates of a shape from one spatial reference system to another.
ST_SetSRID
can be used for altering SRID without altering coordinates.
Distances and precisions for "latitude-longitude" spatial reference systems are in kilometers, as approximately calculated with the haversine formula. For other systems they are in the same unit as the coordinates.