PostGIS raster's goal is to implement the raster type as much as possible like the geometry type is implemented in PostGIS and to offer a single set of overlay SQL functions (such as ST_Intersects
) operating seamlessly on vector and raster coverages.
Each raster or raster tile is stored as a row of data in a PostgreSQL database table. It is a complex type, embedding information about the raster itself (width, height, number of bands, pixel type for each band, and no data value for each band) along with its geolocalization (pixel size, upper left pixel center, rotation, and SRID). These metadata are accessible by raster_columns
view.
Something that shows flexibility of PostGIS raster support is in-db / out-db raster tile storage. Operations on these are identical, no matter if the raster is stored internally in PostgreSQL or file in filesystem. The only drawback is query processing time for out-db raster coverages.
PostGIS Raster is expressed in different...