On Fri, Dec 2, 2011 at 8:15 AM, Stefan Keller <sfkel...@gmail.com> wrote: > In a server side program I'd like to get the height given a 2D lat/lon > coordinate. > > The area covered is smaller than Europe with a resolution of at least > 25m. We'll take ASTER or SRTM as DEM/DTM data. > > I know there are webservices like geonames' Elevation API (e.g. > http://api.geonames.org/astergdem?lat=50.01&lng=10.2&username=demo ). > But I'd like to know if this is feasible using PostgreSQL. > > Is PostGIS Raster efficient enough to process and query such an amount of > data? > Any experiences? >
Stefan, Assuming you test to see what the ideal (or "good-enough") tile size is for the elevation rasterset, you should see good performance using ST_Value(rast, ST_SetSRID(ST_MakePoint(long, lat), srid)) You could eliminate the ST_SetSRID and ST_MakePoint by passing a correct EWKT instead ST_Value(rast, 'YOUREWKT'::geometry) The question of tile size comes because the serialized raster data is stored in TOAST, which may compress the data. -bborie -- Bborie Park Programmer Center for Vectorborne Diseases UC Davis 530-752-8380 bkp...@ucdavis.edu _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
