> I tried to extract the elavation value of a particular location on the SRTM > data i > loaded on my database using the following command SELECT > ST_Value(rast,ST_Point(-106.2,38.6)) AS Elevation From srtm; > > but it only brought out a long elevation column with no value shown. > What could be the issue?
You have to assign a SRID to your point with ST_SetSRID(). If this SRID is not the same as the raster you must then reproject your point using ST_Transform(). > Also If i try to issue a command like this : > > SELECT ST_Value(rast) AS Elevation > From srtm > Where rid = 1304; > > Error message. "function st_value(raster) does not exist" ST_Value is for extracting one value from a raster. What you wrote makes no sense since you are not saying which one to extract... You must specify the x and y of the pixel for which you want a value or pass a geometry point (in the same SRID). Pierre _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
