I am developing a PostGIS query to sample rasters using a point table to detect land cover change. I have read the documentation on ST_value and I am able to get the raster value of a single point using the following query:
SELECT rid, ST_Value(rast, 1, ST_SetSRID(ST_Point(484375.820,4742079.979), 32617)) as b1 FROM imagery.l8_2015_09_12 WHERE ST_Intersects(rast, ST_SetSRID(ST_Point(484375.820,4742079.979), 32617)::geometry, 1);
However, when sampling using a table of points, I cannot get ST_Value to work. When running the following query in the SQL window of QGIS:
-- sample a raster from a table of points SELECT ST_Value(r.rast, 3, p.geom) As band3 FROM analysis_results.sample_points AS p, imagery.l8_2015_09_12 AS r WHERE ST_Intersects(r.rast,p.geom);
I get the following error:
Attempting to get the value of a pixel with a non-point geometry
The table has a multipoint geometry data type, so why is ST_value not playing nicely?