ST_AsRaster for polygon

Question

Having a hard time to get a raster from a polygon

ST_AsRaster(ST_Buffer(ST_GeomFromText('POLYGON((-30 40, -20 30, -25 20, -23 10, -30 40))', 4326), 50),ARRAY['8BUI'],ARRAY[118]);

This line is giving me an error : No function matches the given name and argument types. You might need to add explicit type casts.

Answer 1

You are missing pixel dimensions:

CREATE EXTENSION IF NOT EXISTS postgis_raster;

SELECT ST_AsRaster(
   ST_Buffer(ST_GeomFromText('POLYGON((-30 40, -20 30, -25 20, -23 10, -30 40))', 4326), 50),
   100,            -- width 
   100,            -- height
   ARRAY['8BUI'],  -- pixeltype
   ARRAY[118]      -- value
 ); -- using ST_AsRaster signature (geometry,int,int,text[],float[])

In this example you can use also the signature (geometry,int,int,text,float).