I'd like to create a raster from point data, averaging the point data over a given area and placing the results into a given pixel/cell. With each pixel/cell as 50m x 50m.
I'm new to this and have a beginner question.
I see that in PostGIS 2.0 there is a ST_MakeEmptyRaster() function, but what are the units for width, height, and pixelsize. And how do you determine the upperleftx, upperlefty points? Is this just random, or is there a convention used to determine this point?
raster ST_MakeEmptyRaster(integer width, integer height, float8 upperleftx, float8 upperlefty, float8 pixelsize);