I am currently working on a solar potential estimation tool for existing buildings. The idea is to use buildings (=Polygon) shape, their height, and create the resulting shade at a given hour. I am only going to do the test for a few position of the sun. I know about the grass function r.sun.mask but it is overpowered for what I am trying to do.
For now I only want to get the shade when the sun is south, at 18° in the sky. The building should therefore cast a shadow about three times its height.
What I am trying to get:
I have been looking for a while but I did not find any tool in postgis to do this. I was thinking about buffering and then cutting the polygon but could not make it work. Do you know any tool or have any idea how to do it?