I would suggest generating erosion on the terrain using a dedicated tool like WorldMachine or Terragen or the like. This will make a splat map for you, which you can use in a Composite node as your layer masks. To isolate the RGB color channels you can use Color Correction nodes, or even easier just use a single OSL Uber…
How common are the dedicated postitions in the games industry? I know smaller studios probably won't have a person dedicated to lighting, and even the more bigger studios seem have a smaller section dedicated to it, if any. Whats the best way to show off a portfolio regarding a lighting artist? Do I need to light full…