When trying to render grass on a vertical surface, the 3D quality of the material disappears and essentially turns into an image of grass. This happens once you apply a grass material to anything more that a 70 degree incline. It would be nice to be able to render it on a vertical surface for grass walls.
Also frosted glass seems to always be an issue. The glass will look very transparent at anything below 6% or lower transparency (Revit), but far too opaque at anything above 6%. For some reason 6% is the magic number between completely transparent and completely opaque. This should be a sliding scale of transparency.