There seems to me to be a bug in the "Ray traced shadows" setting of the renderer. Attached are three images of a terrain I'm working on, a DEM. In the first image, a heighfield erode has been applied, and these very dark shadows on the terrain showed up when I switched on ray traced shadows (in order to get the tree shadows). I removed the erode, but the shadows remain(#2). Finally, removed all surface layers and objects (#3). Still there.
I could understand that the terrain would cast shadows on itself, which is what I presume is happening. What I can't fathom is why the shadows are so dark. Even when I ramp up GI on surfaces to the absurdly unrealistic 10.5, they are still visible (#4).
Does anyone have a clue what's happening here? These shadows spoil the scene, so I'm keen to resolve it. I haven't attached a TGD, as the terrain is an 8MB DEM, but I can email it to PS or others if it's needed for diagnosis.