Default interaction raycasts need to ignore terrain

Believe it or not. Morrowind.exe doesn't include the terrain when doing basic interaction raycasts. You can pick up the ebony shortsword buried under Odai Plateau in Morrowind.exe but not in OpenMW.

This is a mod compatibility problem: there are mods that have "buried treasure" that's barely visible from above ground, by a couple pixels, but are easy to interact with in Morrowind.exe.

Care should be taken to decide whether this behavior should translate to other parts of the engine (like Lua raycasts). My default assumption is "no", it should only affect default built-in interaction raycasts.