Does Landscape contribute to global distance field?

4.12 has:

  • Landscape is now in the global distance field. Distance is computed with an approximation - the heightfield is sampled once directly below and a plane is constructed from that height + normal. The distance is computed from this plane. It works well unless there’s significant curvature in the landscape below where you’re trying to use the global distance field.
  • Control over the MaxOcclusionDistance of the global distance field in WorldSettings. Increasing this makes the global distance field cost a lot more to compute though! If using the gradient you should fade its contribution out based on DistanceToNearestSurface.
  • Control over how far from the camera the global distance field will cover, in WorldSettings.

Would it be technically possible to allow landscape height map sampling without using distance fields?

Sadly, not with the current implementation - the landscape heightfield is broken up into a bunch of different textures to support texture streaming.