How to make Megascans grass blend with terrain

I’m using some surfaces from Megascans for terrain textures, which works fine enough. I need to add some global variation/distortion to avoid the worst of the tiling, and some larger-scale macro-maps for flying views, but that’s pretty normal.

Then I’m also trying to use some foliage assets for landscape grass, but that doesn’t work so well.

I have tried with and without shadows, and it really doesn’t make much difference. (Shadows are cascaded shadow maps – I’m forcing no precomputed lighting.)

There seem to be two problems:

  1. The “back” side is significantly darker than the “front” side – maybe the subsurface doesn’t work, maybe something else
  2. As soon as I zoom out just a little bit, the meshes turn into flat LOD billboards, which excaberates the effect of 1 dramatically, creating a … salt-and-pepper distribution

The Peter Pan shadows in the distance don’t help, but that’s a separate issue. I could crank up shadow map resolution or number of cascades to make that better.

Is there some trick to get these models working alright. If it matters, these are the Thatching Grass uddmcgbia plants, all 20 of them in one big landscape grass setup.