@masterq, I wonder if there might be a way to detect the sillouette in screenspace and place some of the mesh at the end of the distant sillouette to get rid of the straight lines in the horizon from the polygons.

originally I thought of something like in Rome Total War, I mean the 10 year old version, not the new RTW2, where on close distance you can see very simple fur-like grass blades (on high graphics settings they recieve shadows):

in the following edition, Medieval Total War 2, there are grass models used I think, during playing it can be seen that they are not billboards, and appearing in groups similarly if I place grass models consisting of severasl sprite like plates in 3dgs:

as I remeber Heelx put a link to this forum of an article decribing vegetation shaders used in a AAA game, but I do not really understand that.