I had already taken a guess and put the alpha on the density channel and it worked as I expected. That is, grass where white is, no grass where black is.
I’ve managed to increase my render time exponentially… definitely must look into building a new machine for this 🙂
What would be the difference if I put the alpha map on length?
And… it is working really well… I’ll post a pic later, but any ideas on making weeds?
Joe