Hi Tony, I'm sorry I'm not quite sure what you mean by a "pattern of light in which you put on a nurbs texture of grass", could you maybe describe that some more?

But it's hard to get a good appearance of grass just by a flat texture map. I think for best results you don't even want to use a displacement map for it - you want to have actual polygon geometry created for the grass but for things like that it's better to have the geometry created by an automated mechanism that will generate the geometry according to some parameters that you give it. That's how a hair or fur rendering system will usually work.

- Michael