I've had a bit of time to check out some of the new features of Max 9, and one of the best ones I've seen yet is the inclusion of the Hair & Fur modifier (at least I think it's new to Max 9...).
I've looked and searched and scoured for different methods of easily creating realistic grass but, aside from creating bent triangles and scattering them around, haven't found anything worth using on a consistent basis.
Then, last night, I discovered this wonderful modifier.
With little tweaking, the Hair & Fur modifier creates beautiful grass whose appearance and tones are able to be adjusted, and on top of that, it's fully capable of being animated.
1. Create a plane. Size isn't so much a factor, as the object that has the modifier can be any size or shape, but for the purpose of this tutorial, keep it relatively small.
2. Apply a white material to the plane and to the environment. This isn't necessary, but it helps to see the effects of the modifier.
3. With the plane selected, add the "Hair and Fur [WSM]" modifier.
4. In the rollout for the H&F modifier, go to "Tools" -> "Presets" -> "Load".
5. A dialogue box opens that shows various presets, including Blonde Hair, Tall Straw, Tall Grass, Sandy Blonde, Red Straight, etc. Choose "Tall Grass [breeze].shp"
That's pretty much it; the default setting seem to work pretty good, although adjusting the cut length may give you more desirable results.
Some values you may want to change are:
Random Scale: Gives random lengths to the blades of grass.
Root Thickness: Adjusts the thickness of the grass at the base (you may want to lower this a bit)
Tip thickness: Same as above, but for the end tip of the blades.
Cut length: Adjusts the overall length of the grass. (I'm not sure what the difference between Cut Length and Scale is)
One thing to mention: You may want to reduce the density (count) of the grass while making adjustments because it's easier to see the effects of changing various values. When you've reached the appropriate look, change the density back to make it thick again.
This technique creates very realistic grass without a lot of work and renders much faster than geometry-based techniques.
See the attached image for a screenshot of the render using only default settings.