View Full Version : Field of rolling grass (animation)

03 March 2007, 07:16 PM
I'm trying to animate a field of tall grass waving in a light breeze. The goal is to get this looking as good as possible, while retaining the ability to move characters through the grass (displacing the grass realistically). Since this is a relatively slow low-flyby shot, detail is important but it doesn't have to be too detailed. They overall portrayal of the scene is most important, but all the parts must fit together naturally.

So far I have attempted this using fur on a NURBS plane, set up to look like a dry grass, and animated using a hair system which is affected by the internal turbulence controls in Maya Hair. The stiffness is also turned way up since this is grass, not hair, and should stand up straight unless affected by the wind.

I have experimented with different settings for turbulence, hair count and placement randomness, height, and the number of hairs affecting each fur (currently set to 2). I have yet been unable to achieve a satisfactory result. Any ideas on how I should go about doing this - particularly displacement of grass in response to characters moving through it?

Thanks in advance.

03 March 2007, 08:10 PM
I think your definately on the right track using the hair system to drive your motion of grass, Fur however wouldnt be my first choice id use Paint effects then convert it to polys before rendering. The hair system should respond to a localized field applied to your character or object, but i also think it can be made to collide with geometry, so you may consider using a low proxy version of your character as your collision surface...depending on the detail of your shot this approach will become very heavy very fast but if you manage your display layers properly and maintain a clean scene hierarchy you should be able to simulate with relative ease...that being said i hope you have a powerful machine hehe....good luck

03 March 2007, 10:43 PM
Thanks for the advice, mandark - I'll let you know how it goes. Is there any particular reason you'd choose PaintFX over Fur? Also, I had tried to avoid excessive computation by reducing the number of hairs to something very small (5 by 5 or so). It look's like I'll definitely have to up that, especially if I plan on using the system to interact with the characters.

03 March 2007, 10:52 PM
The big reason why i like using paint effects is it has an interactive feedback...meaning you can see in the viewport through a simple playblast what the final result will look like, that and you have way more control over the shape or characteristics of your "grass" and now can convert to mesh to gain the advantages of any renderer. Fur gives you a representation that looks nothing like your final rendered image and i believe it is still a post process so it has the limitations that you cant use black hole shaders on it etc.

Its been awhile since ive used if im wrong here someone can tell me...but i have succesfully made alot of grass type scenes using the technique i outlined above.

Most important thing is to have a clean scene hierarchy (meaning no unnecessary nodes or objects, clean DAG objects and a good grouping structure) so you can manage large amounts of info easily and a good range of display layers so you can simulate on problem areas without having to wait for a heavy scene to calculate.

05 May 2007, 08:05 PM
I 2nd going the PaintFX route...

You get turbulence settings allready attached (for your wind), and you can use PaintFX->create modifier to create a simplistic object to deform your grass/plants with (by attaching a couple of those modifiers to the feet of your character).

CGTalk Moderation
05 May 2007, 08:05 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.