Grass in Animations

[Macer]

I know that this has been asked dozens of times (I've read all the posts!) but I still can't find a solution to my problem. So after days of trawling through web pages I thought I'd start a new thread.

 

I tried hard to create a reasonable looking grass from maps only but couldn't get anything that looked half decent. I then moved on to displacement and it worked a treat. I was really happy with the results, it looked realistic up close and from a distance. I can rendering frames for an animation (1280x720) in approx 15-20mins, which I thought was quite good. But the grass moves/flickers/crawls and it looks really bad in the animation.

 

I tried changing the displacement map from cellular to a self created jpeg in the hope that it would create the blades of grass in the same spot on the terrain, on each frame. I've tried several other things but no luck at all. Are there any other techniques for getting the displacement effect to occur at the same location on each frame?

 

The area of grass is really large (think school grounds) and I'm limited to VIZ and MR3.5.

 

Any other sugguestions, tips, methods for creating grass on this scale, within my constraints would really be appreciated.....

 

Thanks in advanced (and for all the info I've already recieved from this site in general!)

[gfa2]

I then moved on to displacement.....the grass moves/flickers/crawls and it looks really bad in the animation.

 

I'm getting the same thing in Vray even with precalculated IR map and some pretty high settings. Motion blur helps a little bit but I'm still not totally satisfied with the results. I too would like to hear other thoughts on this subject.

[thatch]

I then moved on to displacement.....the grass moves/flickers/crawls and it looks really bad in the animation.

 

This may be your antialiasing settings causing the moves/flickers/crawls, try using a filter/setting appropriate for animation (video filter in vray) or even try changing your map filtering to summed area.

[Macer]

Thanks for your reply Thatch.

 

I upped my antialiasing settings and changed my map filtering to summed area. The image looks sharper but still not helping the animation problem.

 

The blades of grass are well behaved when the camera doesn't move (ie: each blade is created in the same spot each frame). But when the camera is animated the blades appear in different positions every frame. Its almost as though the renderer positions the material maps differently for each frame. If this is the case then will displacement work at all with animations or should it be reserved for stills only? I've probably just got one checkbox somewhere unchecked causing this problem..... ...who knows???

 

I've attached two test images to demonstrate the problem (this isn't the grass used in the full animation but it will do for this purpose). Note the blades of grass in front of the teapot, see how they are in a completely different postition in the second frame, even when accounting for the minimal camera movement. It might not look much on these two images but it makes you feel sea sick in high definition. Sorry about the small size here!

 

Can anyone offer any ideas on this??

 

Thanks again for any help!

[mnemeth]

Has anyone mentioned enabling local supersampling in the material parameters? This helps eliminate a similar problem on a noise mapped road when rendering vehicle animations.