Vray 1.5 / Grass Displacement / Moire Pattern Problem

[samuel_bubat]

Hallo,

I have a problem making displaced Grass with 1.5 like i could do it with 1.4703.

Made with 1.4703
This is how it should look like.


This is how it comes out from 1.5
Disregard the leaf Size.. but notice the square pattern in the picture.


better noticable in this picture.


I used a "splat" map but also tested with "cellular".
The underlying box is not tessalated. Just one face per side.
What I tried so far.
All different AA Methods.
"View Dependant" Displ. on/off
Filter Texmap on/off.
I made shure I have a clean scene without any remains from 1.4.
Vray Default Displacement Parameters in the global Render Menue on/off.
Different Bucket Size.
Rendered local and through the Network.
So far I always get the same moire Pattern.

What can I do to solve this problem. I´m using displaced grass like this
in a lot of projects !

Thank You,

sam

[Morbid Angel]

this is a known issue, which is present not only in vray, but in mr aswell. When the edge length becomes too low, this checker pattern appears. Unfortinantly there is no way to solve this when using 3d displacement. For grass you may use 2d displacement instead which is a different method all together.
Eather that, or you may lower the edge length to an extremly low value, something like 0.01 then the checker will dissapear becuase the faces will become miniscule, but the render time will fly up.

[samuel_bubat]

I know what you mean.. I experienced similar things.. in the past as well. But this must be some other problem !!. If you look at the the second picture I posted (1.5) you´ll see that the displacement (The Grass leaves) is actually quite large. You can clearly see the triangles. But still it has this strange pattern. And.. it always worked well in 1.4073. So Please don´t tell
me that I have to live with that !!!

[Morbid Angel]

i think its very appealing

[vlado]

From what I can see, in the 1.47.03 render, the individual sub-triangles are smaller, which is why this issue is less noticeable there (but it still can happen - there were post here for this). The way to deal with this is to reduce the Edge length or use 2d displacement.

Best regards,
Vlado

[Morbid Angel]

vlado is such thing possible in render man displacements? since its a totally different engine does it suffer same deed?

[vlado]

vlado is such thing possible in render man displacements? since its a totally different engine does it suffer same deed?

You are likely to run into similar issues, yes. I have some demo version of 3delight here, let me do a quick test...

Best regards,
Vlado