Vray Fur produces strange patches

[Alex_M]

I'm getting some weird results when rendering vray fur. In this case I'm using it to create grass. You can see the strange patches Vray Fur produces. What are these? Any way to avoid it?

[super gnu]

dunno what the patches are, but did you finely subdivide base mesh? if those are showing original mesh triangles, you will probably get a big speed boost from subdiving mesh, and it may fix/ hide your problem too. fur likes a fine base mesh.

[Alex_M]

Thanks, the large polygons was indeed the problem. However, now the patches are just smaller and as obvious as before. I see this peculiarity is also highlighted in the help documents, I should have checked them first (I feel stupid now). But again, how fine should the mesh be? It's already pretty fine and I still see small patches.



By the way, I think the help for Vray Fur is not up to date. The curl parameter is missing. Not a big deal of course, just saying.

EDIT: I just subdivided the mesh even more (5 turbosmooth subdivs) and now the problem is not visible. The mesh is now insanely dense but at least the problem is gone. Is this the correct way to do it?

[super gnu]

no, the issue is something else, you should not need to subdivide to hide errors.

subdivisions just used to speed up the rendering, but mesh density shouldnt need to ve very high, i usually subdivide down to 10-40 cm , depending on scene scale.

[Alex_M]

Hmm.. The subdivision on the last image I posted is 8.5 cm per polygon. It goes away when the polygons are 2 cm in length.

[Morbid Angel]

how are you masking out the grass from those rocks - dist tex? maybe its related, I've never seen this before. Grass looks nice btw.

[Alex_M]

Thanks, Dmitry. Your guess is correct, it's VrayDistanceTex. It can create a number of cool effects like this one. Just put it in the density map slot of vray fur and you're good to go.
Below is my best attempt with really high subdivision (2cm polygons).



Looks great now but again, I had to make the mesh very dense to avoid the patches. I don't know if it's normal so if somebody from Chaos could confirm that would be great. Maybe it's something that I'm not doing right.

[Morbid Angel]

so does the grass look wrong, if you don't use any density texture (i.e remove your distance tex)

[Alex_M]

It looks the same with or without it.

[svetlozar.draganov]

Would it be possible to attach that scene(or a simplified version of it) for investigation?

[Alex_M]

Sure, please see attached.

[Zdravko.Keremidchiev]

There is an issue with the new Curl options. I made a note about that, we are looking into it.

[Alex_M]

Thanks for the tip, Zdravko. I'll keep this in mind.

[Zdravko.Keremidchiev]

This issue has been fixed for the next SP.

[Alex_M]

Awesome! Can't wait to download and test it.