Hi,
Just an annoying bug I found when using V-Ray Dirt - it appears to have a faceted effect on object that have a smooth modifier on.
Would be cool to fix.
Is there a beta nightly?
Thanks heaps. Especially if you can help me fix it. 
Can you post an image of what that looks like? I don’t think we’ve done any changes to the behavior of VRayDirt.
Best regards,
Vlado
Here is some images that illustrate the problem I am having with the beta.
The left image shows the dirt in the diffuse slot
The right image is a stand alone vray material to prove that the surface model is smooth.
I have geo with an OpenSubDiv set to render with 1 subdiv on all objects but the dirt doesn’t respect that subdivision smoothness
windows 10
3ds max 2017, 19.0
Vray Beta 3.50.01
Vray material and VrayDirt
Hi Vlado, hope you are well. Is there any more I can do to help on this issue? Is this problem happening with your version of Max 2017 and Vray beta?
Im testing it and found the same problem on 3ds max 2015 Vray 3.30.03
It seems to be very ugly when I use a value like -10 in the distribution.
Is any other Vray user getting the same issue?
I Think I found the problem.
The problem is placing a negative value in the distribution - it make the dirt appear faceted.
I was trouble shooting this issue with various versions of Vray. In Vray for maya, I noticed that the dirt cannot accept negative values in the distribution.
In Vray for 3ds max, I would place a -10 value to spread the dirt and it goes completely faceted
Therefore I wish that a fix be made to vray Dirt that allows negative values for distribution and that its smooth when doing so.
Facited effects can also be made by adding 100 to the x,y or z
So I wish for any faceting to be completely smoothed.
The V-Ray dirt can appear faceted on smooth objects. This can happen with negative values in the distribution and high values in the bias of x, y or z.
Artists wish to use V-Ray dirt with the expectation that any parameter input will yield smooth results.
I hope that this can be updated soon.
I don’t understand your reply, it’s definitely a bug!
hahaha okay I re-wrote my comment. Not even I could understand what I was saying. I made my sentences very smooth this time.
jstrob, thanks so much for your input on this post! - we figured it out!
ok now i understand!
I couldn’t replicate the faceting neither with the bias nor with the negative distribution values.
Would it be possible to attach those scenes for investigation? We won’t need complicated geometry like motorbike, cylinders are just fine.
Thank you very much in advance.
Here is a scene I made to test it. Please let me know if there are any issues with it.
https://drive.google.com/file/d/0B3HEjDe50CFzMmNtYm9Rc2JVMTg/view?usp=sharing
I hope your are testing with beta 3.55.01. That’s what we are testing.
But I am getting the same results with 3ds max 2015 using Vray 03.40.03
This is so odd. I just dont know what to do. I hope it can be fixed
Do you think it could be because I have 2 versions of 3ds max and 2 versions of Vray?
We have both the bias and the distribution issues reported and will post here on any updates.
(Increasing the subdivs of the VRayDirt seems to help a bit, although not in all case we’ve tested. Still worth a shot, though.)
Thanks Miroslav!
just to say it seems to happen here as well
increasing subds doesn’t solve it, only raising distribution helps
no negative distribution and no bias
max 2017 and 3.50.01
Hi! I work with max 2020.3 and vray 6 hotfix 2 and I still got this issue. DISTRIBUTION below 1 and BIAS are introducing faceting to the meshes. It only works good on very cubic meshes with only a few and unsmoothed polygons.
Last time I checked we have this issue on Vray for C4D too, it would be nice to have this fixed, the distribution parameter is very important.