VRay Dirt: Inner Occlusion showing up on inside edges (like Ambient Occlusion)

[jacob_cementina]

Hello,

I'm working on a material that needs to have one color on inside edges and a different color on outside edges. I've been using two vray dirt nodes- one set to Ambient Occlusion for the inner edges, and one set to Inner Occlusion for the outer edges. I've used it on multiple models and it was working fine until I got to this particular model, which is showing the Ambient Occlusion color on two (but only two) of the inside edges.

I have the feeling the problem has to do with this particular model but I have no idea where it's coming from. I've found that the issue goes away when I round out the geometry on that inside edge, but this alters the model too much to be an acceptable solution.

Any ideas on how I can fix this?

-Jacob

Attachments:

1. The model in question
2. Material applied to test geometry
3. Material setup

[fixeighted]

Hard to say...you can post that model piece to investigate or probably just simpler to rebuild it.
Otherwise, try adding a smooth modifier to see if that fixes it...just add it without actually changing its settings.

[^Lele^]

It smells like a geometric issue (double faces the most likely): as mentioned, either post the model or rebuild it.

[jacob_cementina]

Hi,

Thanks for your replies. It appears that the scene file is too large to attach and this interface won't let me attach any other exported format. But you're right, the model is simple enough I can just rebuild it myself. I was just hoping to salvage this one just to know what was wrong with it, as I'm kind of expecting it to happen again in the future.

Thanks anyway,
Jacob

[fixeighted]

Don't attach the entire scene, just that particular object
If it is a .max file then zip it, or dropbox a link to it directly.

[jacob_cementina]

Aha! When I said "scene" I did just mean the object, but either way, it's the zipping part that I missed. Hopefully this works. Thanks for following up!

[^Lele^]

There seems to be at least one issue with vrayDirt: the distribution parameter is taken into account with the inner occlusion mode, even though the control is greyed out.
Further, the model seems right by the metrics i checked (faces, normals, water-tightness, and so on.), so there could be another bug at play.
I'll report back here as my findings get verified (or not) and we'll file the potential bugs.

[jacob_cementina]

Okay, great. Thanks Lele.

[Margarita.Stoeva]

Hello jacob_cementina

Thanks for providing your scene! I checked on it and the polygons on the bottom part are closer than 0.8" (the radius set for blue inner occlusion dirt) to the edges that have mixed dirt shading.
So, the result you see is actually expected because by design VRayDirt traces the geometry below surface with the Inner occlusion mode as described in our documentation.

A simple workaround would be to select the polygons with mtlID 2 (they are the bottom part of your geometry) and detach them to separate object.
You already have the "Consider same object only" option enabled in the blue VRayDirt shading so it works straight away.
Note, that making this suggestion, I guess you don't need the geometry as a whole object - there are currently some open edges in it so I don't expect this approach to cause any disturbances. Feel free to share if this worked or there is something else to consider in your scene.

Best regards,
Margarita

[jacob_cementina]

Hi Margarita.Stoeva

Yep, that worked! Thank you so much for taking the time to check it out. And you're right, the bottom of the model doesn't show up in renderings so I just deleted that whole section of geometry. And yesterday I found another model with the same issue and knew immediately how to fix it, so you've already saved me from ongoing frustration on this project.

Thank you again for your help!

-Jacob

[Margarita.Stoeva]

Great to hear this! I'm glad I could help.
Deleting the bottom part may not be wise when it must be seen in reflections and shadows, so keep in mind the detach approach too.

[Margarita.Stoeva]

Good news!
The incorrect graying out of Distribution parameter while VRayDirt is in Inner occlusion mode is now fixed in our freshly released V-Ray 6 Hotfix 1 today.

There seems to be at least one issue with vrayDirt: the distribution parameter is taken into account with the inner occlusion mode, even though the control is greyed out.
....

The Distribution parameter is properly used and active with modes Inner occlusion, Ambient occlusion and Ambient + inner occlusion.
It's grayed out for the reflection occlusion modes because the Reflection glossiness parameter is used there instead.