vrayFur and vrayDirt

[lukeRFH]

I've been trying to use a vrayDirt map to drive the density of vrayFur. I was able to convert the color information into an alpha channel using layerTexture and seemed to get expected results when I was using IPR to render. But when I went to go make my final render the vrayFur seems to have ignored the dirt map.

I have attached two images of a simplified scene. One is the result using IPR and the other is the result when I go to render a final image. I have plugged the vrayDirt result into the diffuse channel of the scatter object so you can see the result I am expecting. There is a separate bitmap driving the fur thickness, hence the difference sizes.

I have tried both bucket and progressive render engines. I am using the CPU, not GPU. I am using Maya 2019.3.1 and Vray 4.30.03. Let me know if you need any other info.

Does anyone have any ideas? Is there something glaringly obvious that I'm missing? The only thing I can think of is that in IPR Vray generates the dirt before the fur and visa versa for production render.

Thanks for any help!

[hermit.crab]

Could you send the scene to support@chaosgroup.com so we can take a look? Mention this thread in the e-mail.

EDIT: From what I tested, it seems to work on IPR, indeed. However, I get no fur on production. Best to look at your scene.

[lukeRFH]

sure. I will send it right over. Thanks!

[hermit.crab]

Thanks for the provided scene. The behavior is expected (similar to using VRayDirt for displacement). To achieve the effect, you may bake the VRayDirt and use it directly as a map or use an alternative method with the VRayDistanceTex.

[Dan Andersen]

Aleksandar>> To my understanding, this is due to evaluation order? So VRayDirt evaluates after geo compile, while VRayDistanceTex evaluates before?

If this is the case, how difficult would it be to - per node (dirt, curvature, distance etc) - have an option that lets you choose if that node should evaluate before or after subdivision/displacement? I'm guessing it's difficult

[hermit.crab]

In production, yes. The reason it works in IPR is because there is a working raytracer during the hair compilation. It's a bit more complicated than it seems.

[lukeRFH]

Thanks for the response. I figured the issue was something like that. I will try an alternative. Thanks Aleksandar!