How to set up displacement to match the result in Mudbox?

[jasonhuang1115]

Hi,

I created an rudimentary scene to test displacement rendering workflow.
The displacement seems to get clipped when rendered in VRay for Maya as show in the attached image. The mudbox viewport screen cap is also attached for comparison. (Maya 2011 Hotfix3, VRay for Maya 2.02 Beta)

I extracted the displacement map as 32-bit EXR out of Mudbox 2011 and simply plug the map in the VRaymtl's shading group node.

displacement map and Maya scene file. http://www.yousendit.com/download/Vn...Tk1lcEpFQlE9PQ

[jasonhuang1115]

I re-extracted the displacement map from Mudbox and render with mental ray for comparison. (left: VRay, right: mental ray)

A lambert is assigned with the displacement map plugged to its shading group node. For the test with mental ray, A subD approx. node is plugged to the cube for mental ray rendering.
For the test with VRay, I assign Displacement control with default setting. Should I trial-and-error the displacement amount to eyeball the displacement until it looks closer to what I sculpt in Mudbox? That's not the workflow I expect.

PS. Does this issue have to do the model's size? The cube is scale up 400 times as I am working in centimeters as the default measurement scale in Maya?

[ChewyPixels]

Jason, I was having the same problem trying to get the same displacement quality that I would get with mental ray. Could never find the solution at the time so I just gave up. This was a while ago using v1.5. I haven't run any tests with v2 yet.

@vlado - What is the proper workflow for getting an exact representation of a sculpted model using vray's displacement? Back when I was doing my own tests with vray displacement, it seems that I tried every known "solution" with no luck. I probably shouldn't be asking just yet since I haven't done any recent test using the latest v2 build.

[GatesB]

I know there was someone a while back who got a 1:1 workflow from MudBox -> Vray using vector displacement. You had to convert the values in the map to put them in the required ranges that Vray expects using the hypergraph, they posted an example and explained the process as well, just do a search for mudbox vector displacement. Whether that applies to "traditional" displacement as well, I dunno.

[jasonhuang1115]

I know there was someone a while back who got a 1:1 workflow from MudBox -> Vray using vector displacement. You had to convert the values in the map to put them in the required ranges that Vray expects using the hypergraph, they posted an example and explained the process as well, just do a search for mudbox vector displacement. Whether that applies to "traditional" displacement as well, I dunno.

I guess you are referring to this thread: http://www.chaosgroup.com/forums/vbu...r+displacement

Jason, I was having the same problem trying to get the same displacement quality that I would get with mental ray. Could never find the solution at the time so I just gave up. This was a while ago using v1.5. I haven't run any tests with v2 yet.

@vlado - What is the proper workflow for getting an exact representation of a sculpted model using vray's displacement? Back when I was doing my own tests with vray displacement, it seems that I tried every known "solution" with no luck. I probably shouldn't be asking just yet since I haven't done any recent test using the latest v2 build.

After some more tests, I was able to better match the result in Mudbox. What I learn is that the scale of the model does matter. That means one has to be careful how he transfer meshes between Maya and Mudbox. There can be several ways depending on which version of Maya and Mudbox you are using. Are you using the ADSK's one-click transfer feature, or OBJ, or FBX? In my tests, different approaches yield different result and varying displacement amount.
So far, I got the best result by transferring meshes using old-school OBJ and extracted both displacement and normal maps from Mudbox. This way I don't have to eyeball the displacement amount or other settings in the VRay Displacement Control.