Zbrush to maya displacement scale issue

[hug03018446]

Hi everyone. I wonder if anyone can shed some light on an issue I’m having regarding the displacement scale from Zbrush to Maya/Arnold.

The issue is, that the displacement map when applied to a mesh in Maya does not look the same as the mesh looks in Zbrush. The difference is the depth of the displacement is much smaller in maya. The issue is not to do with the scalar zero value being different in arnold (set to 0.5 in both ) and nor is it an issue with the color space of the image file (raw - and no .tx files generated from arnold that might screw things up).

Let me just explain a little about the steps I’m taking to generate and apply the displacement. I have a mesh that has been exported from maya in the default scale (1 unit = 1 cm) making sure that the object exported doesn’t have any scaling and the pivots are reset to the origin
I then bring this into zbrush and immediately scale the geometry in the geometry tab to 0.92817 (so 92cm), store a morph target before subdividing to level 4, I then go ahead and mask and move a section of the mesh outwards so that there is something to bake down in displacement
Next I bake the displacement by going down to the lowest subdivision level>switch the morph target and then bake with settings appropriate for arnold/maya. Back in maya, I apply the displacement image with these settings and with the arnold displacement setting set to 1 I expected a result that matched what was in zbrush. However the result was a lot more subtle and I had to crank the displacement amount to 4 or 5 before it started to get close to where it needed to be.

So the question is why? Why does a value of 1 not reflect what I’m seeing in zbrush, and if there is another value around the 4 or 5 mark then what is it exactly? It doesn’t make much sense to eyeball it.

Any help will be very much appreciated.

[Spyndel]

Hello @hug03018446

Every program manages things differently, especially with regard to displacement. These frankly sound like questions better directed at other Maya/Arnold users, as it has to do with the way that program works.

[hug03018446]

Hi @Spyndel. Thanks for your reply. I will post this question on an arnold forum to see what they say.

Thanks very much

[hug03018446]

A little update on this issue, I have been talking to a very helpful person over on the technical support for Arnold and he has taken my sample file and confirmed that everything in arnold is setup correct and the result is what he would expect from examining the displacement map. He told me that the maximum value in the displacement map is about 1.9 and that is how many units the polygons were displaced.

So there seems to be something in Zbrush that I am missing, I thought it would have been the scale within Zbrush but playing with different scales gave me a consistent incorrect result in arnold. Does anyone have any suggestion as to what the problem might be?

Thanks