Answered: DDO and Softimage/Arnold, reflection issue.....

RobWu

Hi all,

First post after some lurking ;-)
I hope there are some DDO & Softimage 2014SP2 / Arnold users here to help with some quick questions.

I start my projects in DDO with the 'Arnold linear' settings, and when I'm done I export the images in 'Arnold linear' as well.
In Softimage, I have Arnold set to gamma 1,1,1 and have turned on my color management for render regions to compensate. All images are set to 'Automatic' in the texture node.
For quicker renders, I convert my exported textures into .tx files (just a simple maketx conversion)

All the textures are working as expected after plugged in into a 'Standard' shader, but I do have some big differences in the reflection parts of a Arnold render, compared to 3DO. In SI/Arnold the reflections are much stronger compared to the 3DO window.
It looks like there's a (gamma?) treatment on the roughness and IOR texture, but have no real solution yet where to solve this.

I hope that someone can help out here, as it seems some small setting somewhere.
The strange thing is that in Maya it works as expected. Despite the s****y color correction in Maya 2016 ;-)

Thanks for any tips!

rob

Billy Lundevall

Hello! I actually made the setup for the Arnold exporter along with one of my friends, a college and with collaboration from the SolidAngle team. 

In Maya all grayscale maps are expected to be set to "Alpha Is Luminance" under color balance. This would be roughness and reflectance at normal, NOT specular. I don't use Softimage and don't know what the equivalent setting would be.

The roughness setting should be set to GGX and not Beckman.

Arnold also doesn't expect the roughness map or the normal map to be linear, something that just takes care of itself in Maya but I don't know about Softimage.

Hope it helps .

Regards, Billy.

RobWu

Hi Billy,

Thanks for the reply

Yes, it seems to have something to do with the differences between Arnold in SI and Maya, regarding the roughness and fresnel texture treatment. In Maya you indeed compensate with the 'Alpha is Luminance' option for these two textures.

Second: It seems the SI and Maya 'Standard' have different 'Microfacet Distribution' settings; Beckman for SI and GGX for Maya. At least in my versions of Arnold.
Switching this in SI to GGX already improved the image a lot, matching it more to the 3DO version.

Third: Comparing all three, you still can see differences between Maya and SI, although all render settings and HDRI are the same. The Maya version is still more glossy, compared to the 3DO and SI renders.



Hope this makes sense, just trying to get as close as possible to the 3DO version. 

cheers!

rob

Billy Lundevall

Have you also put your roughness map into specular roughness? I usually get closer results that way.

Regardless, this should be looked into further as there shouldn't be a difference at the end. Perhaps we could check it out some day in the Quixel hangout?

RobWu

Hi Billy,

Just to rule everything out, I created completely new scene set-ups in Maya and SI.
So to see if there were no errors in color correction management and such somehow. I also exported new textures from Quixel again, and created new .tx files.

The scenes were set up the exact same way as before, but now I'm getting the same results between applications. I don't know if there was some anomaly in the textures, or that some gamma setting was ignored in the render. I have a feeling in Maya gamma was rendered double in the old scene, despite the proper color correction/gamma settings.

Sorry for the noise, but with GGX my SI renders look awesome too now!

cheers!

rob

Billy Lundevall

Alright, glad I could help .