Substance Painter to 3ds max VRAY - reflectivity tuning

Valentris

Greetings!

I have a question regarding to reflectivity tuning for Substance Painter -> VRAY (3dsmax) workflow:

I exported maps with VRAY preset and configured VRAYmtl according to SP guidelines (https://docs.substance3d.com/integrations/vray-for-3ds-max-157352261.html), yet there is seems to be some issue with reflectivity: quite rough dielectric part reflect way more environment color (little white\blue-ish spots on the right example picture) than it should. Just to be sure I checked export result for KeyShot - no such problem appear.
Which part of material\renderer tweaking am I missing on?
Thanks!

Eric Chadwick

Same lighting environment for all three? 

Valentris

Similar, at least. With the exact same one result would be:

So the reflectivity problem still there, especially noticeable on a line between outside and inside parts of the bag, which is "rough" on both SP and KS, but not  on 3ds max one.

Blaizer

Did you lock Fresnel IOR to Refraction IOR?

Valentris

I hadn't change default VRAYmtl parameters in IOR part, just added SP-generated map into Fresnel ior channel:

Please let me know if something else needs to be tweaked.

I'm also noticed that with a default 30,0 value of Bump channel and no additional bump (where I usually put Height map generated by SP in Vray preset) issue not really noticeable. Obviously though I still want to use 100,0 with additional bump map since without those result too flat-looking.

Eric Chadwick

IIRC, Substance uses Roughness. But V-Ray uses Glossiness, which is inverted from Roughness.

Valentris

Still, SP creates glossiness map (which matches inverted roughness) for Vray texture export preset.

Eric Chadwick

Ah ok. I bet it's your IOR map. This is a float value in V-Ray, so an 8bit bitmap will only apply 0-1 IOR. Did you export a 16bit file? 

Eric Chadwick

Oh wait. Your Reflect map is mostly white, and your Gloss is pretty bright too. Mask the Reflect to only apply to the metals, and it should work better. 

Valentris

>I bet it's your IOR map. This is a float value in V-Ray, so an 8bit bitmap will only apply 0-1 IOR. Did you export a 16bit file?

Tried, doesn't seems to make noticeable changes (unless there are some additional switches in 3ds max map settings that also should be tweaked to make in work). Though I also suspect IOR map to be the source of a problem, since KeyShot preset, which mostly has same maps (same mostly-white reflective map and inverted glossmap for Roughness), has Metallic map instead of ior.

>Mask the Reflect to only apply to the metals, and it should work better.

Yeah, guess I'll gonna do it this way. Maybe not by totally blacking-out parts of a map for non-metals (which kills all of the gloss), but manually editing Reflection map, combining with others (like on the right picture, where I multiplied it with contrasted Glossness map). Doesn't seem like really solid approach though.

Eric Chadwick

What kinds of surfaces are those based on? Rope and rough leather (I'm assuming) have very little specularity, so the diffuse lighting should do majority of the lift. Reflect would be almost nil. 

Valentris

I wanted to imitate these kind of materials for different parts of a bag:

Eric Chadwick

The outside leather should be more glossy, look at the wrinkly strip next to the zipper. 

Valentris

Yeah, I think output/color map curve tweaking does the job: