With the current update for 3ds Max 2021 importing FBX file will assign a PhysicalMaterial instead of Standard mtl which was the the old behavior .
The problem with that is VRay converter doesn’t currently convert these materials to Vraymtl which I need because :
1-They are not comptable with Vray gpu
2- Slow to render with VRay CPU
3- When possible, I prefer to stay away from anything related to Autodesk when it comes to shading and rendering.
Lele did wrote a script to do the opposite (Thank you! ) Here but I think an official converter would be necessary with the current situation.
I haven’t seen the slowdown with CPU, do you have a scene to share?
It’s internally translated to a V-Ray material, so if it’s slower it’s likely a bug.
but it can easily replicated with a teapot
default physical material vs default VRay material ( increase reflection to full in order to match) and the render went from 17 sec to 1 m 34 sec and with weird artifices
attached a simple scene for that .
I have a scene that show a very different result comparing to VRaymtl with artifices and the render time going up. it is for a client so I will zip it and send it to your email ( Max 2018 if that’s okay)
I cannot get to the attachment, somehow.
Could you kindly mail it to me?
EDIT:while waiting, i tested again, and the most i see is a 10% speed difference, under controlled conditions.
The physical material doesn’t have glossy fresnel, f.e., which is enabled by default in the V-RayMtl, and there are a slew of little differences (read: the physical material is less featured) which could contribute to the rendertime differences you are experiencing.
That’s strange as I can’t download the attachment either .
Here is the Max file
I usually take the imported materials just as as starting point ( Mainly the textures and colors ) and refine it later for better look so a simple conversion would be enough for me even if it doesn’t match 1 to 1 at the moment.
Yeah, it’s down to number of reflective bounces, and glossy fresnel.
You’ll notice the physmat “hangs” where the teapot edges inter-reflect.
The VRayMtl, between a set bounce level of 5, and glossy fresnel which may contribute to dimming (your setup has perfect white, perfectly sharp reflections, that doesn’t help with extinction under sunlight), and hence speed up.
Deactivate glossy fresnel, set the global bounces to, say 5, and render again: you’ll see the difference is all but gone.
EDIT: because the teapot isn’t shelled, also turn on “reflect on back side” for the vrayMtl. Minor, but contributing.
This should show you why conversion is always going to be troublesome, be it internally done like it is now, or through scripting. When feature sets do not match, and some things are local, while others global, and other still are hardcoded, it becomes an insoluble problem. Looks, when not rendertimes, will always end up differring, sometimes by a lot (think of the development the VRayMtl has gone through, in the time the max Physmat has stood still.)
Thank you ! I remember switching off glossy frensal in my tests but beside the look I couldn’t see any difference in render time.
.Anyway I will test what you have mentioned with the other scene ( which have a bit more complicated shader) to see if that will help .
But still the main issue is that, I don’t want to build my scene using other materials than the built in if possible.. you start with removing glossy drensal and 10% speed then reducing the bounces then you find another little feature/setup that doesn’t work as intended and you find yourself trying to fight with the settings and changing the whole workflow to get what you want while you could just use the Vraymtl and do the job properly .
it is great that VRay support this shader but if it will bring trouble to use I would prefer to avoid it .
I hope you see my point with this and thanks again for checking the file! .
@M.Max How do you manage to get those physical materials to be created on import?
What’s the source application?
I ask, as if i make a scene with a vraymtl and export it, on import the material is kept.
Sorry, I should have mentioned that I built this material in 3DS max for debug purpose .
and yes exporting and importing will respect the materials as long as you are doing all that in Max .
in my case ,I’m receiving files from Sketchup and Blender ( fbx) and the imported materials would be the Physical Material by default .