Vray Light MTL subdivs.

[Vizioen]

Subdivs – Controls the number of samples used for direct sampling of the mesh light. Lower values may be faster to calculate, but may introduce noise in the image. Higher values reduce the noise, but increase render times. Note that this parameter is available for changing only when Use local subdivs is enabled in the Global DMC Settings. This parameter is not available when the renderer is set to GPU.

This is what the manual says, shouldn't the parameter be grayed out if Use Local subdivs isn't enabled? Because now I can "change" it, even if it's disabled, this might confuse some people.

[Philip Shounev]

Thank you for your feedback. It's already been logged in our bug tracker under VMAX-3553. I'll additionally bump it up.

Best regards,
Philip

[TerriBrown3D]

Hi guys.

I'm having problems with the VrayLightMtl. I'm finding that when I try use it as a light source (as stated here https://docs.chaosgroup.com/display/VMAX/VRayLightMtl), the result is always very grainy compared to a normal Vray Light. Firstly, I don't have the option Ashley is refering to in my Global DMC Settings, and I have no subdivisions slider in my VrayLightMtl settings (things have obviously been adjusted in the latest build of Vray). So how come it's rendering so much grainier than a normal light?

I am using Vray 5, hotfix 2, and 3DS Max 2021.

Please help, as it's really quick to use the VrayLightMtl instead of setting up normal lights to illuminate a large apartment building...which I am busy trying to do!

Thanks,
Terri

[Vizioen]

Hi Terri, VrayLightMTL isn't really optimal to light scenes with. You need to use it in conjuction with a regular light (plane, disc, sphere,...) If you use it solely to light an apartment, you will get grainy results.

edit: I am now reading the sidenotes and didn't know this myself, as I almost always use VrayLightMTL in conjunction with a Multi-sub. Is this something that still applies?

• The direct illumination options will only work properly if VRayLightMtl is the only material applied to the object. It will not work if the material is part of a complex material like Multi/sub-object or VRayBlendMtl. This restriction will probably be removed in a future release.

[TerriBrown3D]

Yeah I also learnt that little subnote today...it's a pity because you can easily vary light intensity with a MultiSub-object Mtl.

I have never used the VrayLightMtl to solely illuminate buildings...although it would be awesome if that were one day possible. However, even when I have say, 10 Vray Lights and only one object using the VrayLightMtl, that one object still makes things grainy.

It's far from ideal.

[^Lele^]

There are two workarounds to the limitations you're facing with the multi-sub material.
They're both enabled by selecting the right IDs and detaching the faces to pull them out as individual geo.

You'll be able to use the lightMtl as direct lighter then, or use those faces as a mesh light (one of the modes of standard lights).

Both methods will be quick and cleaner than trying to light the scene with GI only.