Unwanted grain and noise in renderings

[dpwr]

I'm getting noise in odd places on renderings using v-ray. I suspect this is a lighting issue. My lights and materials are v-ray. I am rendering with environment fog (emission multiplier 1, distance 10,000, height 300, scatter GI w/12 bounces). Only a few IES lights are set to affect environment fog, the lights are off. The same noise results when environment fog is turned off. The wood wall is a generic v-ray material, with a jpg image map. The back of the chairs are also grainy, also a generic material with a simple color assigned.

I'm on a Mac, running 9.2.4 and v-ray 5. The image rendered for 30 minutes. Any ideas where to start looking?

[Justin Montoya]

Hi DPR,

I'd have to see your VRay settings to know for sure, but first thought would be to make sure you are using the brilliant VRay denoiser?  Even on mild setting, it can really speed these up.

Also, sometimes I've found imported complex geometry like the 3D people to really mess up rendering times.  Make sure these are as simple mesh as possible (Reduce Mesh), and if that doesn't work, you can always turn them into VRSCENE files for placing like a proxy and they won't slow you down so much.  You can check this if you turn off the 3D people and render and it goes much faster...

Edited August 4, 2023 by Justin Montoya

[dpwr]

Thanks, Justin. Where is the brilliant VRay denoiser? I have it selected in the VRay settings palette, and "mild" in the pull down.

I can try without the people models. I do need to improve render speeds as well. 30 minutes per image is rough.

[Justin Montoya]

How large is your output image?  1920x1080?  Bigger?  The bigger, the longer the rendering, which on CPU on a Mac may be your limiting factor in this version of VRay.  That could be improved in an upcoming release, TBD.

What are your camera settings?  Default?

Try changing the Denoiser Preset to Default and slide the Update Effects over to Very Often.  

Then under Quality you can set a time limit and noise limit.  I would expect less than 2 minutes for a rendering of this here unless it's a huge output image.

You can also adjust the Optimizations like Max. Trace Depth, which should be no more than 5 or 6 here.

[dpwr]

Thank you, Justin.

Image size is 2400x1350 (16:9). Default camera settings. I've tried the adjustments you suggested and a lot of settings this afternoon and turned lighting on/off and am still getting grain. I also changed the wood image map to a solid color and am still getting grain in the same places. When I rendered at 4-5 minutes the backs and arms of the chairs looked less smooth.

I can send you the file if you want to check any settings.

[dpwr]

Another image map test... It was the wood grain I was mapping.

[Justin Montoya]

Ah yes!  Some of those default materials have some high end settings turned on that can cause this.  Likely too much gloss.

[dpwr]

That’s likely. I also stretched the wood grain when mapping it onto the objects.

To test the orange, I just opened the wood jpg in PS and made it a solid orange. So all of the gloss settings should be the same, the only difference is the reference map.

[Justin Montoya]

Good investigation..

The problem I'm seeing is your gloss factor of 1 on the wood textures.  I know this is default, with a black color for reflection, but this is very unrealistic and should be changed.   When you changed the wood to Orange, you took away the white from the wood grain map that was causing the noise.  If you turn the gloss down to a reasonable amount like .5-.75, and change the color to a mid tone grey, you should see significant improvements.  

I also noticed your wood color maps are set at 150 dpi, which is just causing larger maps without improving the rendering quality.  The image generated will only be 72 dpi, so your maps shouldn't be over that or you are just adding size and slowness there as well.   I think I remember doing this as well to improve RenderZone renderings, but that's not needed here.  Your maps will go from 12mb to 2mb, without any loss in rendering quality.

Cheers!