Vray Light Noise Problem

[jervistuazon]

Hi guys, I've got a problem with noisy lighting. I have this scene where the sunlight passes though a trellis to create shadow effect, but it's a bit dark so I tried adding a standard vray light plane behind the scene, turning off the affect reflection and specular, behind the trellis. It brighten up the scene but now the part where the vray light hits, its very noisy. Any suggestions how to approach or fix this problem?

 

I've, included an image pass of vray light select, where you could see the noise is very apparent.

[Francisco Penaloza]

Check all your materials and textures are with the correct gamma, then adjust your exposure as need it, with such Sunlight I don't see the need to extra lighting.

In any case always when there is that noise it means no enough samples, you need more samples or lower your noise threshold.

[jervistuazon]

Thanks for the feedback, Im not really sure how the textures gamma would affect the lighting, but Ill give it a try. I put another light behind cause its dark behind the trellis,This is the 2nd time Ive encountered this kind of problem with similar scene using vray light plane to add additional lighting behind a screen/trellis. Im using progressive with universal settings min 1/ max 100 and 0 noise threshold, the noise is just horrible with the vray light plane, but without it the white surface and every surface affected by vray light is very smooth.

[Francisco Penaloza]

The gamma does affect textures, and even bouncing light. If there is the wrong gamma your texture may not bounce enough light, the same thing happens if you use 100% back colors in your shader, you should never use 100% black or 100% white. besides most of the material should have some sort of reflection. Some very glossy others sharper this also help to the light bouncing.

 

If your light plane is too large it will take more samples to clean.

If you are using progressive mode you should not set your Noise threshold to 0, use another number such 0.002 or so but even that is very high. There should be a relation between the Max number of samples and the noise threshold. Use the Sample rate pass to see if you are using all your samples or you need more.

You mentioned that you are using progressive mode, are you letting render the image long enough?? or it is also 1-minute default?

[jervistuazon]

Yes almost all materials do exhibit reflection/glossiness to some extents but anyways, my main problem is vray light plane causing too much noise. Yes, I do leave it to render for a long time, my time limit is set to 0, without vray light plane in just 10 seconds I have a very clean render on that part, but with the vray light, even though im waiting for 5-10 minutes it is still noisy, so I guess the problem is the vray light, im thinking maybe because of the shadow, it need to pass though many perforation thats why vray is having a hard time to clean up the shadow?

[Francisco Penaloza]

well hard to tell without seeing more of your scene or your setting, but using the sample rate pass you can debug that problem.

 

If you can, you can send me part of the scene, just a few element that can replicate that effect so I can take a look.

Edited July 8, 2017 by fco3d

[Chris MacDonald]

This is because of VRay's adaptive sampling. That light doesn't contribute enough to the scene to warrant more sampling of it - that's why it's noisy. You can override this a couple of ways.

 

You can either increase the "Minimum shading rate", which will globally make VRay sample more on things like glossy reflections, GI, shadows etc. Pro's are that it will improve overall image quality, cons are that it will take longer to render and given the small contribution from that light, might not make that large a difference.

 

You could check the "Use local subdivs" and increase the offending light's subdivisions setting. Pro's are that it's a targeted approach so won't significantly impact render times. Cons are that if there are materials in your scene with high subdivs (think imported assets, etc) then these could take a long time to render - though you could rectify this easily with a script. This would be my preferred method.

 

You could change the "adaptive amount" to 0 and drop the DMC noise threshold to the lowest value possible. This isn't guaranteed to work and should be a last option really.

 

There are probably a couple of other ways that aren't coming to my mind right now, but those two are the most obvious. Changing the min/max AA settings likely won't help with this.

[Chris MacDonald]

Any luck?

[Francisco Penaloza]

Any luck?

 

No man it been a very unlucky week for me

[garretthoyos]

I had this issue when using v-ray in max where my light selects were crazy noisy. It turned out to be a multi-sub object material had somehow created a standard material, and even though it was only applied to a single object that wasn't even seen in the render, just by it's presence it was causing this noise - so for anyone who has this noisy render in v-ray in the elements - convert all materials to v-ray materials (one button tool in max customize vray options). Or just find the standard materials and remove them from the scene. It immediately solved my issue.