Massive Global Illumination Noise Vray & 3DS Max

[Andrew Adams]

Hi guys, I'm hoping that you can help me out. I have been trying all sorts of things to improve the lighting in my interior scene but I am getting massive (and I mean massive) noise in my Global Illumination pass. After 24 hours of rendering (progressive), I have a scene that looks like the light cache calculations!

 

My scene is huge (I am doing an entire house & environment, not just a single staged room). I have set up the primary lighting with a Peter Guthrie HDRI (so I know it is great quality), and then a VRay Sun for additional lighting information, linked to the HDRI.

 

I have tried with both sky portals on and off but zero difference. I have turned the windows on and off incase it was a material issue, but nothing. I have ramped up the subdivs in the VRay Dome Light to 128 which has destroyed my render times, but also with no clear advantage.

 

Lighting pass, specular, reflections etc... all nice and clean. Only GI that is a disaster!

 

Not sure what to do or what is wrong. I would really appreciate your help!

 

I'm using Vray 3.60 on 3ds Max 2017. My PC is Windows 10, 2x 3Gb GTX 780 GPU's, Intel i7-8720K 3.6Ghz processor, and 3Gb DDR4-2100 RAM.

[M V]

I find that HDRIs can cause a lot of noise in GI. Have you tried using VRay Next? I remember reading that there was some improvement in that area.

 

https://www.chaosgroup.com/blog/v-ray-first-look-smarter-rendering-with-the-new-adaptive-dome-light

[Scott Schroeder]

What are your GI settings? We can't troubleshoot GI issues without at least knowing what you are using as base settings.

[Francisco Penaloza]

Could you post screenshot of all your render settings??

Also, what's Gi are you using? I am guessing brute force and light cache?? if you are increasing the Dome light subdivs, this means that you are not using the unified system that defaults on VRay 3.x?

I would strongly recommend resetting all settings to default and give a longer time to render and see how it goes. I personally don't use progressive, you could try bucket mode and only adjust the noise threshold.

Also, check how many lights you have in your scene and use that exact number in the probabilistic slot.

 

Regarding HDRI, Peter Guthrie admitted that his original series of HDRI was not as good and everybody thought. They have a wrong white balance and the intensity is not correct, most of the lighting is coming from the sky, instead of the sun. That's why people add a sunlight to compensate colors and shadows.

Guthrie latest hdri are way better, he has a new workflow and they are working as they should be, no need of extra lights.

Having said that on VRay 3.x you should use the portal sky to get better GI inside your room, be sure you don't have gaps in your wall and ceiling to not lose light cache, be sure you have enough light inside your room otherwise your GI will work double or triple.

 

Could you post a screenshot of your scene?

[Andrew Adams]

Could you post screenshot of all your render settings??

Also, what's Gi are you using? I am guessing brute force and light cache?? if you are increasing the Dome light subdivs, this means that you are not using the unified system that defaults on VRay 3.x?

I would strongly recommend resetting all settings to default and give a longer time to render and see how it goes. I personally don't use progressive, you could try bucket mode and only adjust the noise threshold.

Also, check how many lights you have in your scene and use that exact number in the probabilistic slot.

 

Regarding HDRI, Peter Guthrie admitted that his original series of HDRI was not as good and everybody thought. They have a wrong white balance and the intensity is not correct, most of the lighting is coming from the sky, instead of the sun. That's why people add a sunlight to compensate colors and shadows.

Guthrie latest hdri are way better, he has a new workflow and they are working as they should be, no need of extra lights.

Having said that on VRay 3.x you should use the portal sky to get better GI inside your room, be sure you don't have gaps in your wall and ceiling to not lose light cache, be sure you have enough light inside your room otherwise your GI will work double or triple.

 

Could you post a screenshot of your scene?

 

Thanks to everybody for the replies! All points taken... @MV I would love to get Vray Next but I can't afford it. That said, I'm sure the problem in my render is made by my human error rather than software, so I don't think it would help if I am still making the same errors

 

@Scott Schroeder. Point taken, I have attached everything in this reply.

 

@Francisco Penzola, I have tried Brute Force and Irradiance Map with the same issue, but I prefer using Brute Force anyways. I have reset everything to default and disabled the use local subdivs settings but to no avail. I am also using bucket mode, I only use progressive for lighting setups for instant feedback.

 

On the HDRI, I believe I am using a series 1 HDRI, called 1935. I love it for the sunset, his most recent ones don't have many sunsets (I'm doing a Blue Hour Render) as far as I can tell. I am using the sky portal, but that has made no difference either. I have checked the scene and it seems everything is nicely closed up, so that should be ok...

 

Attached are some renders, and all my Vray settings. Thanks again for all the help!!

 

[Francisco Penaloza]

On the Adaptive lights, put the same amount of lights in your scene, Default is 8, if you have 20 lights, please insert that number.

Also on the Light cache you can try un-checking pre-filter.

 

But I think on the first scene your problem is that you have lights inside a glass object, I am guessing this glass is frosted or semi-transparent, this will create more noise that you'll need.

Try placing your lights outside that glass or exclude that geometry from those lights. When you place a lights side a frosted glass this will create a sampling nightmare for any raytracer.

 

On the second view, make the ceiling light a regular VRay light, not a sphere, lights do not illuminate to the back side unless of course, the lights are designed like that in your case I am pretty sure is not. just a regular disk VRay light should do.

 

You should refer to the VRay docs on this, but in your case, since you are doing an interior I would recommend to increase your minimum shader rate, this way more samples will go to clean GI rather than to antialising objects. A number similar to your total AA should work fine. You could go even higher but then you'll start to lose sharpness on your image, do a few tests and see what works better.

 

Remember with the new workflow you only need to concentrate on the number of samples and noise threshold, 24 samples will go a long way, if image still dirty, reduce your noise threshold if still noisy increase max samples and go from there.

 

You could always go min 1 max 100 and just adjust the noise threshold as you need.

[Andrew Adams]

On the Adaptive lights, put the same amount of lights in your scene, Default is 8, if you have 20 lights, please insert that number.

Also on the Light cache you can try un-checking pre-filter.

 

But I think on the first scene your problem is that you have lights inside a glass object, I am guessing this glass is frosted or semi-transparent, this will create more noise that you'll need.

Try placing your lights outside that glass or exclude that geometry from those lights. When you place a lights side a frosted glass this will create a sampling nightmare for any raytracer.

 

On the second view, make the ceiling light a regular VRay light, not a sphere, lights do not illuminate to the back side unless of course, the lights are designed like that in your case I am pretty sure is not. just a regular disk VRay light should do.

 

You should refer to the VRay docs on this, but in your case, since you are doing an interior I would recommend to increase your minimum shader rate, this way more samples will go to clean GI rather than to antialising objects. A number similar to your total AA should work fine. You could go even higher but then you'll start to lose sharpness on your image, do a few tests and see what works better.

 

Remember with the new workflow you only need to concentrate on the number of samples and noise threshold, 24 samples will go a long way, if image still dirty, reduce your noise threshold if still noisy increase max samples and go from there.

 

You could always go min 1 max 100 and just adjust the noise threshold as you need.

 

Thanks! I'll give all those a try and post the results!!

 

For the second render, I'm using a vray IES light... maybe positioned too close to the ceiling? The other ceiling light that can be seen in the reflection has multiple Vray spheres inside each glass bowl... I'm interested in the method of excluding the geometry to give the lights a fighting chance, definitely worth trying!

 

Will let a few renders go tonight and post the results tomorrow!

[Andrew Adams]

On the Adaptive lights, put the same amount of lights in your scene, Default is 8, if you have 20 lights, please insert that number.

Also on the Light cache you can try un-checking pre-filter.

 

But I think on the first scene your problem is that you have lights inside a glass object, I am guessing this glass is frosted or semi-transparent, this will create more noise that you'll need.

Try placing your lights outside that glass or exclude that geometry from those lights. When you place a lights side a frosted glass this will create a sampling nightmare for any raytracer.

 

On the second view, make the ceiling light a regular VRay light, not a sphere, lights do not illuminate to the back side unless of course, the lights are designed like that in your case I am pretty sure is not. just a regular disk VRay light should do.

 

You should refer to the VRay docs on this, but in your case, since you are doing an interior I would recommend to increase your minimum shader rate, this way more samples will go to clean GI rather than to antialising objects. A number similar to your total AA should work fine. You could go even higher but then you'll start to lose sharpness on your image, do a few tests and see what works better.

 

Remember with the new workflow you only need to concentrate on the number of samples and noise threshold, 24 samples will go a long way, if image still dirty, reduce your noise threshold if still noisy increase max samples and go from there.

 

You could always go min 1 max 100 and just adjust the noise threshold as you need.

 

You hit the nail right on the head! I've been doing some tests, and the issue was 100% the light source being inside a translucent object. Once I moved the light source out or excluded it then the scene rendered very clean (for a draft render). So, translucent materials = bad!!

 

However, if I exclude the lamp from the light source, I'm not getting those really nice shadows on my walls. Is there a way that I can keep the shadows, but lose the light source inside the object? A bit stuck on where to go from here really...

 

Thanks!!

[Andrew Adams]

Ok, so first off thanks so much for your help! Your one simple tip has revolutionised my thought process when it comes to lighting! I have shoved in a whole whack of IES lights in the house according to real-world lighting specifications (placement) and my mind is blown. A lot of the noise is gone, and the render is coming out fairly clean on draft settings. Render time has also jumped from 12 hours to a mere 30mins.

 

I can now keep on with the task of adding materials and small details.

 

The issue of shadows with the previous lights (as in my earlier reply) still stands. I also have a weird effect that has happened on the fridge in the new render. It is coming out much darker than all the other wood, making it look weird. It has exactly the same material on it as the other cabinets and has been UV Unwrapped in the same UVW Unwrap modiefier, so it share all the same settings. What on earth would make it render such a different and weird colour?

 

First render is with no lights (troubleshooting). Second render is with new IES setup.

 

[Francisco Penaloza]

Well, glad is working for you.

The problem with a light inside glass is it takes forever to sample, What I usually do is as mentioned earlier, place the light outside of the lamp to illuminate and create a self-illuminate fixture, to fake the light inside the lamp.

 

You can leave the light inside your glass but exclude illumination only. This will render faster and give you less noise to sample.

 

You can also exclude the lamp and use a IES profile light, form that model (find online) this will create the correct shadows. This will render faster and noise free from glossiness.

 

If you can't find the IES or you are using a regular VRay light, then you need to exclude the lamp from 'illumination only' and make the glass part of your lamp transparent only (refractive to 1.0) no frostiness and make it self-illuminate. This will let the light go outside, casting shadows but it won't sample the glossy part of the glass material, also the self-illuminate part will give the effect of the light bulb inside the lamp illuminating the glass.

 

Hope this works for you.

Cheers.