Interior rendering problems

[Muhammed_Hamed]

Hi Muhammed, thanks again for your comments. Window glass is already excluded from GI and lighting is by a hdri on a domelight, no Modo environment. Noise threshold of the adaptive sampler is on 0.007. I guess the only way to get it cleaner is lowering the noise threshold, i dont know if adding an additional light inside gives a better GI solution since the noise problem is only on the ceiling and the two walls, the rest of the picture has a very good GI quality.

Now i have to work on the textures, because when i switch them on i get a lot of additional grain.

Let me know if you need help. If a material is causing issues, screenshot the sample rate pass here

[Muhammed_Hamed]

I guess the only way to get it cleaner is lowering the noise threshold, i dont know if adding an additional light inside gives a better GI solution since the noise problem is only on the ceiling and the two walls, the rest of the picture has a very good GI quality.

This is the advantage of this workflow, you only change the noise threshold to get rid of noise.
Direct lighting will definitely help as well like what Boyan suggested, but you should be fine with portals as your windows are very big. Adding area lights is more about lighting/mode more than dealing with noise.

[boyan]

I want to thank you for helping us, Muhammed !!!

[ingoerik]

"Replace the portals with Area Lights, Enable Environment Map and add an HDRI texture map to it next disable Indirect Light option from the properties menu, change the Light intensity of Area Light and let's try how clean render will be."

Hi Boyan, when i understand you correcty you'd like me to use arealights instead of the hdri to light the interior ?

So, here is the next one, Brute Force with Muhammeds settings (adaptive Sampler 16,1,32,0.00 and Portals, BUT NO DomeLight, just normal environment. Walls and ceiling have now a stucco imagemap to see how it works with the noise, rendertime is nearly 11 hours.

Dear Santa from ChaosGroup, please add an EIS to DomeLights that is as good as Modos EIS I still wonder why i get DomeLight noise on the walls and the ceiling, but not on the floor.

[boyan]

Nope, you still used the HDRI with Environment map (this is dome light, also btw) but EIS is important to get a cleaner result. But, I am sure that if your GI RE is clean or at least less noisy than the Light or Direct Light, why is that!!! well, because you use portals, which are like a magnifier of GI and zero direct light. That's why recommend you to use Area light on windows. You can see the similar technics in 100% of the magazine's renders and there are two reasons for that 1. Direct light noise 2. More contrast and dynamics, emotion into the renders.

Cheers,

[ingoerik]

So if i use HDRI on a DomeLight (means EIS) and Area Lights in the windows the noise from the DomeLight has less contrast and looks a bit better, but rendertimes get longer. Portals act as a direct light, they just sample the incoming colors from the GI, kind of a textured Area Light.

When i avoid direct light and bruteforce rendering i get a completly noisefree picture, that means an Irradiance rendering and hdri only in environment, without domelight. But of course the contrast from the hdri lighting is low and its hard to get clean shadows.

[boyan]

Well, if you're going to use Area light is better to change the Image sampler to use Irradiance map rather than Brute Force. For IM you can set Medium or High and L/C for use 2000 samples. You have an animation I suggest you use BF/BF. Btw, are you sure that render time is longer when you're using area light?

[Muhammed_Hamed]

Thanks for the update!
Compare the sample rate render element from your last render to the one that you used portals with a domelight. There is almost no noise on your walls using portals.
Did you do a full render with materials with this approach?
Using area lights I wouldn't rely on an HDRI at all. It will probably bring noise back. It would also be better if you post your GI and direct lighting RE
By the way, Vray is way faster than Modo for this kind of scenes. 11 hours render time is very odd honestly, unless you are working on a laptop?
What CPU do you have?
Is it possible to upload this scene? I will try out few lighting setups and post render times here.

[Muhammed_Hamed]

Well, if you're going to use Area light is better to change the Image sample to use Irradiance map rather than Brute Force. For IM you can set Medium or High and L/C to 2000. You have an animation I suggest you use BF/BF.

From my testing, BF is nearly as fast as IM(medium-high presets), but it is way better for shadows.
11 hours render time for this scene is odd.. As you see in his sample rate render element, Vray is having a lot of trouble on walls.
Now, compare this to the sample rate he posted earlier using portals and a domelight. The walls are very clean.

[ingoerik]

Hi Muhammed, well there is not that much noise anymore because i haven't used a domelight, and if i use Irradiance instead of Bruteforce there is no noise, but than i get problems with the shadows. The noise from the domelight is the big problem.

My computer is an old 2,8GHz Core i5, on that i get a clean Modo rendering in half the time (that was an irradiance rendering). So the 11 hours for a BF rendering are quite okay, especially if i add the denoiser. And as you mentioned its much easier to work with BF instead of IC, and if i put the final image on a renderfarm i can lower the threshold if necessary ... or render in higher resolution and scale down later.

[ingoerik]

So here are the indirect and direct diffuse shading RE from the above rendering.

[ingoerik]

The problem is VRays direct light quality, here are two diffuse direct REs from the room lit only by area lights in windows, rendering is irradiance. One with the default 8 subdivs and one with 256 subdivs. Interesting is that the higher quality picture renders a bit faster.

[ingoerik]

Okay, the last pictures, thanks for all the help. Brute Force with Muhammeds settings (adaptive Sampler 16,1,32,0.007 and Area Lights, environment as DomeLight), AreaLights and Environment have a subdiv of 16 instead of default 8. Walls and ceiling have a stucco imagemap again, rendertime is nearly 8 hours.

We got noise in the renders coming mostly from the Domelight+HDRI and of course the BruteForce renderings. We get some more noise from the exterior (replicated grass and hedges ... and the trees). Portals are not that useful, AreaLights help to clean up the noise a bit. So noisy BruteForce is easier to handle, especially when you put it on the renderfarm, Irradiance is faster but you get annoying noise on the walls on the right that needs a bit get clean. Comparsion to Modo its a bit difficult because i never used BruteForce, but Modos IC is faster, or cleaner, depending on the settings. I've got a clean IC in Modo in 5-6 hours, i got a rendering in VRay in 6 hours that has definitly still noise.

Keep in mind that this testscene has everything to slow down renderings, a fur carpet, a glass chandelier, replicated greenery outside through glass windows, and a HDRI for lighting.

[boyan]

Howdy,

Don't use the local subdivs of the lights. My suggestions: 1. Image Sampler - Adaptive 100;1 100 , threshold 0,008 || GI IM/(High) LC; 2. Materials - V-Ray Mtl; 3. V-Ray Main - Color Mapping rollout - Multiplier - 2 (this will make you image natural bright)

Cheers,

[ingoerik]

Hi again,

boyan, why shouldn't i use local subdivs, since the noise is coming only from the dome light its best to just change that quality ? Seems to me like an overkill to use the sampler for it.

So, after endlessly watching renderings i found out that obviously the glass chandelier slows down rendering a lot. Glass has already a Modo Shader with indirect light switched off and i can lower the reflection and refraction settings a bit as long it still looks good.

Than there are the windows, everything behind the windows renders slow. That glass has a Modo Shader with indirect light switched off too, double sided is switched off to (should be the default setting), any hints to make windowglass render faster ? What about "use irradiance map", should that be switched off in the material ?