Render Noise Interior

[Jamesbradley]

Hello all,

I know this is a topic quite heavily discussed on all render forums, and I've read a few topics here on Otoy regarding octane, the problem is, I just can't seem to get rid of it.

I've got a few questions that hopefully someone can answer for me, but first here's a break down of my scene:

Interior bedroom lit from south and east with sunlight coming in through south windows with some sunlight coming in through east.

As for my scene settings I think it's most appropriate to simply upload screenshots:

RenderSettings

These settings produce this render:

Now, hopefully, at this point, it's apparent to some of you why there is so much noise in the corner of the room by the desk. I can not for the life of my figure out why. I've managed to bring my render time to 16-17 minutes per a frame - which I'd be content with if it weren't for the noise. I've tried working with pmc but I haven't really achieved better results, still quite a bit of noise. I've played with the GI clamp from .3 to 100, obviously 100 brought fire flies. I've played with caustic blur, it doesn't affect the render of this room so much but in other scenes I do have glass reflections/refractions of light. Path term I've gone from 0 to 1 with, no real help in denoising. I've brought the samples up to 32000, which seems a bit crazy to me but even with render region hitting 502,000 samples(yup) it's still noisy which seems ridiculous to me and I'm under the impression that I should be able to do this with 2048 samples according to a few tutorials I've tried working through to solve this.

Adaptive sampling has been the biggest help, reducing render times quite a bit because the floor and bed render out nicely enough but the walls are all riddled with noise.

After all this I keep thinking that there just isn't enough light getting into the room or not an appropriate amount. Well, I put portals at all the windows so octane knows where the light is coming from, I've tried increasing the sun power but that doesn't really influence the light so much, I've played with the exposure from 1-15 and the sun power from 1-5. Not much of a difference. I also have the feeling that the sun power should realistically stay at 1 and the exposure is what should change, but I'm open to all methods that aren't too unrealistic.

So, with all this, what would be an appropriate method to reduce the noise?

I'm running a gtx 980 ti, 64gb ram, 5820K CPU.

Thanks so much for any help or references that can help me with this!

[grimm]

I would probably drop the portals and just open up the wall behind the camera (if you can) and see how that helps.

[Jamesbradley]

Thanks for the tip, unfortunately I'm not sure If I can work with that because the ultimate animation is a seamless walkthrough, and this particular instance pans 180.

[mib2berlin]

Hi, is the wall material 100% white? If yes this can produce noise.
Iirc I had the same problem some time ago and I set color to 70% white and add a emission node with very low value.
Material looks white and also send more light in to the room, this reduce noise.

Cheers, mib

[Jamesbradley]

I read a few suggestions regarding white walls and how that can bring in noise to a scene, but the material is not 100% white and also contains a plaster/wall texture bump. I've thought about adding a little emission to the material but it didn't play so hot when I did it initially. I'll try giving that another go.

I've adjusted the material so that the diffuse leans more towards grey just to test out color contribution to noise, even at 900,000 samples there's noise.

[bepeg4d]

Hi Jamesbradley,
Portals in OctaneRender does not tell where the light is coming from, but where to go to reach the environment and finish their work. They work pretty well, but only when the opening is very very small. In normal interior scenes, it is much more efficient to use a 0 opacity emitter material instead of Portals in opening, in general with high kelvin temperature to simulate the contribution of indirect light from sky.
About Adaptive sampling, please increase the Min samples value at 640 or greater to help the kernel in the noise definition, and set the Expected exposer to 5, like the exposure value in Camera Imager node.
ciao beppe

[mib2berlin]

Hi Jamesbradley, may it is possible to upload the scene without interior as .orbx.
It is mostly better to have a look at the scene to help you.

Cheers, mib

[Jamesbradley]

Thanks for the tips! I'll try out a 0 opacity emitter with a high temp. similar to environment lighting. Boosting the adaptive sample min samples to 640+ will only ensure the whole scene undergoes a minimum 640 right? From my renders so far it seems the whole scene is rendering until 2000+ samples, it's only at about 4000+ that there's a noticeable peak where adaptive sampling kicks in. Will try it out and I just adjusted the exposure setting.

Mib, here's the orbx scene, thank you so much for helping me out with all this! I'm really looking to bring my render times below 10min because I'm aiming for a 1 minute animation at 24-30 fps.. at this rate its going to take me over a week to render..

https://www.dropbox.com/s/9k1khpk0zrerc ... .orbx?dl=0

[mib2berlin]

Hi, make a few tests and got 22 minutes at HD resolution with my old GTX 760/670.
I change following settings:

Diff/Spec depth 6
Caustic blur 0.01
Clamp 1000000

Noise threshold 0.02
Min AS 64
Expected expo 0

I think with a different wall material you can get better results but had not more time to investigate.
With your card you should get about 10 minutes.

Cheers, mib

[Jamesbradley]

Thanks so much!! Would you be able to run through your thought process for optimizing the scene?