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I could use some pointers when it comes to noise in octane renders. I think I must have read every prominent forum post on the subject of specular noise but still don't have a viable solution.

The scene is quite large and features some distant streetlights, created simply with an emissive material and point light. The closer ones seem to be fine but the further away they are the harder to resolve the seem.
In honesty I don't know if it is a distance issue or perhaps something to do with them being viewed through a glass material. Whatever the issue it isn't solved with samples as high as 50000 (adaptive) and I can't wait 45+ mins per frame. I'll be at this for the rest of my life otherwise.

I'm not using the denoiser pass, it's too blotchy for animation in this case. I may use some post denoising but the render is too noisy to do this at the moment.

Here is the noise and beauty pass plus my Path Tracing settings. Hopefully there is a fix.




Path Tracing Kernel
Samples 50000
Diffuse 8
Specular 24
Scatter 8
ray Epsilon: 0.01
Caustic Blur: 1
Gi Clamp 5
Adaptive Samplin: true
Noise threshold: 0.12
Min samples 512

hot pixel: 0.7

Hi Elsksa,

Thank you for the response, your article was well written too, very informative for sure.
I do often turn to documentation first and do a lot or reading and research before posting.
Your article mentions inspecting passes to see which is causing noise so I will take a look at this and post my results.
It is quite a dark scene and the scale is substantial but noise in shadows is acceptable, also GI clamping sits nicely at 5 without any adverse affects.

I'm not sure why my images won't attach either so I'll try posting them as links...fingers crossed

https://drive.google.com/file/d/1E5aIR7 ... sp=sharing
https://drive.google.com/file/d/1J3csB8 ... sp=sharing

Also yes I'm using the Unreal Engine plugin for this work.

Turn your parallel samples to 1 for Path tracing.

Also for such a scene your noise threshold is a bit high. Start at 0.02 and parallel samples at 1 and then come back with a photo.

If the rays of the distant lights do not contribute to the illumination of the scene, you could try using a ray-switch, so they will only be visible in the camera and refraction. Here`s a scene where you can dive into. It`s not the same scene, but you can see how it could work optimizing the kernel and adaptive sampling. Actually it`s also a nice setup to experiment with bokeh. It renders fairly clean till 5000 samples. You can import the .orbx into standalone. I`m on Octane 2021.1.

Also you can try this:

You aren`t using the denoiser, but if properly used, the denoiser can work really well for these type of scenes.
Check "Fake shadows" in the specular material/window, so rays will ignore refraction + you don`t need caustics I guess.
Normal/bump/displacement maps on the specular material/windows increase rendertimes by a lot!
You can check Thin wall at the specular material to let rays leave the material right away. This speeds up renderstimes a lot.
Make sure the glass/window has a slight roughness.
Increasing the coherent ratio really speeds up rendertime, but make sure it won`t create artifacts.
The aperture-edge also affects the amount of noise.
Make sure the emitters are low poly.
Make sure the emitter isn`t surrounded by a glass bulb.

Yes, for sure. It would take more time to test them all.

Hello All,

Thank you for the very interesting replies. I want to briefly share my findings when it comes to resolving the kind of specular noise that won't resolve witin a reasonable time frame.

The noise was remedied in two main ways with a few additional kernel tweaks.

1) increase the size of light radius. I did this for most lights but had missed a couple and they were causing big problems. If you have a lot of lights in your scene turn them off sequentially until you see the noise disappear, then dive into the light settings. Berar in mind I am taking about Unreal lights so you cant set samples on a per-light basis.

2) Check your materials. I had a couple of materials with very low roughness and very high specular values. This would be fine for Unreal, but not Octane. Toning these values down helped a lot.

3) Path Term Power. I felt that for some of my distant bokeh turning path term power a bit lower than default helped. I set it to 0.2.

Here is the rendered shot. It is just a test for a film so not by any means a finished piece of work.
https://drive.google.com/file/d/1MyX7jf ... sp=sharing