issues with rendering octane spotlight with smoke

[Rob644]

Hi,
I tried to render spots but I have often problems with quality.. I tried to render with 16000 samples but even than, that makes me noise.

here is my problems :
-when I have the spotlight blue, that makes me noise in the right side of the picture.
-Makes strange roung lines
-the back light makes another color to the blue spotlight...

I tried :
check AI light
check AI light update
Max samplles 16'000
140 sampling rate on the spotlight
use primitive on the spotlight

I have often that with spotlight, difficult to render...

here is my c4d file
https://www.dropbox.com/s/9dog3dmaygppd ... e.c4d?dl=0

maybe someone can help me ?

[jayroth2020]

You need to increase your Max Overlap Volumes setting (you have it set to 4). It can go up to 16 at present. That will improve what you see significantly, but it will not resolve the situation completely, because you have more than 16 volumes with all of your lights. If you cut down on the spotlights, you should be able to get the volume count under the threshold.

All that said, you may want to approach this scene differently. Can you build up your image in layers? The rear spotlight could be a separate element, and you are not seeing a strong shadow from it in the image you posted.

If not, then I recommend that you convert your spotlights to area lights, and use a Spotlight Distribution instead, and enable the Volume object that you currently have disabled. You can then dial in the Spotlight Distribution settings to match the look you currently have. Note, however, that the look will be different, though you can get it close.

You can also use the Standard Volume instead of the Volume Medium in your Volume object. Again, that will also require tweaking. That's all I can think of for now...

[Rob644]

ok Thanks.
so I tried the Max overlap volumnes to 16 but I didn't see a difference unfortunately. I really see a difference ?
Yes I can export in different layers, is not really best but I can.
The spotlight is more complicate to create good renders not ? sure I can convert to area light but how can I make this light spot effect ? Spot distribution I mean ?

[jayroth2020]

In your scene, there is a difference when you increase the value, but it does not remove the issue as you have more than 16 overlapping volumes.

To add the spotlight distribution on an area light, just select the light tag, and in the Main tab attribute manager for the tag, add a Spotlight Distribution in the slot. You can do this by clicking on the arrow button, and choosing Plugins > c4doctane > Spotlight Distribution from the pop up menu. Then go to the Attribute panel for Spotlight Distribution and set up the shader. Try the various options until you get the behavior you need.

[Rob644]

ok that's a really nice option. thanks! I didn't know about the spotlight Distribution
just sad that we can't use the spotlight light. I have often problems with.. difficult to use it

[elsksa]

ok that's a really nice option. thanks! I didn't know about the spotlight Distribution
just sad that we can't use the spotlight light. I have often problems with.. difficult to use it

I personally prefer to refer to it as the Spectron Light. It's basically an optimized volume spotlight, different from an actual Octane regular light with a spotlight node to its distribution slot. I've covered both here (Lighting) and here (Volume)

[Rob644]

Hi, thanks for this information. But it's like you said, strange to understand how it works Spectron... we have to use primitive and activate AI light right ? but I don't have to use the "Distribution Spotlight" in the Distribution section ? how can I use it as spotlight ? just to be sure to do the right thing. but for sure, looks interesting, and thanks for your links!

[elsksa]

Indeed, a Spectron Light doesn't require a spotlight node to be plugged into the distribution slot. This is primarily intended for "regular" area lights.

[Rob644]

Hi,
ok so I tried different options. but still have this noise near the origin of the light spot.. that happen to me for long time and still don't find how to do it..

I tried :
-Spectron
- high samples on Max samples
- high samples on the light tag
- Remove all other lights

here is the link of the C4d file and the exemple :
https://www.dropbox.com/s/nv3lhvj3csedt ... s.c4d?dl=0

Just a small thing, also I add a post glow processing on octane. with the denoise it change radically and make the flare much lower than without denoise. maybe you know why ?
Without denoising :

without denoise

With Denoising :

With denoising

[elsksa]

- high samples on the light tag

Not a light-sampling parameter! It's a common misconception. The Light Sample Rate (key word is "rate") is a "priority sampling" option, put simply. It is covered on the aforementioned page Octane Lighting (from one of my previous replies). There isn't any advertising on the site. If I insist on consulting it, it's solely for acknowledgement purposes.

Just a small thing, also I add a post glow processing on octane. with the denoise it change radically and make the flare much lower than without denoise. maybe you know why ?

One has to keep in mind that the denoiser has to denoise from a scene as optimized and properly sampled as possible. It shouldn't be relied on for drastic denoising caused from "noisy scene" (aka "lack of samples"). I haven't used the denoiser with PostFX, it possibly wasn't designed for including PostFX? I have to check on my end. In some cases, compositing (even rudimentary) might become necessary for denoising, handling glow/bloom, etc. Some post denoisers become more efficient with AOVs data additionally to the "beauty render". Having in-rendering denoising/PostFX is handy for quick iterations and drafting.