Caustics Noise.

[Mokiki]

Heyho,

I did a similar post like this a while ago which also had to do with the amount of noise inside of caustics. I was referred to the standard spotlight method which worked without a problem now. Some time later I have to do caustics for a client. And wanted to use the same method again. But this time I can't get any noise free result even with caustic subdivs above 10k.

The scene is very simple some a spline shaped like a torus knot which three tubes following it with some twists light by different vray lights (caustics disabled) and 1 Spotlight from the camera position which I use for the caustics.
The Attachment Light Settings:

include: nothing
intensity 800
falloff inverse square
start 1 cm

Vray Light properties: Caustic Subdivs 8k; Caustics Multiplier 27000

Inside the Render Tab:
Caustic Settings:
Multiplier 4
Search Distance: 20
Max Photons: 60
Max Density: 0


Am I missing something here or do I really have to go even higher with my subdivs to get a good result.

[tashko.zashev]

Hi Ralph,
Would it be possible to send your scene or a part of it, to vray@chaosgroup.com, so we will be able to see more closely your issue?
Please specify also your 3DS Max and V-Ray version that you are using.

[Mokiki]

Sure thing email is sent.

[tashko.zashev]

Hi again,

Note that caustics needs very high subdivision values to get smooth/clean result.
I have prepared a simple preview with different settings:


Note that increasing the Spot light subdivisions to very high value will leads to a huge memory consumption (for an example with 15000 subdiv ~ 4,5Gb photon map).
In order to get the best result with less memory and good render time, i can advice you to find the best configuration, between the Light caustics subdiv. and "Max photons" value, for your scene. The "Max photons" option will make the image more blurry and smooth.
Also you can always save the caustics photon map to a file, then play with different values for "Max photons".

Hopefully this will help.

[Mokiki]

Thanks for the tests! I wasn't sure if upping the subdivs is the only way to get better caustics but this seems like the way to go. I really appreciate the help!

[vlado]

You can save memory if you increase the "Max. density" parameter too - it will cause photons that are close by to be merged.

Best regards,
Vlado