Refractive Caustics Issue

[drew]

Hi legends,

I have an issue. I am doing a render for a client of their Rosé bottle. I'm using Refractive Caustics on the glass and wine materials (as you would expect).

Really happy with results - but when you get up close, the caustics in certain areas are producing a bizarre pattern. Almost like a bump texture.

I have burnt too much time trying to solve this, so here I am. GI/AA adjustments in render settings didn't help.

The scene is primarily lit using a 32bit HDRI, but also a plane with a light material attached (with gradient edges to emulate a softbox)

Below is a series of screen shots to help demonstrate. They're screen shots of the final 30pass with a Corona High Quality Denoise Pass.

Oh, and I'm getting a few fireflies but thats the least of my concerns at present.

Any advice would be much appreciated.

Cheers from Australia.

[Beanzvision]

G'day! Are you able to share your scene with us at all? If so, please use the link in my signature below. Also, how does it look without caustics, is the any displacement in the glass?

[drew]

Hey Beanzvision, I couldn't use your link for some reason, but try this link...
https://drive.google.com/drive/folders/1oF_GIw-dqTfN_uwzRNTOSe4N6b6-69MA?usp=sharing

[Beanzvision]

Hmm, ok. Access requested

[drew]

I believe it's related the the HDRI image I am using. I don't seem to get it with others when I've tested them – but I really like how this one lights the scene. So strange.

[Beanzvision]

Hi, so I have checked this and it seems to render as expected. Here's my example.

[drew]

Thanks for looking into it. It looks like you're experiencing the same anomaly also.

[Beanzvision]

Can you try disabling the Adaptive light Solver to see if that helps. I rendered the bottle with just a default material and noticed the issue even more. After switching this off, the artifact was gone. I hope this helps.

[maru]

Which version of Corona are you using? There were some caustics-related fixes in V10.
Also, remember that caustics don't work correctly with region-rendering, so you need to render full-frame to see what they really look like.
And lastly - just a shot in the dark - are you using some kind of denoising? Those artifacts look like something caused by that.

[drew]

Thanks Maru, I'll check out corona v10, I'm using v9.
The attachments in my initial post were from a full-frame render with 30passes.
It was occurring during each pass, but cleared very slightly with Corona HQ Denoise.
No other denoise applied.

[drew]

Sadly no luck with V10. I might look for another HDRI, but it still doesn't address the problem. Time to move on. Thanks for the advice anyway.

[Beanzvision]

I see you are also applying an HDRI to a sky object as a light material rather than loading it from within the sky object itself. Can you also test this? I feel I'm getting expected results with this scene as bump etc will be more noticeable at grazing angles.

[Beanzvision]

When rendering with just a ''clay'' like mat, this is more noticeable. The only way I could get rid of this was by unchecking the adaptive light solver.

[drew]

Awesome, thanks so much! Im going to try this.