Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] Bug Reporting => [Max] Resolved Bugs => Topic started by: arqrenderz on 2022-07-22, 15:55:55

Title: Volume Materials and opacity light sources Produces wrong results
Post by: arqrenderz on 2022-07-22, 15:55:55

Hi, we have a problem with corona when using light sources (real lights or self illumination)
If you have a global volume material or a volume effect on the scene the opacity maps will have a halo effect visible on the diffuse channel and very visible on the alpha (i have tested cliping the maps in all ways) I have a small scene attached to  see the problem.

Title: Re: Volume Materials and opacity light sources Produces wrong results
Post by: maru on 2022-07-22, 16:58:17

I may be wrong, but it looks like "Transparent materials seen through global volume material (volumetric fog) may look incorrect." described here, the example image with fire:
https://support.chaos.com/hc/en-us/articles/4528311915025-Known-bugs-and-limitations

Can you check if the suggested solution helps in your case?

Title: Re: Volume Materials and opacity light sources Produces wrong results
Post by: arqrenderz on 2022-07-26, 15:50:11

Hi, just tried the solution but what its doing is increasing the volumetric effect to the point nothing is visible and the "bug" is more pronounced, if i lower it the halo disappears but the volumetric effect too.

Title: Re: Volume Materials and opacity light sources Produces wrong results
Post by: maru on 2022-08-31, 13:40:17

I have successfully reproduced and re-reported this issue. Sadly, I did not find any workaround. Perhaps the only option is rendering twice:
- without the fog effects to get correct alpha channel
- with the fog to get the expected beauty

Sorry for the inconvenience. I will report here if we find any reliable workaround or when this is fixed.

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