Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] I need help! => Topic started by: thomaslivings on 2021-03-31, 23:25:44

Title: Exclude from fog?
Post by: thomaslivings on 2021-03-31, 23:25:44

I have an animation scene with CoronaVolumeMlt in the Global volume material slot in the Scene render panel. Which is how I'd normally do fog.
I need to put a card in the background with a mountain range on an alpha. Im using a light material with an opacity, so it ignores the global lighting (HDRI).
I get a weird effect on the transparent parts of the mountain range. Is there any way I can have the mountain range not be affected by fog in the render?
Its difficult to composite in a separate pass because I like the glow effect of the sky against the scene when the mountains are not there.

I think one spolution would be to do the fog in a volume (instead of global) and have the mountain card outside of the fog volume? I am sure I used a fog volume way back, but I cant remember how to do it...
Any help apreciated!

Title: Re: Exclude from fog?
Post by: aaouviz on 2021-04-01, 10:16:44

Just use a Corona Distance node to have no fog near the mountains. Should be pretty easy if I understand you correctly...?

Tip; don't use the mountains themselves as the distance object, but a large primitive sphere/box which is non-renderable - this should save on 'distance' calculation time as presumably the mountains might be a bit geometry heavy

Title: Re: Exclude from fog?
Post by: thomaslivings on 2021-04-01, 15:00:49

Thanks for the advice! I just used a regular shader in the end instead of the light shader, exposure worked out ok anyway. The mountains are just mapped onto a topless/bottomless cylinder, so not heavy. Im not familiar with the distance node, you mean like a gradient ramp set to distance z from camera?

Title: Re: Exclude from fog?
Post by: romullus on 2021-04-01, 15:20:45

Quote from: thomaslivings on 2021-04-01, 15:00:49

Im not familiar with the distance node, you mean like a gradient ramp set to distance z from camera?

Then you should definitely give it a try. You can do many things with Corona distance map. Here you can find the description and few examples: https://coronarenderer.freshdesk.com/support/solutions/articles/12000017221-corona-distance-map

Title: Re: Exclude from fog?
Post by: thomaslivings on 2021-04-01, 15:33:20

[/quote]

Then you should definitely give it a try. You can do many things with Corona distance map. Here you can find the description and few examples: https://coronarenderer.freshdesk.com/support/solutions/articles/12000017221-corona-distance-map
[/quote]

oooooooh, thats super-nice! Every day's a school day! Thanks again.