Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] I need help! => Topic started by: hiramiya on 2023-06-23, 06:35:48

Title: I would like some help regarding the color reflections.
Post by: hiramiya on 2023-06-23, 06:35:48

I am creating a scene using the "reference image" attached, but when I actually create it,
 the ceiling color, like in the "corona renderer," reflects too much of the floor color,
which becomes visually unpleasant. How can I achieve a more accurate reproduction?

(https://cdn.discordapp.com/attachments/1094520413549240330/1121664069708042411/screen_shot.jpg)

Title: Re: I would like some help regarding the color reflections.
Post by: davetwo on 2023-06-23, 09:00:40

You need to make the floor a ray-switch material. Have a look in the corona docs for more info: https://docs.chaos.com/display/CRC4D/Corona+Ray+Switch+Shader

Title: Re: I would like some help regarding the color reflections.
Post by: hiramiya on 2023-06-23, 11:21:42

Thank you! I'm glad it worked out for you!

As for your question, is it difficult to reproduce it using just one material in the current situation?

Title: Re: I would like some help regarding the color reflections.
Post by: romullus on 2023-06-23, 11:41:54

Quote from: hiramiya on 2023-06-23, 11:21:42

Thank you! I'm glad it worked out for you!

As for your question, is it difficult to reproduce it using just one material in the current situation?

Not at all, you just need very carefully and precisely measure every characteristic of every material in the reference object, make sure that all the lights have precisely calculated intensities, colour temperatures, spread angles and so on. Don't forget to take into account characteristics of camera sensor and apply exactly the same tone mapping and post processing like in the reference photo. After that, i think Corona will have no trouble at all to provide you very accurate rendering on its part. Alternatively, you can save yourself from a lot of headache and do a little cheating, like it was suggested by davetwo.

Title: Re: I would like some help regarding the color reflections.
Post by: maru on 2023-06-23, 11:47:50

Quote from: davetwo on 2023-06-23, 09:00:40

You need to make the floor a ray-switch material. Have a look in the corona docs for more info: https://docs.chaos.com/display/CRC4D/Corona+Ray+Switch+Shader

Is it because the floor is made of rayswitch material in reality? :)

Title: Re: I would like some help regarding the color reflections.
Post by: burnin on 2023-06-24, 18:01:24

Just an observation...
 I'm starting to find this being an issue connected to some sort of 'bias' - maybe part of one that can be observed in surfaces/shading when camera (eye ray) is hit at very low angles (then it tends to darken surfaces) while with GI parallel surfaces it tend to 'over-bleed' opposite ones... hmmm...


PS.
Yes, both can be 'corrected' via 'RaySwitch', but from user perspective better fine tuning (less bias) would be preferred.