Author Topic: Fading out a sky?  (Read 1880 times)

2018-08-30, 19:51:44

Br0nto

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I'm attempting to create a day-into-night timelapse scene, and I'm running into an issue trying to get a smooth transition between the Corona sky and a second sky with a starfield light shader.

I currently have the following set of relevant objects:
Sky_Day: A typical sky object with the Corona sky tag on it
Sky_Night_Stars: A sky object with an emissive starfield shader, with a Corona compositing tag that prevents the stars from affecting the GI or cast shadows

The main issue is that I can't find a way to fade out the visibility of the Sky_Day object. A C4d visibility tag doesn't seem to affect it in any way, and while the Corona compositing tag has a "seen by camera" checkbox, that's a very harsh on/off function. Ideally I need to fade it out over a few seconds to cover the sunset period. Turning down intensity and turbidity seems to reduce the sky to a near-invisible level, but it doesn't allow the stars to shine through as I'd hoped.

Any suggestions would be greatly appreciated.

2018-08-31, 00:50:35
Reply #1

burnin

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OK, just checked to be sure...
Nightsky is a large Sphere with Corona Light Material on, IBL/HDRI Emission, Opacity checked & Level animated.
Fading into a day.

alike

(image re-attached)
« Last Edit: 2021-05-21, 19:33:22 by burnin »

2018-08-31, 15:58:16
Reply #2

Br0nto

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Hm, certainly a starmap layering into an HDRI is feasible, but the trick is when you need the sky to interact with the sun. An HDRI won't become any more "daylike" as the sun rises, whereas the actual sky object will.


Is your day sky an HDRI or the actual corona sky object/shader? If it is the corona sky, how did you get it to be totally transparent at the start?

2018-08-31, 23:30:22
Reply #3

burnin

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Hm, certainly a starmap layering into an HDRI is feasible, but the trick is when you need the sky to interact with the sun. An HDRI won't become any more "daylike" as the sun rises, whereas the actual sky object will.

Is your day sky an HDRI or the actual corona sky object/shader? If it is the corona sky, how did you get it to be totally transparent at the start?
Yes, day system is Corona's Sun & Sky, occluded by night sky mesh.



Hummm... Corona's Environment system must really be made much, much easier to become effective for animations. Also got glitches in IPR when Sun tag is attached to Corona Sun. Animating it was quite tedious as IPR didn't refresh all the things all the time, while cinema kept showing wrong values in between key frames and skipped few (as if they weren't recorded? WTF). But kinda made it through the mess. Should explore further...   

(imagery lost)

PS
Another issue is negative HDRI emission reflected on the ground where surface reflection gets rough.
« Last Edit: 2021-05-21, 19:04:38 by burnin »

2021-05-21, 19:17:29
Reply #4

burnin

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simple Corona's Sun & Sky Sunrise using Sun Tag



video @streamable