LightSelect RE workflow question.

[romullus]

I've never used light select, multi light or something similar, nor i feel urge to start using it, but since Corona introduced such feature, i'd like to understand how it can be used. So, let's say i have rendered few LightSelect elements and saved them together with beauty element. What's next? How i should combine them in photoshop? What blend modes to use? Are those REs compatible with Cessential elements? Or do i have to render additional Cshading elements to properly combine final image?

And while we're at it, can somebody shed some light on Cshading elements in general - those are unexplored mystery to me, except for obvious ones, like alpha, albedo and bloom.

[TomG]

Have only just started experimenting and exploring, so I sure don't know all the answers, but some notes on exploration so far!

- So far, I've been using Screen as the blending mode. That said, in my first test I got a slightly brighter end result from this than the Beauty pass (see images). But I am new to this! What I did was render three LightSelect elements, one for sun, one for environment, one for the lamp.

- For use, you can use it to, say, turn lights on and off without re-rendering, or to change the tone and hue of the light sources - e.g. I tried something more extreme than you'd probably want to try with this, to turn the sun into a bright full moon.

Will be testing out more of course!

[Ondra]

to comp it in postpro, you need to use ADD operation in LINEAR color space, then apply gamma, to get 1:1 results. The simplest use however would be to just overlay the beauty with a light select pass in add/subtract mode to make a particular light stronger or weaker

[romullus]

Thank you both, Tom and Ondra! Now it's a bit clearer to me, although that doesn't change my atitude towards light select RE. Maybe it would, if i would see real life example of multilight application... How about official Corona tutorial? ;]

[TomG]

Oh aye, we will definitely have one of those!

Meantime, I moved from dabbling in Photoshop to setting it up properly, exporting to EXR and loading into Fusion and got the 1:1 results as Ondra stated. No official tutorial by any means, but here's a short vid (no sound) showing the test scene in Fusion and some basic manipulations. Has the environment, a CoronaSun, and CoronaLight (kind of like a fill-in flash), and can adjust all these lighting intensities after rendering, change hue or contrast for just one light source, etc. May give some ideas on how it can be used!

Not only handy for correcting things (I know, get it right in the render, right?) but could be great for animation, letting you change a scene from night to day, turn on interior lights, all without rendering the same scene multiple times (and anything that saves render time is always good).

[TomG]

Just to test, I rendered just one frame and made this little animation from it by animating the light select blends in Fusion (this time I added a moon light source so had Env, Lamp, Sun and Moon elements)

[romullus]

Now that's really interesting. One could render simple walkthrough and would have ability to turn on/off lights in post at will. Pretty cool!

[cecofuli]

This remember me my old (very old 2008) project.

LINK
VIDEO

I rendered 9 images (32bit) and mixed in AE. It's the same concept as Multilight.