How To Animate Corona Light Mix From One Frame

[piotrus3333]

Bit of a gripe - come on Corona Team - this one was sloppy. Please consider updating the video: https://www.youtube.com/watch?v=U9Ym2QHTm4Q.

Do not use Gamut node on Fusion page, just select your exr layers. Use Adjustement Clip on top of your lightmix with ACES Transform effect. Adjustments to lights do on Color page.

[TomG]

Your example shows ACES OT applied, whereas we were doing no tone mapping in Corona to preserve a linear workflow (also do remember that ACES OT is NOT an ACES compatible workflow, and does not create ACES workflow files - it simply applies a curve that is one used in ACES to "sweeten" the image).

Anyway, there are certainly more ways than one to achieve an effect for sure so if you prefer your workflow and it gets you the results you are after, that is cool! Good that you shared it here too, ty!

However, we wanted to keep it to Fusion which is probably more intuitive for Corona users than the Color page (and easier to keyframe, I find, than doing things on the Color page). The Color Corrector node in Fusion is very similar to the Color Correct in Corona, which for someone new to Resolve may mean it "makes more sense" right away. We also wanted to avoid touching anything ACES at all in Resolve :)

[piotrus3333]

Apologies up front but "bit of a gripe" becomes more of a rant I guess.

Reality is after Corona users learn from the Corona YT channel I get to work with some of them. If I manage to straighten things up now that means less hair pulling later on. Energy spend in the name of education.

You were doing no tone mapping? ok, but who is doing no tone mapping while rendering images in Corona? in what scenario this is the way to go?? When the image hits the screen it needs to be viewed with a proper transform. What is the default view transform in Corona? ACES OT. So lets use (almost) the same transform in Resolve, shall we? Corona crowd is a "defaults crowd", and it's ok, no need to fiddle with defaults. ACES OT is a great default.

You were preserving linear workflow? And then breaking it with gamma (Gamut node) before adding the lights together? Do LightMix the way Corona does it first (gain and multiply by colour) before anything else.

Regarding Fusion page over Color page - ok. More complicated and view lut would be welcome. On the Color page you see all your lights and the final result (Adjustement clip). But that is just preference, nothing wrong with doing it through Fusion.

edit: "We also wanted to avoid touching anything ACES at all in Resolve :)" - well, as the "sweetening curve" was named ACES OT - the cat is out of the bag now. And as the curve ACES OT was based on is build in Resolve - why not use it? Good defaults are good defaults.

[TomG]

Most of the tone mapping breaks linear workflow, that is, you can't then linear add the elements back together to get the correct result as some clamping has already happened. If you plan on doing LightMix in post, or pretty much any sort of corrections or grading, it is generally best to have no tone mapping in Corona, as you've moved that over to the post software (that is, if you are going to move one part over, you really have to move it all). This is similar to getting maximum control out of LightMix by keeping all lights white and of similar intensity - it does mean the Beauty pass is now nowhere near a final result, but it opens up the full flexibility of LightMix adjustments without running into noise, etc.

Lots of good advice here of course, and we're not looking to teach Resolve in detail, just to get people started with something that gives them the same results as the VFB as their starting point. We'd then hope they'd dive in to learning their post software in full to find all ways of doing things, this approach (given to me by some folks who use Resolve) certainly got me to a point where I got the Beauty back before going ahead to make LightMix style changes!

If time allows we might explore other ways of carrying things over from Corona to Resolve, but we really don't want to get into teaching other software so much as just let people know the possibilities and get them started, and we have lots of other Corona-side things to make tutorials on too. Cheers!

[piotrus3333]

It’s not about teaching Resolve. It’s about basics of cgi. Addition, multiplication and displaying the result on a screen. Fallowing the video it is impossible to get the result matching what you get from Corona’s LightMix.

[piotrus3333]

I'll try again as I can see I'm not getting through. So please let me reiterate my concerns.

Why is an official youtube tutorial from Corona team claiming that 0.5+0.5 should equal 1.471?

What is gamma transform doing in the middle of LightMix??

[TomG]

Because we are a Corona channel, not a Resolve channel :) This gave us the results we wanted, after some advice from Resolve/Fusion users when we were initially not getting usable results, so it's the workflow we've showcased here. The only one? The absolute most correct one? I couldn't say, but if it gets people started with usable results, then mission accomplished!

[piotrus3333]

As a matter of fact there is only one correct way of doing the LightMix. And most Corona users should be pretty familiar with it:

[maru]

I don't get the gripe/rant approach here. With your statements like "come on Corona Team - this one was sloppy" you make it sound like we made some horrible mistake here.

This is just a simple tutorial for beginner users. It's title is "how to animate Corona LightMix from one frame" and that's exactly what it shows, without any technical details. Since this cannot be done directly in 3ds Max+Corona, we are showing how to do it with 3rd party software. It's not a Fusion course, so we are not spending too much time on it or explaining what are the common Fusion issues and solutions. If you are an advanced Fusion / other compositing software user, you probably don't need a tutorial like this and you know all the tricks already.

If you want to composite things rendered in Corona - disable ACES OT in the Corona VFB. Yes, this is true, otherwise you will not be able to add the elements and get the expected results.

We are showing that if something looks darker, one solution is to apply gamma correction. That's it. It works. No need to overcomplicate it or provide extra technical explanation.

If a beginner users follows this tutorial - they will get the same results as we are showing. No need to overthink this.

[piotrus3333]

True, I do consider this one a "horrible mistake". O rather how I would put it: unacceptable quality control. From Corona team. Just baffling. Hence the rant and overall tone.

And it is not about how you do things in Resolve. Yes, it is surprising why you did not show how to do it in Photoshop (quite an obvious choice I guess for "a simple tutorial for beginner users") but there is certainly nothing to complain about regarding the software chosen for the tutorial.

If you want to composite things rendered in Corona - disable ACES OT in the Corona VFB. Yes, this is true, otherwise you will not be able to add the elements and get the expected results.

are you considering the output from Resolve - adding together gamma corrected elements - an "expected result"?? I have to argue here that an expected result is "exactly what you see in Corona" - nothing less, nothing more.

We are showing that if something looks darker, one solution is to apply gamma correction. That's it. It works. No need to overcomplicate it or provide extra technical explanation.

Is that a bad joke? Just gamma it if looks too dark?? In an official tutorial of Chaos® Corona??? How on Earth is doing LightMix not the way Corona does it not overcomplicating it? Beginner user uses default Corona settings. Beginner user knows how to use the LightMix. Just show in the tutorial how to do the same in post. Same steps, same controls. Simple, right? Instead you show that someone making Corona tutorials does not know how Corona works.

[piotrus3333]

TLDR version.
What aforementioned "beginner user" sees in Corona and what he gets fallowing the tutorial:

[TomG]

We know how Corona works. The question is how to achieve a similar result in post. Photoshop is no good, as you can't create animations with it. Also Photoshop does not have this problem, with EXR-IO installed, on loading the EXR it displays correct and is not too dark. The whole point here is not "how to do LightMix in post", it's "how to create an animation in post by varying the LightSelect elements" so you are creating an animation that lets you turn on and off lights, change their color, and their intensity, rather like in LightMix... just animated.

It would be very hard to animate the individual layer in Resolve if that layer is too dark, that is, does not have it's own correction applied and corrections were only applied to the final composite result. And I am not sure if your proposed set up DOES give a more accurate result or not - this was very much a bonus tutorial that already took far longer to create than anticipated due to fixing things like the imported EXRs being too dark to work with, and we have other, more directly Corona related content we need to focus on. As noted, the idea here is to make people go "Oh! You can animate it?" and show them a quick and simple way to do so, and then it's on them to learn more about Resolve or whatever their chosen post production software is if they find results from this route are not to their satisfaction - though the results were just fine for me, I was able to understand what was going on and get the results I would want from "animating LightMix" just fine :)

Anyway, do please feel free to create and post your own tutorial showing alternative and possibly "more correct" methods. YouTube is a big place and has room for lots of ways of tackling a problem!

EDIT for your new post - sure, but since it's an animation and they will be tweaking everything anyway, an identical match is not likely to be needed. After all, hue, exposure, mix strength, and more, are all going to be changed and changing.

[piotrus3333]

ok, you convinced me.
if the tutorial was not about "how to do LightMix in post" but how to animate some layers then you are right - it's all good, it's animated now. success.

let me point out two last details.

the way both of you write about "imported EXRs being too dark", this being a "problem" and "fixing" it that "took longer than anticipated" does not inspire much confidence. it's not a problem: it's a view transform. Corona has it, Photoshop has it and you will find it everywhere where you view linear colour on a display.

and second detail - yes, you can animate in Photoshop. would be perfectly sufficient for this tutorial. just imagine the time saved on "fixing problems".