Author Topic: Tonemapping - Plz Halp  (Read 12927 times)

2020-05-01, 17:08:01
Reply #90

agentdark45

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I really did not create this thread with the intention of comparing FStorm and Corona Renderer...

I think people are making the comparison because Fstorm has the best tonemapping algorithm out of all common rendering engines at the moment.
Vray who?

2020-05-01, 17:57:32
Reply #91

Fluss

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I really did not create this thread with the intention of comparing FStorm and Corona Renderer...

I think people are making the comparison because Fstorm has the best tonemapping algorithm out of all common rendering engines at the moment.

The thing is, as Juraj pointed out, we're not even sure the "Fstorm look" can be attributed to tone mapping only. So further investigations need to be conducted before making such a claim.

2020-05-01, 21:02:09
Reply #92

cjwidd

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Well, regardless of the comparisons, there are a lot of interesting comments about *tonemapping* that are emerging from those comparisons, so that's good 👍

2020-05-01, 22:11:29
Reply #93

agentdark45

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I really did not create this thread with the intention of comparing FStorm and Corona Renderer...

I think people are making the comparison because Fstorm has the best tonemapping algorithm out of all common rendering engines at the moment.

The thing is, as Juraj pointed out, we're not even sure the "Fstorm look" can be attributed to tone mapping only. So further investigations need to be conducted before making such a claim.

Maybe not attributed solely to tonemapping, but I would hazard a guess it's at least 50% of the reason. Please look at the highlights and roll-off to extreme black in the examples posted earlier by lolec - that is one aspect that is definitely down to tone mapping. Colour behaviour differences could be due to the internal colour space/custom matrix, I agree.

I would urge anyone who has doubts about the highlight/black crush issue to test it for themselves in 1:1 comparisons as Fstorm is fully functional (with watermarks). You will not get the same level of pop/photographic contrast in Corona (without external post processing), without sacrificing either blacks or highlights - I would almost liken this to differing dynamic ranges of cameras as an IRL analogy.
Vray who?

2020-05-02, 00:47:05
Reply #94

lolec

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There is no way 50% of the realism coming from the Fstorm community is because of the tone mapping. Install Fstorm and try it. See if your images look 50% more realistic just like that. They won't.

My guess based on the actual tests I did and trying to figure out the Fstorm phenomenon: 

1. It is easier to get a baseline good result because of the default settings, easier to take that to photoshop than what corona gives as default. Less settings to fiddle with, less to learn in order to get a good result (Great and excellent results are just as hard IMHO)
Other than the LUT default examples I provided earlier, here is another one for bokeh:


You can argue it is stupidly simple to just move center bias to 0.5 instead of 0. But it is SIMPLER to do nothing.

2. Thanks to gaming, people already have powerful GPUs installed, so while a 7k USD PC might provide little speed distinction between a threadripper build vs multiple 2080Ti build, new artists are more likely to already own the right hardware to take advantage from Fstorm, thus learning it faster. In the early days of learning, when the curve is steeper, 50% faster results means you are learning and iterating twice as fast. My theory is that you can become GOOD much faster with Fstrom with the hardware you already own. 

3. Totally subjective based on MY experience and appreciation, but settings seem to be "dumbed down" example: White balance is based on rgb, so you are forced to tweak by feel instead of by Kelvin value. This promotes visceral interaction instead of technical interaction, which I believe attracts artists wich tend to work by feel more than by scientific technique.



PS. I want to make absolutely clear that I DO believe tonemapping should be reworked. I Know reworking tonemapping would help get better images, that is just the truth, my vote for most wanted feature is set to that and I'm sad we don't have it yet. Bokeh is actually one of the areas you would notice the change, as overblown highlights would look white in Fstorm and Solid Color in Corona, as it was discussed in my thread in 2018:
https://corona-renderer.com/forum/index.php?topic=22219.msg136777#msg136777

But the fact that so many people think that so much of Fstorm's realism is because of tonemapping, does not make sense. The fact that you estimate that Fstorm is more realistic 50% thanks to tonemapping is evidence of that.

We''ve had Ultra realistic renders for decades, even without all of the technologies we have today on materials, ray tracing and tonemapping. New tools just make it easier.

TLDR: I would like Corona to rework tonemapping to achieve what it is now IMPOSSIBLE to do in corona, but there is a lot they can do to make what is already possible much accessible. I think that would clear much of the misconception that Fstorm is so much better at "realism"

2020-05-02, 01:50:00
Reply #95

cjwidd

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I'm not sure it's a meaningful or empirical question to ask what percentage of an image is attributable to tonemapping - or shaders, lighting, modeling, etc.
« Last Edit: 2020-05-02, 03:45:06 by cjwidd »

2020-05-02, 03:42:37
Reply #96

agentdark45

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There is no way 50% of the realism coming from the Fstorm community is because of the tone mapping. Install Fstorm and try it. See if your images look 50% more realistic just like that. They won't.

But the fact that so many people think that so much of Fstorm's realism is because of tonemapping, does not make sense. The fact that you estimate that Fstorm is more realistic 50% thanks to tonemapping is evidence of that.

You yourself claimed you are not an experienced Fstorm user - I am a very experienced dual user of both Corona and Fstorm (along with other engines). As mentioned in my last post I exclusively use Fstorm for high end product vis. Why? Because due to testing both engines extensively on many scenes back and forth, some even with very basic materials, the result is always poorer in Corona (and no, this isn't down in part to DOF settings, material conversion or a lack of knowledge of non "out of the box" Corona settings). It is down to tonemapping and how highlights and blacks are handled by each engine. I have tried for days in some circumstances to match the image in Corona and the same ultra-photographic result simply was not possible within Corona's VFB no matter any combo of curve adjustments, contrast tweaking, HC tweaking, Kim Luts, various other LUTS, Dubcats settings e.t.c. I'm simply not willing to go "yeah that looks pretty close", which might suffice for some.

Again, look at your own example (attached). Highlights have been visibly ruined and the wood tones are off and not reacting correctly as they should IRL - an observation I went into in detail previously. The average viewer may not spot this but in detailed viewing it is clearly apparent. If you don't think this affects overall photorealism, or certain edge cases in visuals in any meaningful way (would you concede to some degree?) then I don't know what to say to you.

Why am I bringing up Fstorm? Because out of all of the render engines I've used it simply produces the most true-to-life images possible right now (and yes, it requires settings tweaking just like every other engine, so it's not a case of n00bish "hurr muh default settings" user error). The tonal balance of the image one is able to get out of Fstorm is always superior, and I'm no Fstorm fanboy either - I wouldn't use it if I didn't have to, I would love to use Corona for everything due to it's superior feature set.

If not for tonemapping, what else do you think contributes to Fstorms superior photorealism? I've already mentioned several times on the forums better bitmap filtering/sharpness, bump mapping implementation, colour handling, pleasing noise patterns, and better DOF speed/sampling - however most of these can be worked around within Corona, Tonemapping however cannot be as it stands. Hence my prior statement of 50% (which was a fast and loose approximation, not verbatim gospel) - put a highly experienced user of both engines to work on the same scene in both engines, work around the quirks of both Corona and Fstorm, and the Fstorm image will be more photographic and pleasing to look at, fact. Case in point: look at anything Bertrand Benoit has produced (who I think most would regard as one of the best in the game that uses many different rendering engines), and compare to his Fstorm renders, and this was with his first trial of the engine: https://bertrand-benoit.com/blog/westkaai-via-fstorm/ there is always something "off" about his photo realistic Corona and Vray renders (a minor uncanny valley effect, i.e lacking in brain fooling true photorealism).

Side note: Fstorm as a rendering engine in general is terrible in some real world use cases; interiors with a lot of bounced light where it's annoying portal system will not save you. And not to mention VRAM limitations. It's lack of material and plugin support is also shocking (still doesn't have proper composite maps and multi-layered materials) - another reason I don't use it for anything more complex than product vis.
« Last Edit: 2020-05-02, 04:30:53 by agentdark45 »
Vray who?

2020-05-02, 04:51:50
Reply #97

lolec

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Can you try to state what you think my point is? I think I've repeated myself and it's not working.

Do you think my point is:  Corona's tonemapping is fine, lets leave it like that ?  Because I've said the exact opposite.

Not sure what you are arguing with, so please state my point so I can continue the conversation with that as a starting point.

2020-05-02, 06:11:36
Reply #98

lolec

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Regarding that image of my earlier test, as others noted, I would have to use the exact same HDRI and closest as possible materials, not a simple conversion.

So I repeated the test. Same HDRI, Same LUT (KimAmlan02), Matched white balance. very simple materials.

Do you really see a 50% bump in realism in the Fstorm one? Maybe I don't have your eyes, it is entirely possible that I actually don't have the perceptual capacity.



Anyway, now that I've conducted the test in a more proper manner, my point stands. I will write it in bold so you don't miss it and you stop arguing with something I'm not saying:

Fstorm has better tonemapping.   I wish Corona had a DSLR like tonemapping

However, I don't think that is the main reason for the Fstorm community producing seemingly more realistic images more consistently than the corona render community.
I think there is a small number of users (Agentdark45 included) who have superior understanding and perceptual abilities and actually notice the super slight differences between the two renderers, which are real and measurable.

But I believe what MOST people notice is a vibrant community that attracts great artists who are learning faster and feeling comfortable sooner with Fstorm, and thus, becoming good enough that, overall, the Fstorm community is producing better renders, more artistic, more realistic.

Just to be super clear, FSTORM HAS BETTER TONEMAPPING, 100% agree. And it has a real impact in realism! I wish Corona implements this soon
ps. I also wish corona becomes a lot more beginner and artist friendly by making it MUCH EASIER to produce the best possible images it already can, which, BTW would inevitably be WORST than Fstorm regarding tonemapping. At least until corona implements a better tonemapping, which I will continue to push and wish for.

 

2020-05-02, 09:22:15
Reply #99

cjwidd

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I know Dubcat posted some F-storm LUTs a while back, what are you feelings about using those in Corona? I know it's already been said that no amount of LUTs can make up the difference, just curioous.

2020-05-02, 16:11:54
Reply #100

lupaz

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I think the whole discussion would be over if we had the option of taking a raw rendering from corona ,absolutely linearly, like a raw photo from a camera and do tests outside of Corona. It's my understanding that this is not possible currently. Is it?




EDIT: This is hilarious:
https://www.dpreview.com/forums/thread/4119248
Quote
Nothing scientific, but ince the early 2000's I've always felt the look of Canon RAW images had a more plastic-like look (that's not negative - just different) than Nikon images, which seems more realistic.
« Last Edit: 2020-05-02, 16:22:40 by lupaz »

2020-05-02, 16:27:46
Reply #101

Juraj

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I think the whole discussion would be over if we had the option of taking a raw rendering from corona ,absolutely linearly, like a raw photo from a camera and do tests outside of Corona. It's my understanding that this is not possible currently. Is it?

Did you mean F-Storm?

From Corona linear is easy, it's everything default (off & HC=1). Not sure how straight-forward it is from F-Storm.

That quote from DPReview.. photography "experts" are almost like homeopathy believers. "More depth", "More 3D", "Color science", etc.. are the most common nonsense they throw around constantly and discuss endlessly.

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2020-05-02, 16:31:45
Reply #102

lupaz

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I think the whole discussion would be over if we had the option of taking a raw rendering from corona ,absolutely linearly, like a raw photo from a camera and do tests outside of Corona. It's my understanding that this is not possible currently. Is it?

Did you mean F-Storm?

From Corona linear is easy, it's everything default (off & HC=1). Not sure how straight-forward it is from F-Storm.

No. I meant Corona.
So pixels collected to form the rendering are not filtered at all?
If this is the case, renderings taken from Corona to Photoshop would look just as realistic as fstorm. That doesn't happen.

2020-05-02, 16:48:14
Reply #103

Juraj

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I think the whole discussion would be over if we had the option of taking a raw rendering from corona ,absolutely linearly, like a raw photo from a camera and do tests outside of Corona. It's my understanding that this is not possible currently. Is it?

Did you mean F-Storm?

From Corona linear is easy, it's everything default (off & HC=1). Not sure how straight-forward it is from F-Storm.

No. I meant Corona.
So pixels collected to form the rendering are not filtered at all?
If this is the case, renderings taken from Corona to Photoshop would look just as realistic as fstorm. That doesn't happen.

Can you elaborate? I don't really follow.
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2020-05-02, 17:26:56
Reply #104

lupaz

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Sure.
Some are saying that what Corona needs is better tone mapping in order to get the same realism that you get from Fstorm.
Others are saying that the reason why Fstorm renderings feel more realistic is not tone mapping, but something else (to be determined).


Wouldn't it be a matter of taking a raw rendering from Corona and do the tone mapping in Photoshop?

This is what many of us do, and I feel that, even doing the tone mapping in photoshop, renderings from Corona don't look absolutely real, regardless of the scene, materials, and lighting. As someone said before in this thread, a photo looks real no matter the materials or lighting (unless you purposely try to make it appear not real).

So, again as someone said before, we are talking about 2 different things.

1- Tone mapping
2- realism.

To me to talk about tone mapping as the tool to make a rendering realistic doesn't make sense. And I think the confusion came from the beginning of this thread, when the OP wrote:

Quote
I'm either approaching lighting or tone mapping totally incorrectly; it is absolute guesswork every time, and rarely is it 'photorealistic'.

May be he didn't mean to use the word 'photrealistic'?

I do prefer to talk about making corona as realistic as possible, regardless tone mapping.