Author Topic: PBR kinda materials  (Read 71738 times)

2014-06-03, 09:09:39

vicnaum

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What do you guys think of taking principles of PBR somewhere in future to develop materials in corona?

http://www.marmoset.co/toolbag/learn/pbr-theory
http://www.marmoset.co/toolbag/learn/pbr-practice

Key aspects (for ones who are lazy to read):
1) Diffusion & Reflection linked: More leflection -> Less diffusion
2) Fresnel linked to base reflectivity & gloss
3) Microsurface roughness linked to Reflection
4) Diffusion, Translucency, SSS all linked as representing the same effect
...etc...

That leads us to much simpler system, wich much less parameters, where less errors can be made.

I bet in a couple of years all renders will shift to something like that (comparing how they shifted from simple phong Diffuse/Specular Highlights model 10-15 years ago - to what we have now in vray/corona/etc).

So why don't make that shift earlier?

Btw, the described system can be tried out here (in realtime): http://www.marmoset.co/toolbag/store

2014-06-03, 09:37:50
Reply #1

Captain Obvious

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Corona's material is already energy conserving, albeit in an incorrect fashion (clamping rather than scaling). Not sure exactly what you feel is missing.

2014-06-03, 09:46:44
Reply #2

maru

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In my opinion all these physically-accurate restrictions should be respected by skilled artists but they should also be allowed to break them.
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2014-06-03, 10:17:56
Reply #3

vicnaum

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In my opinion all these physically-accurate restrictions should be respected by skilled artists but they should also be allowed to break them.

Well, skilled artists use canvas & brushes and are free to do whatever expressionism they want ;)
My opinion is that the renderer should help artist to achieve phys.correctness, without knowing all the rocket-science connections laying under the numerous variables.

Treat it like dynamic physics simulation instead of manual keyframing. And, btw, they don't exclude each other - manual tweaking is still allowed if artist needs.

2014-06-03, 11:01:33
Reply #4

Tanakov

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Well for me Corona materials are already using this kind of knowledge.

M/b im missing something, but adding information where setting something above limit of realism highlights the material in some way would be nice, but setting the limit and restrictions would hurt the creative process of special effects.
Using Corona since 2014-01-02
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2014-06-03, 15:50:40
Reply #5

maru

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In my opinion all these physically-accurate restrictions should be respected by skilled artists but they should also be allowed to break them.

Well, skilled artists use canvas & brushes and are free to do whatever expressionism they want ;)
My opinion is that the renderer should help artist to achieve phys.correctness, without knowing all the rocket-science connections laying under the numerous variables.

Treat it like dynamic physics simulation instead of manual keyframing. And, btw, they don't exclude each other - manual tweaking is still allowed if artist needs.
Well, skilled artists use canvas & brushes and are free to do whatever expressionism they want ;)
Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us

2014-06-03, 16:16:21
Reply #6

romullus

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When i shifted from mental ray to corona, i was shocked how much simpler CoronaMtl is compared to  A&D material. It almost felt like handicapped and it took a while for me to get used to it. And now you want it to be even more simple!? :]
I'm not Corona Team member. Everything i say, is my personal opinion only.
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2014-06-03, 16:20:48
Reply #7

Juraj

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YES

YES and YES !

Real-time engine nowadays (Unreal 4, CryEngine 3.6.4 EEAS, I use both at the moment) have so much better material system than offline rendering has, that offline rendering looks like prehistoric legacy almost :-).
(with exception of VFX houses of course, both ILM, MPC and all the big boys already using this new model).

I already asked Keymaster if he's willing to implement advanced BRDF models (like GGX, ABC or ShiftedGammaDistribution, currently all as plugins by Sergey Schliaev, although GGX is already integrated in Vray3.0).
I understand he has little time and there might be more important things (not to me heh), but imho it's much better to differentiate from others than slowly add features that all others already have. I don't want a better clone, I want revolutionary product instead if I could choose.


Btw Maru, the shaders still respect any sort of look, even completely stylized or unrealistic, they just make the creation of it vastly easier, and more natural. At the moment, it's absolutely odd eye-balling, where I dare to say, 90perc.
of users do not even no what value should actually be in reflection slot or how to even create TRUE metallic shaders. Quite frankly, all metals and plastics out there look like shit to me.
Did you even look at those shaders ? It's not harder, it's not scientific. It's logical and superb.
IMHO it's definitely a time for revolution, I don't understand this harkening to original concepts and still using the same material as Scanline. It bothers me so much than I contemplate just sticking with real-time by end of this year. To
me it's already evolved enough and it's evolving by master space speed.

Did you guys read the original post ? Did atleast 5 minute of research ? Every single post seems somehow off-mark to me.

Well for me Corona materials are already using this kind of knowledge.
Not really...not in any way Vic outlined.

but setting the limit and restrictions would hurt the creative process of special effects.
There are no limits or restrictions. How did you guys translate it into this conclusion ?

Well, skilled artists use canvas & brushes and are free to do whatever expressionism they want ;)

And it's working amazingly for everyone.. I hoped the "it's the artist, not the toolz" days are long gone.
We could have just stayed with Scanline.

My idea would be like a separate, experimental shader to use alongside.

« Last Edit: 2014-06-04, 01:05:53 by Juraj_Talcik »
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2014-06-03, 17:06:37
Reply #8

Captain Obvious

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So it's just about having more choice for the specular reflection model? Because that is literally the only difference between the new GGX (etc) materials and Corona's material.

2014-06-03, 17:07:32
Reply #9

Juraj

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So it's just about having more choice for the specular reflection model? Because that is literally the only difference between the new GGX (etc) materials and Corona's material.

No, that's like 1/10 of it...but it's the easiest feature to implement. Already does a big difference to me.

Maybe Vic's original post seemed confusing because he linked PBR very closely to real-time (Marmoset), where is greatly integrated but it's not really tied to it in anyway.

This is my favourite article on it which I keep returning to, maybe that better describes it ?

http://disney-animation.s3.amazonaws.com/library/s2012_pbs_disney_brdf_notes_v2.pdf
« Last Edit: 2014-06-03, 17:12:09 by Juraj_Talcik »
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2014-06-03, 17:29:33
Reply #10

Captain Obvious

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The Disney implementation is pretty cool; I'd love to see something like that in Corona. But most of the "omg pbr!" features are actually already in Corona, and have been from the start.

2014-06-03, 17:31:13
Reply #11

lacilaci

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In my opinion all these physically-accurate restrictions should be respected by skilled artists but they should also be allowed to break them.

Well.. IMHO physically-accurate restrictions should be respected by "physically-accurate" renderer by design. If for no other reason then for error prevention at both user level and rendering execution as well.. i think... :D

2014-06-03, 17:34:33
Reply #12

Juraj

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The Disney implementation is pretty cool; I'd love to see something like that in Corona. But most of the "omg pbr!" features are actually already in Corona, and have been from the start.

Of course. The PBR is revolution for real-time, because previously, there was no physical correctness at all. But the benefits are still here even for classic off-line renderers.
Have you ever seen Maxwell ? It's clumsy and odd, but it comes really closest, with controls for 0 and 90 angle incidence, roughness affecting both diffuse and specular reflectivity,
natural layering,etc..

To me it's way more natural once you dive into it, and soon there will be a lot of available data for it (measured values for everything, prepared textures,etc..) because real-time PBR market is so much bigger than
visualization market (which quite frankly, will be the only market for Corona), that it would make future life much easier for everyone.

It would also allow for easy translation of scenes to real-time, something that will happen a lot soon. 80perc. is just different controls, so that's why alternative shader is imho viable option. And the rest 20perc. allows
for easier and more precise shaders for specific materials (mostly metals).
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2014-06-03, 17:37:46
Reply #13

rampally

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Juraj_Talcik you are 100% correct I HOPE GGX shader will be there in future corona ....!!!
now i am doing same like ggx   in corona with the help of three shader its really hell pain ...KM PLEASE HELP US

2014-06-03, 19:50:12
Reply #14

Polymax

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I think it was a good direction in the development of Corona renderer.
Here's a visual comparison:
http://www.shlyaev.com/rnd/37-cpp-category/54-ggx
Corona - the best rendering solution!