Author Topic: PBR tuning of the reflectivity ability  (Read 21668 times)


2014-09-21, 21:44:09
Reply #31

Juraj

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Excellent compilation, I love Polycount.com, def my favorite forum
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2014-09-23, 08:09:49
Reply #32

vicnaum

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I don't understand something about GGX....

I used to think that GGX is a microfacet/microsurface model. So all these things should come with it:
1) More realistic blurry highlights with halos around bright things.
2) Reflections become less gloss and more sharp at 0deg angles, and the amount of this is controlled by microsurface parameters (width/height).
3) Reflection brightness dimming is controlled by these parameters too.

Only the 1st point with blurry highlights is now implemented in corona daily build.
Will Ondra continue developing the other points 2 & 3?

Here are some interesting materials with explanations about it:
http://www.cs.cornell.edu/Courses/cs6630/2012sp/slides/05ufacet.pdf
<-- great vid with beautiful real-world explanations & examples.


2014-11-01, 14:01:22
Reply #34

Stanislav_But

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Hi again
We tested coronamat long time to find workflow that would be maximum close to phisics.
And we found that any changing of ReflLevel or ReflRGB below from of 1 or 255rgb shifts the whole fresnel curve in Y-axis down - in other words this changing cuts reflection.
In same time changing of the IORreflect up/down change only start point of fresnel curve in Y-axis up/down and save 100% reflection with 0 deg - as it must be.

Second moment we found - the glossiness of material from point of view. When POV moves down close to 0 deg then the reflection will change from blured reflection to sharpness reflection more and more untill will 100%. Exception - super matte materials

In attach the same information in pictures

2014-11-01, 20:45:32
Reply #35

vicnaum

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Exactly.

So, we're left with three parameters for an ordinary material:
1) Diffuse (albedo) color/map
2) IOR
3) Glossiness/Roughness color or map
(optional, for metals: Reflection color)

Everything else is redundant and is deducted from those.

Soon we'll reveal the workflow with new PBR materials compared to photographic tests.

2014-11-01, 21:13:34
Reply #36

Stanislav_But

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Interesting
Now I found that in there Refractiveindex.info is Reflection calculator. And for example for plastic we see this:
http://refractiveindex.info/?shelf=other&book=CR-39&page=poly
IOR - n = 1.4980
Refl - R = 0.039744
Even Refractiveindex.info agrees that need to use true physics categories (;

2014-12-11, 19:08:31
Reply #37

Ondra

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This is no longer a feature request, but a discussion, so I moved the thread. We will consider some alterantive material approaches in the future.
Rendering is magic.
Private scene uploader | How to get minidumps for crashed/frozen 3ds Max | Sorry for short replies, brief responses = more time to develop Corona ;)

2014-12-11, 21:40:51
Reply #38

Captain Obvious

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I've been using GGX and GRT lately, and I really like both.

2014-12-13, 01:00:44
Reply #39

marioteodoru

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I'm sorry to jump in, i have an somehow unrelated question, and please bear in mind i am very nontechnical. I still haven't understand completely how corona settings works for materials.
So, should i understand that i can input values like 0.0234 or with even more decimal ? I'm asking because i'm just a user, so for me , in my head it was working more like 0.1- 0.2-0.3 up to 1.  It this high precision for all the settings in materials or just for Refl?  Please excuse me if my question is stupid, but reading this thread, i can see that i   actually have no idea how to make accurate settings for materials. Maybe also the reason for my poor materials.  Is this also for diffuse? I could use  a value of 0.17263 and make sens ?

2014-12-13, 05:32:49
Reply #40

Juraj

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I'm sorry to jump in, i have an somehow unrelated question, and please bear in mind i am very nontechnical. I still haven't understand completely how corona settings works for materials.
So, should i understand that i can input values like 0.0234 or with even more decimal ? I'm asking because i'm just a user, so for me , in my head it was working more like 0.1- 0.2-0.3 up to 1.  It this high precision for all the settings in materials or just for Refl?  Please excuse me if my question is stupid, but reading this thread, i can see that i   actually have no idea how to make accurate settings for materials. Maybe also the reason for my poor materials.  Is this also for diffuse? I could use  a value of 0.17263 and make sens ?

If none of this makes sense, don't complicate your life. Some of the articles linked in this thread explain all that's discussed, don't ask for tl:dr notes.

But matter of fact, no, none of it is important, you don't need to use any numbers and absolutely not such small minimal decimals.

Here is simple (/simplified) guide to live by:

Non-metal: Keep everything default (Ior: 1.52) and create textures that suite your look. Some materials can be more reflective (up to 2+) like plastics), some are less (1.333 like water), but you can still keep it default.
Metal: Keep Ior between 4-to-40 +/- (the simplest way without using curves or anything to setup exact specular curve of metal).

Adjust Glossiness using 0-to-1 and textures how it looks good to your eye.

That's all the number you need in nutshell. You don,t need any 0.2122475 magic to make something look real, you missunderstood this thread.
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2014-12-14, 13:31:45
Reply #41

marioteodoru

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Thank you Juraj_Talcik for your explanation.  :)

2014-12-25, 22:26:18
Reply #42

CiroC

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I'm sorry to jump in, i have an somehow unrelated question, and please bear in mind i am very nontechnical. I still haven't understand completely how corona settings works for materials.
So, should i understand that i can input values like 0.0234 or with even more decimal ? I'm asking because i'm just a user, so for me , in my head it was working more like 0.1- 0.2-0.3 up to 1.  It this high precision for all the settings in materials or just for Refl?  Please excuse me if my question is stupid, but reading this thread, i can see that i   actually have no idea how to make accurate settings for materials. Maybe also the reason for my poor materials.  Is this also for diffuse? I could use  a value of 0.17263 and make sens ?

If none of this makes sense, don't complicate your life. Some of the articles linked in this thread explain all that's discussed, don't ask for tl:dr notes.

But matter of fact, no, none of it is important, you don't need to use any numbers and absolutely not such small minimal decimals.

Here is simple (/simplified) guide to live by:

Non-metal: Keep everything default (Ior: 1.52) and create textures that suite your look. Some materials can be more reflective (up to 2+) like plastics), some are less (1.333 like water), but you can still keep it default.
Metal: Keep Ior between 4-to-40 +/- (the simplest way without using curves or anything to setup exact specular curve of metal).

Adjust Glossiness using 0-to-1 and textures how it looks good to your eye.

That's all the number you need in nutshell. You don,t need any 0.2122475 magic to make something look real, you missunderstood this thread.

But, when you tweak the materials, do you use the Material Editor preview?

2014-12-26, 00:18:34
Reply #43

Stanislav_But

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2014-12-26, 09:04:43
Reply #44

CiroC

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But, when you tweak the materials, do you use the Material Editor preview?

of course
Why do you ask?

Well, I am kind of new Corona's user and I usually tweak the materials based on the render I am getting. But if the preview from the Material Editor is accurate that means that after creating a material I only need to tweak the material do look good in the render?

I may be crucified for saying this, but I never relied on the Material's preview to create the material and adjust the maps.