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Albedo charts for PBR?

Discussion in 'Unity 5 Pre-order Beta' started by the_motionblur, Oct 28, 2014.

  1. the_motionblur

    the_motionblur

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    Since the standard shader for Unity 5 is based on specular/roughness and I keep reading that it's important to use correct values I was wondering... Most people detailing how to use the workflow keep saing that albedo and rougness values with this method are super important and should be derived from lists or charts that can be found on the internet.

    Where are those charts?
    If I find a chart for IORs how do I derive a specular value from it?
    Renaldas Zioma from Unity says it's easy to derive but I don't really see how it can be derived easily by his examples alone.

    While everybody keeps talking about those charts and best practises keeping the values grounded in reality I really would love to know where I can get this from without having to mess with polarized light and photography.

    Does anybody here have any experience to share?

    (edit) Damnit - the title is sort of misleading. Albedo charts is the wrong terminology. I hit 'post thread' too soon. Sorry. 'PBR value charts for materials' would probably be more correct.
     
    the_motionblur, Oct 28, 2014
    #1
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  2. peteorstrike

    peteorstrike

    Unity Technologies

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    Hello!

    Sebastien Lagarde's charts for Dontnod are good for setting the specular and smoothness values. You can find a page and link to download the full-res png of the charts here - http://seblagarde.wordpress.com/2012/04/30/dontnod-specular-and-glossiness-chart/

    Another good resource for now is Substance Painter - it has a great 'Unity 5' export option, so it can be really helpful to paint onto a sphere with their preset materials, export out and load up the resulting maps in the Standard Shader. This way you can see values for the albedo as well as the Spec/Gloss.

    We'll have a set of preset materials, amongst other useful PBR-related things, available before launch which should hopefully help people see how the maps and colour values can be set for different results, but hopefully these will help you out for now.
     
    peteorstrike, Oct 28, 2014
    #2
    jashan, DanielVanches and the_motionblur like this.

  3. the_motionblur

    the_motionblur

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    Hey - thanks a lot @peteorstrike . :)

    Do you have a guideline ready somewhere what channels the standard shader expects in the bitmaps fed into it?
    So far it seems albedo is just RGB while specular uses RGB for reflection color and alpha for roughness, correct?
     
    the_motionblur, Oct 28, 2014
    #3

  4. peteorstrike

    peteorstrike

    Unity Technologies

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    There should be some info in your offline user manual about which maps are expected for each slot. If you go to the Help menu and open the user manual you should find some info under:
    Unity Manual > Graphics > Graphics Overview > Shaders > Standard Shader > Standard Shader Procedures

    You can also try opening the following link in your browser, switching in your Unity install directory path:

    file:///YOUR_INSTALL_PATH_HERE/Editor/Data/Documentation/html/en/Manual/shader-UniversalShaderProcedures.html

    Give me a yell if that's missing or you're on a mac (I'll have to go dig up where it hides there)!
     
    peteorstrike, Oct 28, 2014
    #4

  5. the_motionblur

    the_motionblur

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    Got it. Thanks :)
     
    the_motionblur, Oct 28, 2014
    #5
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  6. ReJ

    ReJ

    Unity Technologies

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    Smoothness / roughness values are pretty much an "artistic decision" in the engines/tools. Physical values of roughness are not really handy for authoring (visual results you get are very non-linear with respect to the values). Instead we remap physical roughness values to something more straightforward for artists. Unfortunately there is no universal agreement on exact details of such remapping yet.

    Which is why tools like Quixel's dDo has different export profiles for different engines. And if you are creating your textures by hand - you have to pretty much eyeball the results. If you have your favorite texturing tool with preview or preview tool you're using - please, tell us. We will consider, if we can mimic it. Currently we're leaning towards following Marmoset Toolbag2 exactly.

    That said we should have visual examples in our documentation. Dully noted. Will be done.

    Albedo and Specular colors on the over hand come from measuring real materials and are universal across the engines.
    There are a number of good charts:
    1. http://seblagarde.wordpress.com/2012/04/30/dontnod-specular-and-glossiness-chart/
    2. http://www.marmoset.co/wp-content/uploads/materialref02.png from http://www.marmoset.co/toolbag/learn/pbr-practice
    3. Slides 55-64, specular values: http://blog.selfshadow.com/publicat...rse/hoffman/s2014_pbs_physics_math_slides.pdf
     
    ReJ, Nov 5, 2014
    #6
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  7. the_motionblur

    the_motionblur

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    Hey - thanks a lot for asking :)

    From my perspective: please aim for syncing to Allegorithmic's Substance Designer and Painter as well if not even foremost.
    Toolbag 2 is very cool and a good thing to support for people who want to use their art in the same way for Marmoset promo shots as well as Unity without tweaking any further. I think it's also a good thing to sync to Toolbag for freelancers doing groundwork without a Unity license at their hands. After all - coming from Quixel or Designer and having a good result in Marmoset means it would look good in Unity.

    That said: I think Marmoset and Substance Designer aren't even that far off from each other. Though, for everybody designing textures directly inside Substance Designer it would still be a huge benefit to have a mostly seamless transistion without the added Marmoset step inbetween (for example I usually use Unity for promo shots instead of Marmoset since I already have a Pro License and it feels logical to me). Especially with exporting directly/automatically from within Designer to Unity I find the transition to the final output to be a little more relevant than to Marmoset.

    Here's an additional thread with a few early observations regarding Substance workflow:
    http://forum.unity3d.com/threads/weird-pbr-results.276989/
     
    the_motionblur, Nov 5, 2014
    #7

  8. Devil_Inside

    Devil_Inside

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    I noticed that Marmoset Toolbag is now some kind of standard tool to showcase models in the cg artists community, so I think UT should aim for Marmoset Toolbag, and all the authoring tools should aim for Marmoset Toolbag.
     
    Devil_Inside, Nov 5, 2014
    #8

  9. Deleted User

    Deleted User

    Guest

    Hi,
    As ReJ mentioned, you don't need to utilize measured values for smoothness. The smoothness map is the most artistic map you can author in PBR. There really isn't a wrong answer with smoothness. Here I am saying "smoothness" as this is what it is referred to in Unity. However, this map really defines the micro-surface details and is the same as roughness(metal/rough workflows) or glossiness(spec/gloss workfow). I like to say that the micro-surface map is king. This is the map that truly gives the surface character and tells the story of where the surface has been, what its environment is like and what it has been in contact with.

    With Substance, we do not preform any remapping with our shaders. Each engine often has its own remapping and there isn't a standard to adopt. With Substance Painter and Substance Designer, you have the ability to add a custom shader to match to a specific engine. We supply PBR shaders for Metal/Rough and Spec/Gloss workflows and the Specular/Gloss shader works very well with Unity 5. With Substance Designer, you also have the ability to load a custom tangent basis for computing normal maps. We ship with the same tangent basis as Unity so that you have a synced workflow between Substance and Unity with normal maps.

    We may also add an export profile option in the future for specific remapping of outputs. However, this can be done now with custom substance materials. Substance Designer can be used to author custom nodes utilized by substances and outputs can easily be set to be remapped with user controls for specific engines such as Unity. The very nature of Substance is to be adaptable and customizable and with native Substance Material integration in Unity, you get a much more powerful PBR toolset than what is capable with a Photoshop driven solution.

    Cheers,

    Wes
     
    Deleted User, Nov 12, 2014
    #9