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Thread: Samplerinfo node and BRDF in mia.

  1. #1
    Join Date
    Jun 2009
    Posts
    10

    Default Samplerinfo node and BRDF in mia.

    Hi guys...

    Now I'm studying about shading..

    Recently I've downloaded a few shading from creativecrash site.

    And I watched a lots of shader is used by Samplerinfo node....So I looked it up a lots of site.

    But I recognized Samplerinfo node is same with BRDF in mia_matrial_x....

    is it right? or did I miss understand?

    If samplerinfo and BRDF are same, why many people use Samplerinfo node.....

    studying shading is really hard, plz help me...

  2. #2
    Join Date
    Dec 2005
    Location
    Chicago
    Posts
    2,389

    Default

    The sampler info node is not the same as BRDF in the mia_material.

    But the effects of the facing ratio elements can be similar.

    The sampler info node can return different data based on what you are looking at. This can be normals, world position, facing ratio, etc. In many cases this is used as an extra node for compositing where you way want to use this data to do certain tricks in post using normals, world points (slice), etc in 2D from an image created with an element of the sampler info piped to a surface shader.

    You can indeed use a ramp and facing ratio plugged into reflection to simulate the BRDF effect. And before the mia_material it was often used to create that kind of falloff in the render.

    The mia_material also uses the BRDF to control how that reflection is weighted along with other effects like diffuse reflection, refraction, etc and maintains a physical balance based on those weights. Facing ratio alone won't give you that physical conservation.

    In more complex terms, BRDF applies to more than just a simple facing ratio and supplies you with surface reflection (diffuse and otherwise) from real materials that have been measured from multiple angles to capture this effect and simulated in the render as a real world material.
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  3. #3
    Join Date
    Jun 2009
    Posts
    10

    Default

    Oh every time really thank you. Remydrh

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