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Thread: Lighting without Light

  1. #1
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    Lighting without Light

    Nothing revolutionary,
    a basic teapot from Modeler, a NULL as Light reference,
    used with Spot to build a direction for normal in
    Occlusion node in DP_Kit (or directly used as Target
    with Directional option in SG_AmbOcclusion),
    direction is coupled with Spot Smoothed Normal
    to build a basic Lambert Diffuse Model,
    A small Angle of 10° in Occlusion node gives
    nice soft shadows.

    Click image for larger version. 

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    Thanks to Simon Lundberg for scene and first input.
    Denis.

  2. #2
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    You could use Pom's Ambient Occlusion node too,
    it has not normal input, but DP_Kit has a Replace Spot node
    in Processing tab, to replace positions and normal,

    Click image for larger version. 

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    Denis.

  3. #3
    Valiant NewTeKnight Matt's Avatar
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    Am I reading this right? You are controlling the direction of the ambient occlusion by linking it to a NULLs position?
    UI / UX Designer @ NewTek
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  4. #4
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    ...With the substraction of the Spot world position
    to give a pseudo light direction, this is for replacing
    the normal of Spot to orient the Occlusion cone/hemisphere.

    Denis.

  5. #5
    Super Member Captain Obvious's Avatar
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    Yep, that's right. This is a technique I've been experimenting with when I realized that GI was too slow for an animation we're working on. I will post more information and maybe a tutorial when I've done more work on it.
    Are my spline guides showing?

  6. #6
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    In fact, amb occlusion is not convincing to fake
    entirely lighting on the teapot, even with SubD mesh.

    Since raytracing hit real polys, self (occluded) shadows
    reveal flat/unsmoothed geometry, when the light direction
    becomes tangential to the polygon,
    that's why a Diffuse Model is important to cover
    the areas of the mesh, which are opposite to the pseudo light.

    Note that a bit higher "Shift" is helping a lot to
    avoid unsmoothed polys.

    Denis.

  7. #7
    Xsi has this feature. Captain, High mes and directional occlusion is a great idea. I just watched some training for xsi that used that technique with great results...

  8. #8
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    Here, the teapot has med/low res, no SubD,
    without Diffusion Shading you get this:

    Click image for larger version. 

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    Denis.

  9. #9
    To add to that... for an interior you will need to use a distance to gradient to fade from directional to nondirectional for good results...

  10. #10
    \\ is sparkling // Iain's Avatar
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    Quote Originally Posted by Captain Obvious
    Yep, that's right. This is a technique I've been experimenting with when I realized that GI was too slow for an animation we're working on. I will post more information and maybe a tutorial when I've done more work on it.
    Can we see any of your results in a production scenario?
    portfolio

    The Liver is evil and must be punished!

  11. #11
    Super Member Captain Obvious's Avatar
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    Quote Originally Posted by Iain
    Can we see any of your results in a production scenario?
    Not yet, no. Once it's in the public, I will show you whatever I can.
    Are my spline guides showing?

  12. #12
    Super Member Captain Obvious's Avatar
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    Quote Originally Posted by dpont
    You could use Pom's Ambient Occlusion node too,
    it has not normal input, but DP_Kit has a Replace Spot node
    in Processing tab, to replace positions and normal,

    Click image for larger version. 

Name:	ReplaceNormal.gif 
Views:	401 
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ID:	53095

    Denis.
    What does the Replace Spot node actually do?
    Are my spline guides showing?

  13. #13
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    Replace Spot node let you replace a few
    Spot input like smoothed normal or world position,
    in case you replace them directly in the input
    of the node, i.e: LW Occlusion node hasn't not
    normal input.
    Replace Spot node must be set after the node
    or node chain you want modify.

    Denis.

  14. #14
    Super Member Captain Obvious's Avatar
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    Ahh, that makes sense.
    Are my spline guides showing?

  15. #15
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    Edit:...Was too fast with my typos:

    "in case you (can't) replace them directly in the input
    of the node..."

    Denis.

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