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Shadow catchers for Iray HDRI

fastbike1fastbike1 Posts: 4,078
in Technical Help (nuts n bolts)

Need a little help. I understand what shadow catchers are for when rendering with a an environmental map and Draw Dome ON. What I don't know is how to make/use/find said shadowcatchers.

Thanks in advance.

Comments

  • ToborTobor Posts: 2,300

    If you mean a virtual surface that allows shadows to fall on it, the ground is a unique element that "catches" a shadow even though it has no geometry. This is built into Iray's environment dome. There are no equivalents for other virtual structures, like walls, however. You have to put geometry there to "catch" the shadow.

    If you mean "catching" a shadow and swollowing it so it doesn't show, that's supported in Iray Interactive (Render panel, Render Mode). When this mode is active, you can select objects in the scene and set their Display/Casts Shadows. You can also control shadows in the Render panel under Shadows and Lighting. In this mode, Iray also supports a "receives shadows" on/off feature, but I don't see it implemented in D|S, or if it is, it's non-obvious.

  • prixatprixat Posts: 1,588

    It certainly is 'non-obvious'! laugh

    The nearest thing to the shadowcatcher you know from 3delight is the Iray "Matte" material.

    That's built in to the Iray shader but the nodes have to be switched witha script. Find the script via the Content Library.
    (step 5a is optional, right-click to get the submenu and click 'create custom action'. It creates the Scripts (5b) menu and adds the script as a menu item) 

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  • prixatprixat Posts: 1,588

    Then look at the 'Parameters' tab (NOT the Surfaces)

    ...you will have a couple of extra parameters including the 'Matte' node.

     

    matte0.jpg
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  • prixatprixat Posts: 1,588

    Iray Matte is a bit more than just a shadow catcher. it will also 'catch' highlights and colour bleed.

     

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  • ToborTobor Posts: 2,300

    EGG-celent. prixat! I had forgotten about the discussion here about the matte setting. Though not quite the same as the the "receives shadows" boolean, it looks like it might get the job done until D|S supports the real deal (we'll know it, because like Cast Shadows, Receives Shadows it will only work in Interactive mode, per the Iray programmer's documentation).

     

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