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Refraction tweaks with iray

Posted by on 25.03.2014 in iray
iray_matte_tip_renders

When you’re working with refractive glass and a matte/environment/background in iray you may run into a problem if you’re using solid (refractive) glass.  The problem is the glass refracts the “invisible” matte ground plane as illustrated in this first render:
iray_refract_000
You can avoid this by using a thin-walled glass instead of a refractive glass.  However, that’s not always practical as you may need the refraction for a solid object, etc..
iray_refract_001

One thing I’ve been doing is placing a matte refraction object behind the solid glass object.  Here’s a screen shot of the scene with the matte refraction object added:

iray_matte_tip_002

I then assign a thin-walled glass preset to this refraction geometry (pink wireframe object).  Then assign the geometry to the “Matte Objects” section in the iray Matte Environment shader.  Screen shot:
iray matte

The result:
iray_refract_002

Of course this becomes a bit more complicated if you’re rendering an animation.  You could link the refraction geometry to the camera or perhaps use another method to prevent the matte/ground refraction issue.