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Tutorial: Absorption in Cycles using the Raylength-Node



Create more realistic transparent materials in Cycles with this videotutorial by BlenderDiplom.

Gottfried Hofmann writes:

Have you ever wondered how those crazy node-groups for faking absorption with the new ray-length-node are working? This tutorial shows you how the trick is done from the very basic of how Cycles is treating light and transparency to the fully-fledged node-group for re-use in your own projects. You will also learn how to translate a physical formula into Cycles nodes.
This is probably my most didactic tutorial ever.



    • I hope one day caustics in Cycles will be based on Photon Map or a similar feature. Right now it's almost unusable (sigh...).

  1. Very handy tutorial!
    Thank you, Gottfried! It's very wide explanation! I don't like to work with formulae but seems it's not so scary :)

  2. You may like to try modifying each colour (wavelength) separately for more realistic results. Since there's an exponential function in there, it's not a linear relationship that you can just multiply though, so using a single absorption value to blend between colours doesn't fully capture it all.

    See here:

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