Refraction in Photoshop 3D

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3D designer Stephen Burns shares this tutorial on adjusting for light refraction when 3D modeling things like water and glass in Photoshop Extended.


  • Just to clarify for those who don’t feel like reading up on Wikipedia, refractive index is a “boundary” condition, so the light changes angle on each boundary crossing. For rendering, that means your model needs some kind of depth to it – two sides to the glass vase, for example. In this case it also means you have to allow transparency in your model since PS doesn’t do subsurface scattering on thin layers (like a layer of oil sitting on top of a smooth surface).

    What’s going on is the light is bent ever so slightly when it hits a boundary and keeps going. This is different than internal reflection, like with a prism. So, the light hits the outside of the vase, gets bent a little, hits the other side of the vase, and gets bent back the other way. If the entry and exit surfaces are exactly parallel, then the light ray coming out will be parallel to the light ray going in. With this vase, the surfaces are curved, so you get the distortion Stephen talks about – the rays are no longer parallel.

    It may not be obvious, but this is a pretty powerful feature in Photoshop’s rendering capability. There’s a lot of math going on in the ray tracer. Use the power wisely!

  • Hilander says:

    Hi, thank you very much,
    it is an essantiel tutorial,
    thank you !