I'm trying to replicate the "polarisation" effect - so if you look through a piece of glass that's polarised you can see an image behind that image that normally would be invisible or white as it's been polarised too. So, I want to have a see-through material I can apply to something, so that the thing behind it is only visible if seen through that material. Is that possible? If so, how?

  • $\begingroup$ Will the material possibly be "seen" through other transparent objects you don't want to reveal it? If not, you can test if the Transparent Depth value > 0. $\endgroup$
    – PGmath
    Sep 20, 2016 at 17:01
  • $\begingroup$ No, it will be seen through all transparent objects! Can you explain a bit more about testing the Transparent Depth value > 0 ? Where do I do that and how? $\endgroup$ Sep 20, 2016 at 20:39
  • $\begingroup$ You need render layers. $\endgroup$
    – Bradman175
    Sep 21, 2016 at 0:42
  • $\begingroup$ @alberto2000 what ShadyPuck answered basically. $\endgroup$
    – PGmath
    Sep 21, 2016 at 3:34

1 Answer 1



enter image description here

Material seen through window:

enter image description here

Viewport render showing Suzanne through window:

enter image description here

Viewport render showing invisible Suzanne next to window:

enter image description here

What I have is a Glass BSDF window, slightly off white in color so to be seen, and with a 1.00 IOR to be in all rights except one a Transparent BSDF. Glass BSDFs refract rays like glass refracts light, and I can test for that refraction (called a Transmission Ray).

My Suzanne has a material (red Diffuse BSDF, but can be anything) that is mixed with a pure white (clear) Transparent BSDF. The mix Fac:, whaddoyouno, just happens to be a Transmission Ray :)

.blend file:

  • $\begingroup$ @alberto2000 Glad to help! $\endgroup$
    – Shady Puck
    Sep 21, 2016 at 20:01

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