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Ferdin Joe avatar image
Ferdin Joe asked ·

How to get out a refraction matte with aistandardsurface

Lets assume that there are 2 eye balls, inner eye(pupil+iris texture) and outer eye (transparent with IOR 1.45). I need to take out RGB matte for the eyes of characters to enhance them at comp. since the final beauty render has refracted eye the eye would be slightly magnified because of tranmission. Is there a work around for this ?

transmissionrefraction
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Nicolas Miebach avatar image
Nicolas Miebach answered ·
@Ferdin Joe

That is a good question! I´m looking for an option to render out distortion maps as well. Making own Tech Shaders and Render Layers is time consuming and passes which are needed all the time should have there dedicated AOVs.. maybe a feature request? Did you got a solution?

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Ferdin Joe avatar image
Ferdin Joe answered ·
Thanks @Robert, "assigning RGB shaders to your inner eye parts and rendering it WITH cornea distortion" - this is the work around which i am already doing. was just wondering if there is a way to render the matte in a separate AOV or something like that so that i don't have to render the scene again. 
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I have not worked much with Arnold Core 5.X yet and the AOVs seem to act weird here on my PC. If it's anything other than a surface shader plugged into a aiWriteColor node I can't get it to render. Standard shader is always pure white in that AOV, does not matter what settings I choose. But I believe that's a topic for another question.

But maybe it works for you: Create a custom AOV and in the shading groups of your desired matte objects plug in the matte shaders in the "Other AOVs" slot. And in the eye cornea the non-spec distortion shader. That should in theory work. Could not test it ;(

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Robert Mastny avatar image
Robert Mastny answered ·

Transmission distortion with higher than 1 IOR values are expected and wanted, aren't they?

So if you would create a matte for iris, pupil and sclera without the transmission distortion it would not fit your final beauty render.

Only working scenario I see is assigning RGB shaders to your inner eye parts and rendering it WITH cornea distortion but of course disabled reflections and specular on that shader, just transmission / distortion.

You can then use these distorted RGB images in your compositing software to grade all parts from your eye beauty render and the matte would fit.

I hope this answers your question!

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