Dispersion Changes IOR?

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treddie
Licensed Customer
Posts: 739
Joined: Fri Mar 23, 2012 5:44 am

Hi.

Attached is a video showing what appears to be a refraction difference between specular w/ and w/o dispersion. My understanding was that dispersion does not change the "center" refraction angle, but only disperses the wavelength-dependent refraction angles ABOUT that center. Therefore, should not the overall depth of the image behind the glass appear exactly the same w/ and w/o dispersion?
Dispersion Changes IOR.mp4
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Win7 | Geforce TitanX w/ 12Gb | Geforce GTX-560 w/ 2Gb | 6-Core 3.5GHz | 32Gb | Cinema4D w RipTide Importer and OctaneExporter Plugs.
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roeland
OctaneRender Team
Posts: 1823
Joined: Wed Mar 09, 2011 10:09 pm

Octane uses Cauchy's equation for dispersion. The index input becomes the B parameter, and the Dispersion Coefficient is the C parameter. The average index of refraction becomes a bit larger than the index setting.

Wikipedia article here: http://en.wikipedia.org/wiki/Cauchy%27s_equation

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Roeland
treddie
Licensed Customer
Posts: 739
Joined: Fri Mar 23, 2012 5:44 am

Got it. Thanks for the info, Roeland!
Win7 | Geforce TitanX w/ 12Gb | Geforce GTX-560 w/ 2Gb | 6-Core 3.5GHz | 32Gb | Cinema4D w RipTide Importer and OctaneExporter Plugs.
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