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I know a bit about controlling dispersion, but I am interested in learning how to use IOR (index of refraction) to mimic specific materials, like a sodium-rich glass. What is the best way to configure this? Am I just missing something?

Answers regarding Yafaray are preferred, but answers regarding other engines (Lux, etc.) would be interesting too.

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  • $\begingroup$ I feel like, 9 years hence, there much be a new good answer for this question $\endgroup$ Apr 19, 2022 at 22:35

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In physics, dispersion is caused because different wavelengths of light (colors) have different speeds than each other depending on the medium, and therefore have more or less refraction than other wavelengths.

Now in Yafaray, you have the basic IOR field, as seen below. But, the dispersion field is simply one field. To get accurate dispersion, you would have to enter the IOR for every single wavelength of light, because dispersion is not linear. It is a complicated relationship. But, since Yafaray only has a single slider (Dispersion Power) that affects dispersion, I'm not sure if it is the right tool.

Here is a good list of refractive indices.


Yafaray glass settings


My comment stated: 'Two words use Cycles.', but I didn't know that Cycles doesn't have dispersion/caustic support (YET). You might want to check out LuxRender, but I believe that it hasn't been updated since 2009.

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