Abstrakt
In coloured media, the index of refraction does not decrease monotonically with increasing wavelength, but be- haves in a quite non-monotonical way. This behaviour is called anomalous dispersion and results from the fact that the absorption of a material influences its index of refraction.
So far, this interesting fact has not been widely acknowledged by the graphics community. In this paper, we demon- strate how to calculate the correct refractive index for a material based on its absorption spectrum with the Kramers-Kronig relation, and we discuss for which types of objects this effect is relevant in practice.