Among optical properties required for characterizing visual appearance in any lighting and viewing conditions, the most fundamental ones play an important role in predictive rendering. Spectroscopic ellipsometry is useful to acquire the complex indices of refraction of any homogeneous material. A multiscale approach using fundamental optical properties that are the components of the complex dielectric tensor of all the material compounds acquired separately is illustrated using automotive paints as an example.
Patrick Callet, "nmmm "nano-micro-meso-macro" Colour and appearance – a multiscale approach" in Proc. IS&T 25th Color and Imaging Conf., 2017, pp 28 - 33, https://doi.org/10.2352/ISSN.2169-2629.2017.25.28