Datensatz

Zusammenfassung

In fluorescent materials, light from a certain band of incident wavelengths is
reradiated at longer wavelengths, i.e., with a reduced per-photon energy. While
fluorescent materials are common in everyday life, they have received little
attention in computer graphics. Especially, no bidirectional reradiation
measurements of fluorescent materials have been available so far. In this
paper, we extend the well-known concept of the bidirectional reflectance
distribution function (BRDF) to account for energy transfer between
wavelengths, resulting in a Bispectral Bidirectional Reflectance and
Reradiation Distribution Function (bispectral BRRDF). Using a bidirectional and
bispectral measurement setup, we acquire reflectance and reradiation data of a
variety of fluorescent materials, including vehicle paints, paper and fabric,
and compare their renderings with RGB, RGBxRGB, and spectral BRDFs. Our
acquisition is guided by a principal component analysis on complete bispectral
data taken under a sparse set of angles. We show that in order to faithfully
reproduce the full bispectral information for all other angles, only a very
small number of wavelength pairs needs to be measured at a high angular
resolution.