Acknowledgements

The authors would like to thank Michael Laise and Axel Koeppel for their technical support, and Karol Myszkowski for his valuable comments. This work has been partially funded by the DFG Emmy Noether fellowship (Le 1341/1-1) and the Max Planck Center for Visual Computing and Communi-cation (BMBF-FKZ01IMC01). In fluorescent materials, energy from a certain band of incident wavelengths is reflected or reradiated at larger wavelengths, i.e. with lower energy per photon. While fluorescent materials are common in everyday life, they have received little attention in computer graphics. Especially, no bidirectional reflectance measurements of fluorescent materials have been available so far. In this paper, we develop the concept of a bispectral BRDF, which extends the well-known concept of the bidirectional reflectance distribution function (BRDF) to account for energy transfer between wavelengths. Using a bidi-rectional and bispectral measurement setup, we acquire reflectance data o