Hullin, Matthias B.Lensch, Hendrik P. A.Raskar, RameshSeidel, Hans-PeterIhrke, IvoM. Chen and O. Deussen2015-02-272015-02-2720111467-8659https://doi.org/10.1111/j.1467-8659.2011.01891.xThis paper deals with the challenge of physically displaying reflectance, i.e., the appearance of a surface and its variation with the observer position and the illuminating environment. This is commonly described by the bidirectional reflectance distribution function (BRDF). We provide a catalogue of criteria for the display of BRDFs, and sketch a few orthogonal approaches to solving the problem in an optically passive way. Our specific implementation is based on a liquid surface, on which we excite waves in order to achieve a varying degree of anisotropic roughness. The resulting probability density function of the surface normal is shown to follow a Gaussian distribution similar to most established BRDF models.