This chapter describes the design and the implementation of a virtual goniopho-tometer dedicated to the representation of Bidirectional Scattering DistributionFunctions (BSDF) for wet materials. Input surfaces are represented by geometricmeshes associated with an elementary reflectance. Our system relies on a hemi-spherical sensor with uniform solid angle cells, capable of gathering very finedetails. The angular reflectance and transmittance of any type of structure can beestimated, including multi-layered materials. In order to show the interest of thissystem, a series of simulations is provided for virtual material samples made up ofa rough surface covered with a water layer of varying thicknesses.