(The Eurographics Association, 2015) Havran, V.; Reinhard Klein and Holly Rushmeier
The accurate BTF data representation requires specialized measurement gantries, some of them designed as gonireflectometers. These consist of an illumination source and a camera mounted on two robotic arms, one degree of freedom possibly achieved by rotation stage which a measured sample is mounted on. While there are several variations of the gonioreflectometer gantry, the principle of all remains the same, positioning directly the illumination and detector on a hemispherical surface over a sample. We analyze the positioning error of such gonioreflectometers. The input parameters are the required spatial resolution of a BTF sample and the distance between the camera used as a detector and the BTF sample. Our analysis confirms that the requirements for mechatronic actuators for the positioning of the sample and arms are very high and near the limit of state of the art technology.
(The Eurographics Association, 2015) Kettner, L.; Raab, M.; Seibert, D.; Jordan, J.; Keller, A.; Reinhard Klein and Holly Rushmeier
We introduce the physically-based Material Definition Language (MDL). Based on the principle of strictly separating material definition and rendering algorithms, each MDL material is applicable across different rendering paradigms ranging from realtime over interactive solutions to advanced light transport simulation.