(The Eurographics Association, 2018) Havran, Vlastimil; Hosek, Jan; Nemcova, Sarka; Cap, Jiri; Reinhard Klein and Holly Rushmeier
We present our progress to the on-site measurement of the spatially varying surface reflectance represented by bidirectional texture function (BTF). This requires a physical realization of a portable instrument that can be brought to the sample, outside the laboratory. We discuss our motivation, the main issues, and challenges for making such an instrument possible. We focus on the design of the mechanical parts that are required for an easy manipulation of the device on site and describe our experiences with the instrument in practice. The design uses a miniaturized rotary light stage. It allows for measurement of HDR images with the acquisition rate of 1000 HDR images per minute, where one HDR image consists of 4 individual exposures.