Automated three-axis gonioreflectometer for computer graphics applications.

In A. Duparre, B. Singh, and Z-H Gu, editors, Advanced Characterization Techniques for Optics, Semiconductors, and Nanotechnologies II, volume Proceedings of SPIE Vol. 5878, pages 5878--29. SPIE, SPIE, Bellingham, WA, July 2005.

We describe an automated three-axis BRDF measurement instrument that can help increase the physical realism of computer graphics images by providing light scattering data for the surfaces within a synthetic scene that is to be rendered. To our knowledge, the instrument is unique in combining wide angular coverage (beyond 85° from the surface normal), dense sampling of the visible wavelength spectrum (1024 samples), and rapid operation (less than ten hours for complete measurement of an isotropic sample). The gonioreflectometer employs a broadband light source and a detector with a diffraction grating and linear diode array. Validation was achieved by comparisons against reference surfaces and other instruments. The accuracy and spectral and angular ranges of the BRDFs are appropriate for computer graphics imagery, while reciprocity and energy conservation are preserved. Measured BRDFs on rough aluminum, metallic silver automotive paint, and a glossy yellow paint are reported, and an example rendered automotive image is included.

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