Automated three-axis gonioreflectometer for computer graphics applications

Abstract

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.

High-Speed Measurement of BRDF using an Ellipsoidal Mirror and a Projector

“…A gonioreflectometer [6] is a device that can separately rotate a light source and a sensor. However, dense measurement of BRDFs requires excessive amounts of time because reflected light must be recorded for all combinations of lighting and viewing directions.…”

An experimental study of the correlation between surface roughness and light scattering for rough metallic surfaces

“…[33][34][35] The gonioreflectometer performs rapid measurements of the BRDF of flat, isotropic sample surfaces over the visible spectrum and over most of the incident and reflection hemispheres. Special design was applied to enable BRDF measurements at grazing angles up to and slightly above 85 • .…”

Research on the model of spectral BRDF for space target surface material

“…Various theoretical models such as Lambertian model, Torrance-Sparrow model and Cook-Torrance model have been established [3][4][5][6][7][8]. However, there are some defects in the previous work because of the limitation of wavelength range Figure 1.…”