Development of a BSDF Measurement Device : Design and Optimization of Light Source and Detector for Material Light Scattering Analysis

One way to describe how a surface or material scatters light is through the Bidirectional Scattering Distribution Function (BSDF) data. As the name implies, this is a function that describes how much light is scattered in a specific direction when light from another direction illuminates a material. Although the human eye can detect most scattering of light, it is often necessary, for example in photorealistic rendering or materials science, to quantify the scattering across various wavelengths and angles of incident light and detection. BSDF data for materials is most often obtained through empirical studies. In this project, an optical scattering measurement device is developed to accurately measure BSDF data from materials. This report focuses on the development of the light source and the detector. A light source emitting white light was designed, together with a camera detector with three different sensitivity curves, to obtain wavelength range-specific results when using the device. The response curves of the detector are linear for all three color channels, as expected. This allows for the exposure time to vary, but still getting comparable data across the different detection angles. The collimated light beam shows some irregularities in intensity and color along the beam cross section. This is only a problem for samples with irregular surfaces.