Advancing Material Appearance Measurement: A Cost-effective Multispectral Imaging System for Capturing SVBRDF and BTF

This paper introduces a novel system for measuring the appearance of materials by capturing their reflectance represented by Spatially Varying Bidirectional Reflectance Distribution Function (SVBRDF) and Bidirectional Texture Function (BTF). Inspired by goniospectrophotometers, our system uses a fully-aligned and motorized turntable that rotates the sample around three axes to scan the entire hemispherical range of incident-reflection directions. The camera remains fixed while the light source can be rotated around one axis providing the fourth degree of freedom. To ensure high precision color measurement and spectral reproduction for reliable relighting purposes, we use a high-resolution multispectral camera and a broadband LED light source. We provide an overview of our instrument in this paper, and discuss its limitations to be addressed in the future works.