A Compact BRDF Scanner with Multi-conjugate Optics

Reflectance, represented as Bidirectional reflectance distribution functions (BRDFs), is an important scene property that we wish to obtain from the real world together with the scene’s 3D shape. BRDF acquisition, however, remains a difficult task because it is time-consuming and requires huge and costly devices. To make the BRDF acquisition easier and accessible to everyone, we develop a compact projector-camera-based BRDF scanner with coaxial multi-conjugate optics, where the sensor/source is conjugate with the Fourier transform plane of the objective lens, and the camera/projector pupil is conjugate with the sample plane. It consists of only off-the-shelf components, and the carefully designed conjugate optics make the entire system compact. BRDFs of outdoor objects are scanned to show the validity of our device.