Infrared BRDF spatial scanning measurement with an optimized rotation strategy of a robotic arm

•We established ageometry mapping from the goniometer to BRDF angles for a robotic arm.•An optimized rotation strategy was proposed to improve BRDF measurement speed and resolution.•The BRDF of different samples with specular or diffuse reflection qualities were measured. The bidirectional reflection distribution function (BRDF) reflects the optical reflection properties of opaque materials over the entire hemispherical space. Exciting measurements of infrared BRDF systems based on robotic arms are discrete in space since the incident and reflection angles were coupled deeply. In this paper, a mapping from BRDF angles to goniometer angles was developed, and the two sets of angles were decoupled using an optimized spatial rotation strategy with two scanning modes. The measurement covered the full BRDF hemispherical space. The measurement speed and resolution in the specific scanning directions were significantly improved. Meanwhile, the measurement accuracy was not reduced. An infrared BRDF measurement system using the proposed strategy was developed to measure five different samples from high to low reflectance with specular or diffuse reflection qualities. The qualities demonstrated by the calculated BRDF distributions were consistent with the infrared optical characteristics of all samples, verifying the effectiveness of the proposed system.