Precise Calibration for Virtual Binocular Stereovision System Based on Biprism

Virtual binocular stereovision system (VBSS) based on biprism provides an effective and compact solution for 3-D measurement. The calibration accuracy of the system is important for precise measurement. Generally, the structure parameters need to be optimized before measurement, especially for VBSS due to its narrow field of view, limited depth range, and short baseline. In this article, we proposed a precise calibration method for the structure parameters of VBSS considering its imaging characteristics. The multiple spatial distance constraints were designed and incorporated into the objective function with the epipolar constraint. The structure parameters can be nonlinearly optimized by the improved objective function. Experiments were designed to compare the performance of the proposed method with four existing methods. Furthermore, the optimization strategy of the proposed method was compared with three other strategies. The results demonstrate the feasibility of the proposed method and it can effectively improve the calibration accuracy for VBSS.