Inter-sphere consistency-based calibration for camera–projector pairs

We propose an inter-sphere consistency-based method for camera–projector pairs (CPPs) calibration. Previous sphere-based calibration works have only considered independent constraints from each sphere, and thus require at least three spheres for calibration. In this paper, it is shown that additional constraints can be extracted from consistency between estimated parameters from different spheres, which we term the inter-sphere consistency (ISC). Such ISC constraints facilitate more flexible and easy-to-use calibration using only two spheres, which has been considered a challenging ill-posed problem and never been well addressed before. Extensive experimental results have been provided for the validation.