Polarization patt provides additional information besides spectral signatures.It can be used in many applications,such as navigation,defect detection and object identification.A novel polarization camera composed of four synchronized cameras is proposed,and it can realize real-time polarization measurement.This study particularly concentrates on the geometric calibration of the system.The projection model is analyzed and the multi-camera calibration algorithm is proposed.Firstly,each camera is calibrated separately using planar patts,and then the geometric calibration algorithms are performed.Due to the geometrical constraint,a global optimization method results in smaller estimation uncertainties.A mean rotation error of 0.025° and a mean translation error of 0.26 mm are achieved after geometric calibration.The images are rectified to establish a correspondence among cameras and are combined to acquire the polarization measurement.The polarization patt of the skylight is measured by the system and the results are consistent with the previous studies.