Automatic extrinsic calibration of display-camera system using an annular mirror

Our work focuses on the extrinsic calibration of a display-camera system where the camera has no direct view of the display. An annular planar mirror is used to reflect the display so that the camera can capture the reflection images. The position of the mirror can be obtained after outer circle is detected. The position parameters are determined uniquely by putting two orthogonal lines in the background and optimized by re-projecting the inner circle to the image plane. The display pixels are encoded using gray code and its imaged position in the mirror can be obtained by solving the PnP problem. Finally, the real extrinsic parameters between the camera and the display are obtained according to the mirror imaging principle. Our approach is simple and fully automatic without any manual intervention. Both simulation and real experiments validate our approach.