An Accurate Phase Measuring Deflectometry Method for 3D Reconstruction of Mirror-Like Specular Surface

Measurement of specular surface shape is still a challenging task for existing 3D scanning techniques. In this paper, an accurate phase measuring deflectometry method is investigated for 3D reconstruction of mirror surfaces. To calibrate the system parameters, a standard flat mirror is used. By the reflected checkerboard pattern displayed by the LCD screen, the camera intrinsic parameters are calibrated firstly. The last orientation of calibration mirror is aligned as the reference plane. With such a calibration manner, intrinsic camera parameters, lens distortion and the LCD position can be determined efficiently. By displaying both horizontal and vertical Gray code plus sinusoidal shifting patterns on the LCD screen, dense surface gradient field is calculated with the proposed slope calculation method, and then integrated to retrieve precise 3D surface shapes. The experiments conducted with both flat and concave mirror surface demonstrate that high precision measurement results can be obtained.