Fig. 1. The relationship between corresponding points on two lines under perspective transformation.

Fig. 2. Get the ideal unwrapped phase map from the real unwrapped phase map in the calibration data.

Fig. 3. The three steps of the proposed method to use the LUT.

Fig. 4. The flowchart of the traditional method and the proposed method.

Fig. 5. The diagram of the experimental setup.

Fig. 6. Ensure the measured plane is parallel to the calibration plane, moving it to the positions of 4.80 mm, 11.20 mm, and 21.80 mm, employing the traditional method and proposed method for 3D imaging, and calculating the RMSE. (a) The measurements of the traditional method and their RMSEs. (b) The measurements of the proposed method and their RMSEs.

Fig. 7. Place the marked steps on a special platform, and apply the traditional method and proposed method for 3D imaging. Extract the marker points from surfaces A and B, and plot the height curves of ground truth, traditional method, and proposed method. (a) 3D imaging of the steps using the traditional method and proposed method. (b) Plot the height curve for the points extracted on surface A, using traditional method and proposed method; their RMSEs are 0.155 mm and 0.015 mm, respectively. (c) The result of surface B via the same process, and their RMSEs are 0.301 mm and 0.019 mm, respectively.

Fig. 8. 3D imaging for objects with traditional method and proposed method. (a) The inclined plane. (b) The small ball. (c) The statue.

Fig. 9. The relationship between the SNR and the accuracy (RMSE).