Applying PSD Analysis in Ring-Structured-Light 3D Measurement

Error elimination is very important in 3D measurement with ring-structured-light. A method has been proposed, which includes the following procedures. First, acquire ring-structured-light images and extract their stripe center. Second, find the base-circle center of the stripe center locus by curve fitting, using the least squares method. Subsequently unfold the stripe center locus along its base-circle. In the waveform of the unfolded view, there exist an eccentricity error component and an ellipse shape error component. The frequencies of these two error components are different from the frequency of detail component. They can be separated in the unfolded view by power spectrum density (PSD) analysis. Based on their formation principles, eccentricity error and ellipse error can be separated and eliminated, and the accuracy of the measurement can be improved. Experiments have demonstrate its applicability.