Precision verification of a simplified three-dimensional DIC method

The traditional three-dimensional (3D) digital image measurement technique uses at least two images captured from different positions to determine the 3D coordinate of an object. One disadvantage of this method is that the mechanical and optical properties of the image capture devices are not fully identical, and the calibration procedure is quite complicated. This paper introduces a simplified 3D digital image correlation (DIC) method, in which only one image capture device is used. The theoretical measurement error equation is derived and experimentally verified. Experimental results show that distortion correction plays an important role in the improvement of measurement precision. After a radial distortion correction, the measurement precision of the object distance can reach 0.0043%. The optimal camera spacing should be set from 1/50 to 1/30 of the object distance, to obtain a satisfactory precision.

Research highlights
► A three-dimensional DIC method using a single camera is proposed.
► Systematic and random errors of measurement using this method are discussed.
► The precision of the proposed technology is good.
► The proposed method is applied to the analysis of a forming limit diagram (FLD).