3D digital image correlation using a single 3CCD colour camera and dichroic filter

Abstract

In recent years, three-dimensional digital image correlation methods using a single colour camera have been reported. In this study, we propose a simplified system by employing a dichroic filter (DF) to replace the beam splitter and colour filters. The DF can be used to combine two views from different perspectives reflected by two planar mirrors and eliminate their interference. A 3CCD colour camera is then used to capture two different views simultaneously via its blue and red channels. Moreover, the measurement accuracy of the proposed method is higher since the effect of refraction is reduced. Experiments are carried out to verify the effectiveness of the proposed method. It is shown that the interference between the blue and red views is insignificant. In addition, the measurement accuracy of the proposed method is validated on the rigid body displacement. The experimental results demonstrate that the measurement accuracy of the proposed method is higher compared with the reported methods using a single colour camera. Finally, the proposed method is employed to measure the in- and out-of-plane displacements of a loaded plastic board. The re-projection errors of the proposed method are smaller than those of the reported methods using a single colour camera.

A non-target structural displacement measurement method using advanced feature matching strategy

“…There are limitations also for current practice of vision-based displacement measurement. Digital image correlation (DIC) and DIC-based template matching are the most popular methods (Zhong et al, 2017, 2018; Zhong and Quan, 2017, 2018), while it has to create manual speckles on the surface of measurement structures to achieve good accuracy of DIC (Ye et al, 2016c). Manual targets are necessary to improve the performance of DIC-based template matching (Brownjohn et al, 2017).…”

A Simple and Practical Single-Camera Stereo-Digital Image Correlation Using a Color Camera and X-Cube Prism

“…As shown in Figure 1b, the optical setup of the method is similar to the color separation device assisted one, but it uses two polarizers with different polarization angles to remove the interference between the two views. Recently, a seemingly simpler dichroic filter (DF) [9] was also used as a color separation device to realize full-frame single-camera stereo-DIC measurement as shown in Figure 1c.…”

“…First, the ghost image reflected from the rear surface of the DF will degrade the imaging quality of the blue channel. Second, the refraction effect presented when the blue light passes through the DF can lead to considerable measurement error [9].…”

A Cross-Dichroic-Prism-Based Multi-Perspective Digital Image Correlation System

“…Yu proposed using a single high-speed color CMOS camera to perform high-speed 3D-DIC measurements without an additional triggering device [18]. Zhong used a dichroic filter to replace the beam splitter and color filters [19]. This method has considerable advantages, such as simple optical paths, a system requirement of only one color camera, two mirrors, and a cube prism.…”

“…Bandpass filters are unnecessary due to the high performance of the cross dichroic prism, and the three view angles can simultaneously occupy the entire CCD without reducing the resolution and consequently maintain DIC measurement accuracy. At the same time, the system has been simplified compared with our previous system [19]. There is no longer a need for bandpass filters in the proposed system; only two planar mirrors are required as opposed to the three Wang needed, and the two beam splitters are replaced by a cross dichroic prism, which reduces costs.…”