Optical low-cost and portable arrangement for full field 3D displacement measurement using a single camera

Abstract

In the current paper, an optical low-cost system for 3D displacement measurement based on a single camera and 3D digital image correlation is presented. The conventional 3D-DIC set-up based on a two-synchronized-cameras system is compared with a proposed pseudo-stereo portable system that employs a mirror system integrated in a device for a straightforward application achieving a novel handle and flexible device for its use in many scenarios. The proposed optical system splits the image by the camera into two stereo images of the object. In order to validate this new approach and quantify its uncertainty compared to traditional 3D-DIC systems, solid rigid in and out-of-plane displacements experiments have been performed and analyzed. The differences between both systems have been studied employing an image decomposition technique which performs a full image comparison. Therefore, results of all field of view are compared with those using a stereoscopy system and 3D-DIC, discussing the accurate results obtained with the proposed device not having influence any distortion or aberration produced by the mirrors. Finally, the adaptability of the proposed system and its accuracy has been tested performing quasi-static and dynamic experiments using a silicon specimen under high deformation. Results have been compared and validated with those obtained from a conventional stereoscopy system showing an excellent level of agreement.

Ultraviolet Diffraction Assisted Image Correlation (UV-DAIC) for Single-Camera 3D Strain Measurement at Extreme Temperatures

“…Not only is stereo DIC more expensive due to the cost of additional cameras and lenses, but the multiple cameras must be synchronized, which requires additional hardware further driving up the complexity and cost. The level of synchronization necessary for accurate stereo DIC can be time consuming and difficult to achieve [18]. In addition to the temporal calibration to ensure both cameras are taking pictures of the sample at the same time, the cameras must be calibrated spatially as well.…”

Accurate 3D Shape, Displacement and Deformation Measurement Using a Smartphone

“…Moreover, a commercial stereo-DIC system is costly for resource-limited institutions and for professionals in other fields who have demands in 3D deformation measurements. To mitigate this problem, various single-camera stereovision techniques, including mirror-based [9,10,11,12], prism-based [13,14], and diffraction grating-based [15,16] approaches, have been developed by incorporating a set of planar mirrors, a prism or a diffraction grating, and have been shown to be effective in 3D shape and deformation measurements. With the aid of these additional optical devices, the incoming light rays are equally split into two sub-images or diffracted into two diffraction images projected at different angles on the camera sensor.…”

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

“…Through the optical adapter, two different views of the object surface from different optical paths can be imaged onto one image plane. The optical adapter can be planar mirrors [17,18], a bi-prism [19], or a diffraction grating [20,21]. Compared with the conventional double-camera stereo vision system, the single camera system can fully meet the stringent synchronization requirement and is more compact.…”

“…Moreover, the single camera system can also reduce the hardware cost. The main drawback of the single-camera-based 3D DIC methods [17][18][19][20][21] is that each view should only be imaged on half of the sensor plane. In this case, the spatial resolution is reduced by at least 50%.…”