Digital Image Correlation (DIC) is a powerful technique for measuring and analyzing material deformations, strain, and displacement. Depending on your testing requirements, you can choose between 2D vs 3D DIC (Stereo). Both methods have unique advantages, limitations, and ideal use cases. Let’s explore these two approaches in detail.
2D vs 3D DIC comparison
| 2D | 3D | |
|---|---|---|
| Description | 2D DIC is based on taking sequences of images with one camera and analyzing the planar (x, y) changes on the test piece’s surface under load. The test piece is assumed to be fully planar and to remain planar throughout the entire measurement. It is also required to be perpendicular to the camera‘s optical axis. Any out-of-plane motion and/or misalignment of the optical axis is going to result in errors in correlation. | 3D DIC is based on taking sequences of images with a pair of synchronized cameras and analyzing the 3D (x, y, z) changes on the test piece’s surface under load. The test piece is viewed in two planes and its surface is reconstructed in three-dimensional space using stereo triangulation. Out-of-plane motions are captured by placing the camera’s optical axes at an angle towards the test piece. |
| Advantages | ❖ Quick setup compared to 3D DIC ❖ Cost-efficient in terms of both hardware and software ❖ Lower hardware requirements (due to capturing images from only one camera) ❖ Can be very precise for some applications if the scene is well prepared and all conditions are met (Requires the camera to be positioned perpendicular to a planar deformation surface in order to give accurate results.) | ❖ Higher accuracy in most applications ❖ Captures unexpected out-of-plane motions ❖ Can capture complex shapes and determine the size of the measured object |
| Disadvantages | ❖ Accuracy is lower than for 3D DIC ❖ Limited applications due to out-of-plane motion introducing errors ❖ Even small misalignment of the optical axes and/or out-of-plane motion causes uncertainties in the measurement ❖ Can’t capture complex shapes or determine the size of the measured object | ❖ More difficult setup in terms of camera position, lighting and camera calibration ❖ Higher cost of hardware and software ❖ Higher hardware requierments – disk space and processing power |
| Example Applications | ❖ Testing of thin materials such as tensile test specimen and sheet metals (unaxial tensile test with a planar shaped specimen or three/four-point flexural testing) ❖ Crack testing (crack strain and propagation on specimen surface) ❖ Testing of biomedical soft tissues in biaxial testing | ❖ Material testing – uniaxial testing with dog bone shaped specimen, testing of complex shaped specimen ❖ Crash/impact testing – car components, safety helmets ❖ Vibration analysis – ODS analysis for vibrating parts |
Typical applications where 2D DIC is insufficient in comparison with 3D DIC
Certain scenarios require the precision and capabilities of 3D DIC over 2D DIC:
❖ Measurement of complex shaped specimen (curved shapes, convex or concave specimen) – 2D DIC can not sufficiently capture out-of-plane deformations
❖ Large deformations – materials undergoing large deformations (malleable metals) typically show displacement in all three dimensions – 2D DIC can not capture displacement in all three axes
Summary
2D DIC is ideal for planar events with simple shapes and small deformations. Cost-effective and quick to set up for well-prepared scenes (provide accurate results when the camera is perpendicular to a deforming area that has to be planar).
3D DIC excels in capturing out-of-plane motion, large deformations, and complex shapes, offering unmatched accuracy and flexibility in challenging scenarios.
If you’re looking for a reliable solution for 2D DIC, explore our AMEE 2D VEX for precise video extensometry or AMEE 2D for a flexible and modular optical measuring system. For advanced 3D DIC capabilities, check out AMEE 3D VEX for high-precision measurements or AMEE 3D, a versatile system designed for complex 3D deformation analysis.
