Automated Camera Exposure Control for Accuracy-Enhanced Stereo-Digital Image Correlation Measurement

Area of Science:

• Mechanical Engineering
• Optical Measurement
• Image Processing

Background:

• Digital Image Correlation (DIC) is a widely used non-contact technique for measuring deformation.
• Traditional stereo-DIC systems often rely on fixed camera exposure settings, which can lead to suboptimal image quality under varying lighting conditions.
• Achieving high-quality speckle image pairs is crucial for accurate stereo-DIC measurements.

Purpose of the Study:

• To present an automated camera exposure control method for two-camera stereo-DIC systems.
• To enhance the accuracy and robustness of stereo-DIC measurements.
• To ensure high-quality speckle image capture under dynamic and varying environmental conditions.

Main Methods:

• Development of an automated system to determine optimal camera exposure and average grayscale for reference image acquisition.
• Implementation of adaptive camera exposure adjustments to compensate for ambient light variations during testing.
• Validation through varying illumination tests and translation tests.

Main Results:

• The automated method successfully captures high-quality speckle image pairs in both reference and deformed states.
• Experimental validation demonstrated superior performance compared to fixed camera exposure time methods.
• The system proved effective and robust across different illumination levels and during translation tests.

Conclusions:

• The proposed automated camera exposure control method significantly improves stereo-DIC measurement accuracy.
• The technique is practical and effective, even in challenging environments like high-temperature experiments.
• This advancement offers a more reliable approach for quantitative deformation analysis using stereo-DIC.