Adaptive digital fringe projection technique for high dynamic range three-dimensional shape measurement

Area of Science:

• Optical Metrology
• 3-D Shape Measurement
• Digital Image Processing

Background:

• Measuring objects with high reflectivity variation poses challenges for optical methods.
• Image saturation in fringe patterns leads to phase and measurement errors.
• Existing high dynamic range (HDR) 3-D scanning methods are time-consuming.

Purpose of the Study:

• To present an adaptive digital fringe projection technique for accurate 3-D shape measurement.
• To overcome image saturation and achieve high signal-to-noise ratio (SNR) for surfaces with large reflectivity variations.
• To reduce scanning time compared to conventional HDR methods.

Main Methods:

• Adaptive adjustment of pixel-wise fringe pattern intensity based on captured image saturation.
• Reducing projected intensity in bright regions to avoid saturation.
• Utilizing maximum intensity (255) in dark regions to maintain high SNR.

Main Results:

• The proposed technique effectively avoids image saturation across surfaces with significant reflectivity differences.
• High signal-to-noise ratio (SNR) is maintained for both bright and dark surface regions.
• Experimental results demonstrate improved 3-D measurement accuracy.

Conclusions:

• The adaptive digital fringe projection method offers an efficient and accurate solution for 3-D shape measurement of challenging surfaces.
• This technique significantly improves upon existing HDR 3-D scanning methods by reducing processing time and enhancing accuracy.