Monotonic phase coding with dynamic boundary alignment for high-speed 3D profilometry.

Area of Science:

• Optical Metrology
• 3D Reconstruction
• Computational Imaging

Background:

• Fringe Projection Profilometry (FPP) is crucial for 3D shape measurement.
• Traditional methods struggle with dynamic scenes due to numerous patterns.
• Temporal Phase Unwrapping (TPU) aims to resolve phase ambiguities efficiently.

Purpose of the Study:

• To develop a robust and efficient TPU framework for FPP.
• To reduce the number of projected patterns for dynamic measurements.
• To achieve accurate absolute phase retrieval with fewer patterns.

Main Methods:

• A novel framework combining three phase-shifting patterns and one coded pattern.
• Monotonic encoding strategy to reorganize phase sequences and broaden coding range.
• Gradient-Constrained Local Search (GCLS) for dynamic alignment of codeword edges.

Main Results:

• Achieved accurate absolute phase retrieval with a reduced pattern set.
• Demonstrated a 66% reduction in projected patterns compared to traditional methods.
• Maintained submillimeter accuracy in experimental measurements.

Conclusions:

• The proposed TPU framework enhances efficiency and robustness in FPP.
• This method enables high-speed dynamic 3D measurements with high accuracy.
• Significant reduction in patterns offers practical advantages for real-world applications.