NPC-SPU: Nonlinear Phase Coding-Based Stereo Phase Unwrapping for Efficient 3D Measurement | JoVE Visualize

Area of Science:

Optics and Photonics
Computer Vision and Image Processing
Metrology

Background:

3D imaging using phase-shifting structured light is crucial for non-contact industrial measurement.
Existing methods like multi-frequency heterodyne (M-FH) and space domain modulation phase-shifting (SDM-PS) have limitations, including numerous required images or compromised accuracy, and are sensitive to motion.

Purpose of the Study:

To propose a novel nonlinear phase coding-based stereo phase unwrapping (NPC-SPU) method to overcome limitations of existing 3D imaging techniques.
To achieve accurate and robust 3D reconstruction with fewer patterns, especially in dynamic and complex scenes.

Main Methods:

Introduced a nonlinear distortion feature in the encoding stage while preserving phase codeword signal-to-noise ratio.
Developed a local phase unwrapping method using distortion information and a pre-calibrated stereo constraint system for phase ambiguity reduction.
Proposed a local phase correlation matching (LPCM) technique for lightweight and robust phase unwrapping, avoiding complex intensity kernel matching.

Main Results:

The NPC-SPU method significantly enhances 3D reconstruction performance in scenarios with large depth, large disparity, complex colored structures, and dynamic scenes.
In dynamic environments (20mm/s), NPC-SPU achieved a lower measurement error rate (0.7829%) compared to traditional three-frequency heterodyne (T-FH) (6.4962%) using only 3 patterns (vs. 9 patterns).
NPC-SPU demonstrated superior measurement accuracy (0.1102 mm) compared to the SDM-PS method (0.3232 mm) using the same number of patterns (3).

Conclusions:

The proposed NPC-SPU method offers a robust and accurate solution for 3D imaging, overcoming motion sensitivity and pattern requirements of traditional methods.
NPC-SPU provides significant advantages in terms of accuracy, efficiency, and applicability to challenging 3D reconstruction scenarios.
This advancement holds promise for improving industrial measurement and 3D reconstruction technologies.