Sub-Pixel Extraction of Laser Stripe Center Using an Improved Gray-Gravity Method.

Area of Science:

• Computer Vision
• Metrology
• Optical Engineering

Background:

• Accurate profile measurement is crucial for line structured light sensors (LSLS).
• Sub-pixel level laser stripe center extraction is a fundamental challenge in LSLS applications.
• Existing methods may struggle with complex stripe geometries or computational efficiency.

Purpose of the Study:

• To propose an improved gray-gravity method (IGGM) for accurate laser stripe center extraction.
• To enhance sub-pixel coordinate determination for profile measurements.
• To evaluate the method's performance on various stripe types and complex surfaces.

Main Methods:

• Initial center point computation using the gray-gravity method (GGM).
• Robust fitting of points with the moving least squares algorithm to obtain tangential and normal vectors, and radius of curvature.
• Adaptive rectangular region definition based on curvature for refined center coordinate recalculation.
• Monte Carlo analysis for center uncertainty estimation.

Main Results:

• The IGGM successfully extracts sub-pixel accurate center coordinates for laser stripes.
• The method demonstrates robustness for both smooth stripes and those with sharp corners.
• Experimental results on stairs and screw surfaces validate the effectiveness of the IGGM.
• High accuracy is achieved at a relatively low computational cost.

Conclusions:

• The proposed IGGM offers a significant improvement for laser stripe center extraction in LSLS.
• It provides a computationally efficient and accurate solution for profile measurement.
• The method's adaptability to different stripe shapes makes it broadly applicable.