Characterization of the optical encoder angular noise from terrestrial laser scanners

Area of Science:

• Geomatics Engineering
• Structural Health Monitoring
• Metrology

Background:

• Rigorous statistical testing of deformation is essential for preventing structural collapses.
• Accurate noise characterization of terrestrial laser scanner (TLS) measurements, including angle correlations, is vital for deformation analysis.
• Existing methods often neglect the correlations between angular measurements in TLS data.

Purpose of the Study:

• To develop a method for accurately describing the noise in TLS measurements, specifically addressing correlations between angles.
• To improve the reliability of statistical testing for deformation monitoring.
• To enable the creation of fully populated variance-covariance matrices for TLS noise.

Main Methods:

• Utilizing a least-squares approximation to extract TLS point cloud geometry and analyze fitting residuals.
• Applying specific filtering techniques combined with maximum likelihood estimation.
• Quantifying the contributions of flicker noise and white noise in TLS measurements.

Main Results:

• Successfully extracted TLS point cloud geometry and analyzed residuals.
• Quantified flicker and white noise components.
• Established a method for generating fully populated variance-covariance matrices for TLS noise.

Conclusions:

• The proposed methodology accurately characterizes TLS measurement noise, including angular correlations.
• This advancement is critical for reliable deformation monitoring and structural integrity assessment.
• The results facilitate more robust statistical testing, enhancing structural safety.