TLS-Detectable Plane Changes for Deformation Monitoring

Area of Science:

• Geomatics Engineering
• Geodetic Monitoring
• Geophysical Surveying

Background:

• Terrestrial laser scanning (TLS) is widely used for deformation monitoring of built structures.
• TLS requires mathematical models, typically planes, to analyze point cloud data across different time epochs.
• Accurate detection of small geometric changes is essential for reliable monitoring.

Purpose of the Study:

• To quantify the sensitivity of TLS in detecting small parameter changes of a plane.
• To compare the performance of different scanning devices for deformation monitoring.
• To establish best practices for utilizing TLS in structural health assessment.

Main Methods:

• Controlled shifting and tilting of a physical plane representation.
• Multiple scans of the plane using two different TLS devices after each controlled change.
• Calculation and statistical analysis of plane parameters derived from point cloud data.

Main Results:

• TLS successfully detected shifts in the millimeter range and tilts of 150″ for a 1m plane.
• A robotic total station demonstrated twice the precision of TLS, despite lower data density and speed.
• Scan repetition proved vital for identifying gross errors and estimating precision.

Conclusions:

• TLS is capable of detecting sub-millimeter deformations, but precision varies between devices.
• Robotic total stations offer superior precision for deformation monitoring applications.
• Repeating scans multiple times is a critical recommendation for ensuring data reliability and accurate precision assessment in TLS-based monitoring.