Comparison of Time-of-Flight and Phase-Shift TLS Intensity Data for the Diagnostics Measurements of Buildings

Area of Science:

• Geomatics Engineering
• Civil Engineering
• Materials Science

Background:

• Terrestrial Laser Scanning (TLS) is a popular non-destructive testing (NDT) method for structural diagnostics and heritage assessment.
• TLS captures not only 3D coordinates but also backscattered laser intensity, offering insights into surface physio-chemical properties.
• Surface defects such as cracks, moisture, and biodeterioration can be identified using TLS intensity data.

Purpose of the Study:

• To compare the effectiveness of time-of-flight (TOF) and phase-shift (PS) terrestrial laser scanners for building diagnostics.
• To evaluate the potential of TLS intensity data for detecting defects in building walls.
• To assess how different scanner technologies influence the quality of radiometric point cloud information.

Main Methods:

• Utilized two TOF scanners (Riegl VZ400i, Leica ScanStation C10) and two PS scanners (Z + F 5016 IMAGER, Faro Focus3D).
• Collected TLS intensity data from multiple building wall samples.
• Analyzed point cloud intensity data to identify surface defects.

Main Results:

• Both TOF and PS scanners captured intensity data that could be used for defect detection.
• Differences in energy absorption and reflection between TOF and PS technologies may affect radiometric data quality.
• The study demonstrated the potential of TLS intensity for identifying various wall defects.

Conclusions:

• TLS intensity data is a valuable tool for non-destructive diagnostics of buildings and structures.
• The choice between TOF and PS scanners may influence the detail and reliability of defect detection based on intensity.
• Further research is needed to fully understand the nuances of each technology for specific diagnostic applications.