A Direct Georeferencing Method for Terrestrial Laser Scanning Using GNSS Data and the Vertical Deflection from Global...

Area of Science:

• Geoscience
• Geomatics
• Geodesy

Background:

• Terrestrial laser scanning (TLS) generates high-accuracy point clouds crucial for geoscience.
• Accurate georeferencing of TLS data to a global frame (e.g., GRS 1980) is essential.
• Traditional georeferencing requires numerous Global Navigation Satellite System (GNSS) points to estimate seven Helmert parameters.

Purpose of the Study:

• To propose a novel method for direct point cloud georeferencing into the geocentric coordinate frame.
• To reduce the dependency on a large number of GNSS referencing points.
• To provide an alternative georeferencing solution for scenarios with limited GNSS accessibility.

Main Methods:

• Direct georeferencing using vertical deflection from a global Earth gravity model.
• Integration of terrestrial laser scanning (TLS) data with minimal GNSS measurements.
• Validation through a field test comparing the proposed method with classical georeferencing.

Main Results:

• The proposed method requires only two georeferencing GNSS points.
• Field test validation showed maximum differences of 7 mm and a standard deviation of 8 mm for coordinate components.
• The method proves effective even with a limited number of GNSS points, such as in urban canyons.

Conclusions:

• A new, efficient method for direct point cloud georeferencing has been developed.
• This approach significantly reduces the number of required GNSS points for accurate georeferencing.
• The method offers a viable alternative for laser scanning data georeferencing, particularly in GNSS-constrained environments.