Investigation and calibration of pulsed time-of-flight

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Phil Marsh
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Investigation and calibration of pulsed time-of-flight

Post by Phil Marsh »

The attached thesis has two aims. The first one is the investigation and analysis of the errors occurring in the measurements with pulsed time-of-flight (TOF) terrestrial laser scanners (TLS). A good understanding of the error sources and the relationships between them is necessary to secure the data accuracy. They subdivided these errors into four groups: instrumental, object-related,
environmental and methodological. Based on their studies and the results obtained by other
researchers, they have compiled an error model for TLS, which is used to estimate the single-point
coordinate accuracy of a point in the point cloud, transformed to the specified coordinate system.

The second aim is to investigate systematic instrumental errors and performance of three pulsed
TOF laser scanners – Callidus 1.1, Leica HDS 3000 and Leica HDS 2500 – and to develop
calibration procedures that can be applied by the users to determine and correct the systematic
errors in these instruments. The investigations have been performed at the indoor 3D calibration
field established at KTH and outdoors. The systematic instrumental errors, or calibration
parameters, have been estimated in a self-calibration according to the parametric least-squares
adjustment in MATLAB. The initial assumption was that the scanner instrumental errors are
similar to those in a total station. The results have shown that the total station error model is
applicable for TLS as a first approximation, but additional errors, specific to the scanner design,
may appear. For example, they revealed a significant vertical scale error in the scanner Callidus
1.1, caused by the faults of the angular position sensor. The coordinate precision and accuracy of
the scanners, estimated during the self-calibration, is at the level of several millimetres for
Callidus 1.1 and Leica HDS 3000, and at the submillimetre level for Leica HDS 2500.

Please click here to read the full investigation.
http://www.laserscanning.org.uk/images/ ... flight.pdf

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