Calibration of a Terrestrial Laser Scanner - Institute of Geodesy and ...
Calibration of a Terrestrial Laser Scanner - Institute of Geodesy and ...
Calibration of a Terrestrial Laser Scanner - Institute of Geodesy and ...
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7Summary7.1 Conclusions<strong>Terrestrial</strong> laser scanning is a promising technique <strong>and</strong> has the potential to be adapted as an equal survey¬ing technique. <strong>Laser</strong> scanners are now in the second to third generation <strong>of</strong> development<strong>and</strong> fulfill severalgeodesists' needs. Investigation regarding potentials <strong>and</strong> limitations have been launched some years ago.Independent examinations from different institutions have established a comprehensive knowledge regard¬ing properties, influencing parameters, performance <strong>and</strong> limitations. The collaboration between geodesists<strong>and</strong> manufacturers results in improvements, which ease the use <strong>of</strong> laser scanners <strong>and</strong> significantly improvethe accuracy.The calibration <strong>and</strong> investigation <strong>of</strong> the laser scanner 'Imager5003' <strong>of</strong> Zoller+Frohlich was carried outregarding several aspects,such as:• distance precision <strong>and</strong> accuracy• angle precision <strong>and</strong> accuracy• instrumental errors• non-instrumental errorsThe results have shown that laser scanners <strong>of</strong>fer a high potential regarding high accuracy within themillimeter-scale. The most critical factor is thereby defined by the distance measurement system. Sincethe distance measurement isbased on prismless measurements, the signal-to-noiseratio influences theprecision significantly. The signal-to-noise ratio is generally affected by three parameters: the range, thereflectivity <strong>of</strong> the object <strong>and</strong> the anglecan be reduced by an adequate filtering technique,alongthe measurement direction.<strong>of</strong> incidence. This thesis showed that the noise related to the distancewhich takes into account the orientation <strong>of</strong> the noiseSystematic effects produced by methodological errors may also affect the data significantly. The investiga¬tion regardingthe wobble <strong>of</strong> the vertical axis <strong>and</strong> the errors <strong>of</strong> the collimation axis showed that there areindeed systematic effects, especially for short ranges below ten meters. Furthermore, the verification <strong>of</strong> thelaser scannersystem <strong>and</strong> its performance, i.e.measurement noise <strong>and</strong> instrumental errors, over time arerecommended either with asystem calibration or with a component calibration.The two discussed applications regarding static laser scanning showed the potential for applications in thefield <strong>of</strong> engineering geodesy. Point clouds defining objects in a high point resolution achieved results fromthe whole object <strong>and</strong> also in only discrete points. The flow directions <strong>of</strong> a road section or the displace¬ments on a tunnel face after excavation establish a new method <strong>of</strong> interpretation, especiallyin the relatedengineering fields <strong>of</strong> urban water management <strong>and</strong> engineering geology. The accuracy in the millimeter
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