Calibration and Testing of a Terrestrial Laser Scanner

Terrestrial laser imaging systems offer a new means for rapid precise mapping of objects up to ranges of up to a few hundred metres from the instrument location. The high sampling frequency (e.g., several kilohertz) available from such instrumentation can provide a spatial data density of directly observed co-ordinates far in excess of that available with photogrammetric techniques. For structural monitoring applications, this permits measurement of entire surfaces rather than a few discrete points, thus providing a wealth of information about the deformation modes of a body. This paper conveys the findings of a preliminary study of the resolution and accuracy of a commercially available laser-scanning system. Testing was conducted on a first order EDM calibration baseline and on a three-dimensional deformationmonitoring network. Single point range accuracies of ±3-5 cm (1σ) were achieved. Evidence of uncompensated systematic errors, probably due to instrumental set-up errors and target centre reduction, was detected.