CALIBRATION OF TERRESTRIAL LASER SCANNERS CALLIDUS 1.1, LEICA HDS 3000 AND LEICA HDS 2500

Abstract

The paper presents the results of the self-calibration of three commercial terrestrial laser scanners (TLS) – Callidus 1.1, Leica HDS 3000 and Leica HDS 2500 – performed at the specially established indoor 3D calibration field. The systematic instrumental errors have been estimated in the selfcalibration assuming that they were similar to those in the total station. Afterwards, we compared the ranges, horizontal directions and vertical angles derived from the scanning with the true ones in order to reveal the possible presence of some non-modelled systematic trends. In this way, a significant vertical scale error in the scanner Callidus 1.1 has been found, presumably due to the maladjustment of the scanning mirror. Other significant errors are the vertical index error in Leica HDS 3000 and horizontal axis error in Leica HDS 2500. Due to the physical limitations of the calibration field, the estimation of some of the instrumental errors, especially collimation error, was complicated by their significant correlation with the Helmert transformation parameters. We have also estimated the target coordinate accuracy. The RMS errors in the position of the calibration targets are 2.9 mm, 1.6 mm and 0.3 mm, for Callidus 1.1, Leica HDS 3000 and Leica HDS 2500, respectively, at the distances to the scanner of up to 10 m. In spite of the problems encountered during the self-calibration, the results are believed to contribute to a better knowledge of TLS performance.