Metric performance of a high-resolution laser scanner

The recent emergence of high-resolution laser scanning technology offers unprecedented levels of data density for close range metrology applications such as deformation monitoring and industrial inspection. The scanner's pulsed laser ranging device coupled with beam deflection mechanisms facilitates rapid acquisition of literally millions of three-dimensional point measurements. Perhaps the greatest advantage of such a system lies in the high sample density that permits accurate and detailed surface modeling as well as superior visualisation relative to existing measurement technologies (eg. digital cameras). As with any metrology technique, measurement accuracy is critically dependent upon instrument calibration. This aspect has been, and continues to be, an important research topic within the photogrammetric community. Ground-based laser scanners are no exception, and appropriate calibration procedures are still being developed. The authors' experience has shown that traditional sensor calibration techniques, in some instances, can not be directly applied to laser scanners. This paper details an investigation into the calibration and use of the Cyrax 2400 3D laser scanner. With its variable spatial resolution (up to 0.5mm sample interval at a 50m range) and high accuracy (manufacturer's specifications: +/- 4mm in range, +/- 6mm in position), the Cyrax offers great potential for close range (up to 100m) metrology applications. A series of rigorous experiments were conducted in order to quantify the instrument's precision and accuracy.