3D Terrestrial Laser Scanning as a New Field Measurement and Monitoring Technique

3D terrestrial laser scanning is a relatively new, but already revolutionary, surveying technique. The survey yield a digital data set, which is essentially a dense “point cloud”, where each point is represented by a coordinate in 3D space. The most important advantage of the method is that a very high point density can be achieved, in the order of 5 to 10 mm resolution. In order to analyse the character and shape of the scanned surfaces it is necessary to convert the irregularly distributed point data into 3D surface information using surface reconstruction. The reconstructed surface can subsequently be visualized using a variety of 3D visualization techniques. From the reconstructed 3D surfaces, it is also possible to generate 2D profiles or elevation contour lines for use in regular GIS or CAD packages. A number of applications are described in this paper, which may illustrate the possible benefits of using laser scanning as a technique in engineering geological practice and research: volume analysis and monitoring, detailed and large-scale topographic mapping, tunnelling, rock face surveying, and digital outcrop mapping.