Factors to be considered in establishing a scanning laboratory for testing the accuracy of terrestrial laser scanning technologies

Abstract

Laser scanning is a 21st century mapping technique that is used to generate high density point cloud data in three dimensions (3D). The 3D scans can be used for surveying, mapping and monitoring of rock mass movement in mining. For high precision and reliable work, the instrument must be used correctly, regularly calibrated and checked to ensure that it constantly performs according to manufacturer's specifications. In this study, a Leica Total Station TCR 1201+ and a Trimble S6 Total Station were used to establish accurate coordinates for a control beacon and scanning targets. Thereafter, the scanning of the targets was carried out using a FARO Focus XD 130 terrestrial laser scanner. A comparison was conducted using the coordinates from the terrestrial laser scanner and total station to examine the point accuracy of the FARO scanner. The result from the comparison between the laser scanners coordinates and the total station coordinates showed that the FARO Focus is capable of producing accurate point cloud data that can be used for the purpose of monitoring underground rock mass movements. Lessons learnt during the development of the short-range scanning laboratory are summarised as factors to be considered when establishing such a laboratory. These include, operator knowledge, skill and work flow, robust target design, scanning geometry, full target visibility during scanning, calibration of instruments, laser scanner field of view and application of systematic error propagation during measurements.