Error model of direct georeferencing procedure of terrestrial laser scanning

Abstract

Processing of raw point cloud data obtained as a result of terrestrial laser scanning (TLS) sometimes involves georeferencing, i.e. transformation of point cloud data to an external coordinate system. This paper focuses on defining the error model of point positions obtained through a "station-orientation" procedure of direct georeferencing. The original error model presented by the authors relevant in this field is partly altered. All modifications are explained in detail within the paper and the reported model is statistically verified based on the carefully conducted experiment using Leica ScanStation P20 scanner. The obtained values of the uncertainty measures of direct georeferencing Which are of a few millimetre magnitude prove that this procedure can be efficiently used for planning and carrying out even more demanding surveying tasks, including those during monitoring and maintenance of constructed facilities. Additionally, traversing capabilities of terrestrial laser scanners tightly connected with direct georeferencing should contribute to mass introduction of laser scanning into the construction industry thanks to its similarities to the highly automated procedures of polar surveying and traversing which are traditionally employed among surveyors.