Application of Terrestrial Laser Scanning to Determine Deformations - Practical Aspects

Abstract

When using laser scanning for deformation analysis of a given object, there are no pre-signalled points or identical points to compare between two epochs, so we can judge for whether an object deforms only by modelling the surface of the object. There are a number of challenges in this regard presented in the paper. The first challenge is that for the deformation analysis the configuration of the measurement parameters is no longer set by the surveyor-engineer by the number and position of the observed points, but from the laser scanner. Only the location of the scanner and the scanning density could be controlled. The second challenge is to expand the error model, as the surface modelling is included in the deformation process. This unifies both the metrological and the model errors that arise from the insufficient knowledge of the object and the simplification of its surface. All these challenges are oriented to the created 3D surface model. In addition, the metrological aspects of the use of laser scanners should be considered, especially for applications where the determination of the deformation requires high accuracy. A number of conclusions and recommendations are formulated. The influence of the factors influencing the accuracy of ground laser scanning in the deformation study is summarised, and the influence of the external orientation ang georefering of the point cloud on the accuracy of the digital model is established. Preliminary assessment of the accuracy of the TLS results are given. Justification of the reliability of the determined deformations through TLS is presented. Technological scheme and recommendations for determination of deformations with TLS is shown.