USING GEODETIC AND LASER SCANNER MEASUREMENTS FOR MEASURING AND MONITORING THE STRUCTURAL DAMAGE OF A POST BYZANTINE CHURCH

This paper presents a detailed description of the methodologies and the actions taken for determining and monitoring the deformations and micro-movements of the post-byzantine Church of Megali Panayia in Samarina. An assessment is also provided of the first results obtained from the repeated observations and their combined adjustment, followed by a discussion on their reliability. The reported analysis focuses on the following crucial aspects: the accuracy and the stability of georeferencing, which is fundamental to make comparisons between different multi-temporal measurements; and the computation of deformation based on the survey observations between the established control points. Emphasis is given to the presentation of the results using a detailed 3D model of the church, created from terrestrial laser scanner point clouds. The methodology applied involves the analytical combination of multi-source measurements, i.e. GPS observations and classical surveying observations using appropriate high-end theodolites and total stations, in order to achieve the highest possible accuracy. The use of a time-of-flight laser scanner provided data for the 3D model creation. From the re-measuring of this network four times during a five month period and by comparing and analyzing the results of all measurements, it was possible to detect and obtain crucial information about the building’s structural behaviour and the surrounding terrain’s displacements an