Visual Condition Assessment Of Stone MonumentsAnd Associated Property Supported By The Use OfPhotogrammetric Models

Abstract

Decay mapping supported by photogrammetric techniques is a new approach of condition assessment of entire stone buildings. The technique is based on the evaluation of stereoscopic photopairs. They were studied in this work for the improvement of the conventional mapping process. Hence, this project covers investigations on the recognition and mapping of weathering phenomena and decay severity by the use of photogrammetric models. Two systems have been chosen for the examination of stereoscopic images: a mirror stereoscope as a low cost application which is easy to handle and an advanced analytical workstation. The workstation can fulfil different demands because of it's comprehensive facilities. The unit is linked to a CAD computer system. Obtained data can be processed automatically with Geographic Information Systems (G.I.S). These systems provide a combination of the mapping results with related measurements for the evaluation of environmental effects and parameters of stone decay or the calculation of required preservation measurements and envisaged treatments on the building. Both photogrammetric techniques have been proved to be reliable and efficient applications for visual condition assessments in a case study of an 18TM century stone mansion in the town centre of Dublin, Ireland. It was established that photogrammetric condition assessment of stone surfaces bears certain advantages compared to conventional in-situ-mapping directly on the location. Comparative studies have shown that a higher degree of mapping accuracy and working efficiency was achieved by photogrammetry. Transactions on the Built Environment vol 15, © 1995 WIT Press, www.witpress.com, ISSN 1743-3509