Moisture is one of the main factors in the deterioration of heritage buildings, causing mould, unwanted parasites, and the decanting of salts, which, in turn, aggravate such degradation. The existence of moisture not only affects the building aesthetically, but is also evidence of bad conservation conditions. It is thus extremely important to verify and assess the extent of the moisture, even though it may not be confirmed by mere visual inspection. This article describes an innovative and straightforward procedure to automatically show where moisture appears, as well as the affected area. The procedure is based on the use of 3D laser scanner surveying data for documentation purposes of historic buildings. Data are processed off-line in order to analyse the laser reflectivity level. The method is not intrusive, allows large areas to be covered in a short time, and does not interact with the materials, which makes it optimal for application to these special buildings. Hence, professionals of the conservation sector will have objective and comprehensive information on moisture damage, helping them to take decisions on the action to be undertaken. The results achieved in the Cathedral of Ciudad Rodrigo (Spain) are shown to demonstrate the utility of the proposed method.Keywords: Moisture detection, Multi-point humidity measurement, Moisture optical measurement systems, 3D laser scanning, Index of reflectivity, Surface reflectivity measurement
Research objectiveThe present work is aimed at defining a novel, practical method for obtaining 3D digital models that clearly show where moisture appears, and also where it is likely to appear, in heritage buildings. Alternative methods in use are improved, and decision making on the corrective and preventive conservation measures to be adopted by cultural heritage owners or managing organizations will be facilitated. In addition, the competitiveness of related conservation and restoration enterprises will be encouraged.To this end, an applied research approach is proposed, which combines state-of-the-art 3D data acquisition, with a tailored computational algorithm for managing the reflectivity index provided by laser scanning devices. Hence, a useful unique digital model, including geometrical, colour, and reflectivity information of complex shaped objects, could be readily obtained, thereby favouring not only the cataloguing, but also revealing the moisture content and extension of the original sites.Time, expenditure, and areas to be cleared up can be clearly defined by the proposed method, which has been implemented through a practical tool for handling 3D point clouds, giving support to current and further automatic procedures.
