Combining 3D Geometric Documentation with Infra-Red Thermography for Enhancing Cultural Heritage

Abstract. The effective preservation and condition assessment of cultural heritage structures require advanced non-destructive testing (NDT) techniques that can identify structural issues without inflicting harm. This study proposes a novel methodology that integrates Infrared Thermography (IRT) with three-dimensional (3D) geometric documentation to create a comprehensive diagnostic system for heritage conservation. The method was applied to walls adjacent to the Library of Pantainos in the Ancient Agora of Athens, Greece. Geometric documentation was achieved through terrestrial surveying and photogrammetric techniques to generate detailed 3D models. For this purpose, non-destructive testing (NDT) techniques were applied. Specifically Infrared Thermography (IRT), high-resolution infrared thermograms were acquired using a thermal camera under controlled environmental conditions and systematically mapped onto the geometric documentation products, enabling precise localization of thermal anomalies and structural deterioration. In addition, digital microscopy (DM) was also employed to categorize stones and mortars. 
This combined approach allows for precise localization and visualization of thermal anomalies, such as rising damp, material deterioration, and structural weaknesses. In Wall 1, the method identified rising damp accumulation leading to salt crystallization, while in Walls 2 and 3, severe material degradation and thermal stresses were observed. By integrating interdisciplinary data, this technique enhances the accuracy and efficiency of condition assessments, supporting informed conservation decisions. The study demonstrates the significant potential of combining IRT with 3D documentation to improve diagnostic capabilities and offers a robust framework for future applications in cultural heritage conservation.