Photogrammetry-Based Monitoring for the Continuous Management of Cultural Heritage: A Case Study of the Petroglyphs of Cheonjeon-ri, Ulju

Abstract. The Petroglyphs of Cheonjeon-ri are a significant cultural heritage site that offers important insights into cultural developments from prehistoric times through ancient history. However, as an outdoor site, the Petroglyphs of Cheonjeon-ri are highly vulnerable to environmental hazards such as heavy rainfall, typhoons, and climate anomalies, which can lead to physical deterioration. Their location within an active watershed further increases their susceptibility to surface erosion, periodic flooding, and biological colonization, accelerating the weathering of the carvings. These factors underscore the urgent need for continuous and systematic monitoring, as well as early detection, to ensure their long-term preservation. This study applies photogrammetry as a digital documentation method to support the safeguarding of the Petroglyphs of Cheonjeon-ri. 3D models were produced by using photographs captured under varying working distances and camera angles and evaluated for realism and accuracy. Simulated damage conditions were also introduced to assess the effectiveness of photogrammetric change detection through Cloud-to-Mesh (C2M) distance analysis. The results demonstrate that multi-angle image acquisition at relatively close distances significantly improves model precision and enhances the detectability of surface deformations. Artificially damaged areas were clearly identified through color-mapped analysis, confirming the potential of photogrammetry-based 3D modeling as a practical tool for monitoring heritage sites at risk. This study provides foundational insights toward optimized acquisition strategies for photogrammetric monitoring and highlights its value as an accessible, repeatable, and sustainable method for the continuous preservation of outdoor cultural heritage.