3D PHOTOGRAMMETRY MODELING FOR SAFETY MONITORING OF FORTRESS WALLS

In the monitoring to prevent collapse or tipping in the structure of linear-shaped fortress walls, the record of shapes like slope or protrusion is very important(Jo and Hong, 2019). As the way to record the shapes, laser scan or photogrammetric technology is employed. A laser scan that has to install several points of measurement has a limitation in recording them if the terrain is undulating, or the structure becomes huge. Photogrammetry has a shortening effect in terms of cost and process(Kim, 2020) compared to that. This study examined a measure for producing a 3D mesh model with aerial and ground photography for fortress walls. In addition, this study tested if it would be possible to monitor the slope and protrusion, etc. of fortress walls. This study tested the accuracy of the model produced with photogrammetry to use in the diagnosis and monitoring of the structural safety of fortress walls. The research subject was Korea's cultural heritage, Seosan Haemieupseong Fortress, and a model was produced for the section about 100m of the fortress walls. The positional accuracy, elevation/section accuracy, LOD, and texture joint precision of two models (Model A & Model B) produced with photogrammetry and laser scan were compared. This study revealed that the model produced at LOD Level 4 would be effective for monitoring the displacement since it could measure the shape, curvature, and slope of stones of the fortress walls.