Evaluating the Application of Close-Range Photogrammetry in Determining the Horizontal Displacement of High Structural Elements - A Case Study of the Thermal Station at Tishreen University

Abstract

Large horizontal displacements and tilts in tall structural elements such as towers and factory chimneys resulting from soil movement or earthquakes may lead to their collapse. The traditional methods of tilt monitoring require direct contact with the monitored buildings. Although the measurement results of sensors are accurate, sensors are typically cumbersome to deploy and can only provide local and relative deformation information Other monitoring methods do not require direct contact with the building, such as those using TLSs, GBInSAR, and photogrammetry; this last method had been used to obtain the geometric measurement of a 3D model, deformation data such as the displacement and inclination of buildings.In this study, close-range photogrammetry based on the principle of Structure from Movement technique (SfM Photogrammetry) had been used to monitor high structural elements because it considers safety and economical method where it isn't required direct contact with the monitored building, addition to low effort, short practical time and low budget; where the chimneys of the thermal station located at Tishreen University as a (case study). Results were then evaluated by comparing them with the traditional survey methods based on the use of the total station measurements. The results show that the value of the maximum displacement at the highest level, determined by using an uncalibrated mobile phone built-in camera and SfM photogrammetry (0.081 m) is approximately equal to twice the displacement and inclination determined by traditional surveying (0.049 m); but through some precautions and conditions, the accuracy of this method can be increased.

Keywords

• close-range photogrammetry
• sfm
• monitoring
• displacement
• 3d point cloud