Displacement Monitoring of the Slope at Tunnel Face Based on PhotoModeler Scanner System

Abstract

This paper describes a simple slope displacement monitoring system based on PhotoModeler Scanner. Multi-angle images of displacement observation points located in the slope at tunnel face were rapidly acquired by a cheap and calibrated CCD camera. After the image enhancement processing, images were imported into PhotoModeler Scanner system. Then, using several software function modules to process image data, we get the X-Y-Z three component coordinate values of all the displacement monitoring points. Through a long-term monitoring, each component displacement curve of the monitoring points was drawn out. In order to test the reliability of the results, three-dimensional coordinate values of each point were measured by the high-precision total station instrument simultaneously. These three-dimensional coordinate values were treated as true values. Under the requirements of the accuracy of 0.1 mm, the displacement values of photogrammetric measurement were compared to the true values. The results showed that, RMS (Root Mean Square) values of the most points were about ±2.0 mm, in addition to very few. And the total RMS value was ±2.8 mm. It indicates that the digital close-range photogrammetry based on PhotoModeler Scanner Systerm can satisfy the requirement of the general slope displacement monitoring. Moreover, the 3D displacement values got by our way can be used to appraise the security state of slopes in similar areas.