A Fixed Terrestrial Photogrammetric System for Landslide Monitoring

Though landslide alert is based on monitoring systems capable of high frequency, highly accurate, continuous-operation photogrammetry has been used since long time to periodically control the evolution of landslides. In this chapter, a fixed terrestrial stereo photogrammetric system is presented. It has been developed to monitor landslides and, in general, changes in digital surface model (DSM) of the scene framed by the cameras. The system is made of two single-lens reflex (SLR) cameras, each contained in a sealed box and controlled by a computer that periodically shoots an image and sends it to a host computer. Once an image pair is received, the DSM of the scene is generated by digital image correlation on the host computer and made available for archiving or analysis. The system has been installed and is being tested on the Mont de la Saxe landslide, where several monitoring systems are active and provide reference data. Instability of the camera attitude has been noticed and corrected with an automated procedure by image resampling. First comparisons with interferometric synthetic aperture radar data show a good agreement of the displacements over time