CHANGE DETECTION OF A MOUNTAIN SLOPE BY MEANS OF GROUND-BASED PHOTOGRAMMETRY: A CASE STUDY IN THE AUSTRIAN ALPS
The surface topography of mountainous areas is often subject to continuous spatio-temporal changes due to gravitational and climatic forces. In this paper we focus on periglacial phenomena, e.g., permafrost creep and other gravitational mass movements (solifluction, etc.) Various in-situ and other n...
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| Format: | Text |
| Language: | English |
| Published: |
2004
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.532.1940 http://www.mountaincartography.org/publications/papers/papers_nuria_04/ladstaedter.pdf |
| Summary: | The surface topography of mountainous areas is often subject to continuous spatio-temporal changes due to gravitational and climatic forces. In this paper we focus on periglacial phenomena, e.g., permafrost creep and other gravitational mass movements (solifluction, etc.) Various in-situ and other non-contact (remote sensing) measurement techniques can be applied in order to derive metric information of surface deformation and flow velocity. In the present work we have investigated the potential of ground-based (terrestrial) photogrammetry for monitoring mountain slopes of local extent (typically 10 - 10 m) using a low-cost digital camera and applying a digital photogrammetric workflow. A case study has been carried out in the Ötztal Alps, Austria. We selected the Outer Hochebenkar rock glacier since it has been subject to intensive research for many decades. Ground-based photogrammetry is feasible, because photogrammetric baselines can be easily established on the opposite slope, thus allowing multiple stereoscopic coverage of the area of interest. The main task of the case study was to derive 3D displacement vectors of the surface. The paper describes the various pre-processing steps involved, i.e. camera calibration, scanning of the analog photographs and digital resampling for obtaining geometrically refined images. Control points needed for exterior orientation were taken from existing aerial photographs. The measurement of dense fields of displacement vectors is carried out using the in-house developed ADVM (Automatic Displacement Vector Measurement) software, which was originally developed for |
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