Displayed as 20m-contour lines underlain by a 1993 orthophoto. The main problem in generating DTMs with this method is its inaccuracy above snowfields and in shady areas. Next we created orthophotos of all DTMs which are subsequently needed for the measurement of rock glacier-movement. It compares the position of a certain feature in two orthophotos which show the same region at the two different years. The displacement between the features is measured.
Many features are too small to be identified in both pictures.
Measurements within the vicinity of snow are not possible. Modelled permafrost distribution and rock glaciers. Conclusion Digital photogrammetry produces dense information in a rather short time. Hence, the analysis of high-flown aerial photographs is a useful and effective method to examine rock glacier activity as long as the user is aware of the inaccuracies mentioned above.