| V. Kaufmann, MEASUREMENT OF SURFACE FLOW VELOCITY OF ACTIVE ROCK GLACIERS |
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Geographia Technica, Special Issue, 2010, pp. 68 - 81 MEASUREMENT OF SURFACE FLOW VELOCITY OF ACTIVE ROCK GLACIERS USING ORTHOPHOTOS OF VIRTUAL GLOBESViktor KAUFMANNABSTRACT: In this paper we demonstrate how multi-temporal high-resolution orthophotos taken from
virtual globes, such as Google Maps and Microsoft Bing Maps, can be used not only for the
detection of active rock glaciers but also for the precise measurement of flow/creep
velocities. Our study area covers the central and western part of the Schober Mountains,
which belongs to the Hohe Tauern range of the Austrian Alps. The present paper is focused
on three active rock glaciers, i.e. Leibnitzkopf, Tschadinhorn, and Ganot, which were
identified and examined for the first time based on the above mentioned freely available
image data. Two-dimensional flow/creep vector fields were determined using a Matlabbased
toolbox developed at our Institute. Methods of both photogrammetry and computer
vision were implemented to co-register the multi-temporal orthophotos and to precisely
measure motion parallaxes with sub-pixel accuracy. The results obtained were visualized
through vector plots, isotachs and computer animations. The accuracy of the displacement
vectors was thoroughly checked at stable non-moving regions in the surroundings of the
rock glaciers. The paper concludes with a summary of the pros and cons of the workflow
outlined. |
