MEASUREMENT OF SURFACE FLOW VELOCITY OF ACTIVE ROCK GLACIERS USING ORTHOPHOTOS OF VIRTUAL GLOBES

Viktor KAUFMANN

ABSTRACT: 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 Matlab-based 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.

Keywords: Google Maps, Microsoft Virtual Earth, rock glacier, monitoring, flow/creep velocity, visualization, Hohe Tauern range, Austria.

Full article here