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DOCUMENTATION OF THE MOVEMENT
OF THE HINTERES LANGTALKAR ROCK GLACIER
V. Kaufmann *, R. Ladstidter
Institute of Remote Sensing and Photogrammetry
Graz University of Technology, Austria
viktor.kaufmann @tugraz.at
KEY WORDS: Environment, Geomorphology, Change Detection, Monitoring, Aerial, Multitemporal, Digital, Photogrammetry
ABSTRACT:
Rock glaciers are striking phenomena of high mountain permafrost. These periglacial landforms are composed of rock and ice and
creep downslope at a typical rate of a few decimeters per year. This movement and other surface changes can be measured by various
observation techniques. In this paper a digital-photogrammetric approach to rock glacier monitoring is described based on multi-
temporal aerial photographs. A software package, ADVM (Automatic Displacement Vector Measurement), has been developed,
which automatically derives 3D displacement vectors from the photographs. The basic concepts of this software will be given first,
followed by a detailed description of a new constrained image matching technique, implemented in the current ADVM 2.0 version.
Finally, the successful application of the software is shown in a case study: The spatio-temporal evolution and dynamic behavior of
the Hinteres Langtalkar rock glacier (Hohe Tauern range of the Austrian Alps) was reconstructed using aerial photographs (1954-
1999). Results of the practical investigations are presented graphically and numerically.
1. INTRODUCTION
Rock glaciers are complex landforms of cold mountain areas
and are composed of a mixture of rocks and ice. These unique
features of mountain permafrost creep downslope by force of
gravity in a steady-state mode due to the mainly plastic
deformation of the interstitial ice, thus forming a characteristic
surface topography consisting of transverse furrows and ridges
(Barsch, 1996; Haeberli 2000). Rock glaciers play a decisive
role in permafrost research, since recent climatic warming has
triggered permafrost degradation. This fact may cause natural
hazards, which are already observable in high-mountain areas,
e.g. in the European Alps. The rock glacier system must be
understood very well in order to correctly correlate observables
of rock glaciers, e.g., creep velocity, temperature and ice
content of the inner core, with climatic parameters, e.g., mean
annual air temperature (Harris et al., 2001).
Contemporary rock glacier research is highly interdisciplinary.
One special issue is to better understand rock glacier mechanics
(Arenson et al., 2002; Ladanyi, 2003). Detailed knowledge of
rock glacier kinematics is indispensable in this context. The
creep process and also basal sliding at distinct shear horizons
cause deformation of the permafrost body. Measurements of
internal deformation, e.g., using inclinometers and magnet
rings, can only be carried out in boreholes, which are expensive
to drill and therefore limited to a few examples worldwide. In
contrast, however, visible deformation of the rock glacier
surface may be observed directly.
Monitoring of the temporal change of the surface geometry has
already a long history. Kääb et al. (2003) give an overview of
the state-of-the-art of the various monitoring techniques.
Remote sensing, i.e., obtaining information without direct
contact with the object, has been identified as one of the most
powerful techniques. Referring to this technique, the
Corresponding author
893
development of digital photogrammetric procedures using aerial
photographs has made substantial progress, and several applied
studies have been published (Kiib et al., 2003; Kaufmann &
Ladstádter, 2002; Kaufmann & Ladstáüdter, 2003).
In this paper we want to introduce our in-house developed
software package ADVM (Automatic Displacement Vector
Measurement). After describing the basic concepts of ADVM
some technical details will be explained. Consequently, the
applicability of the software will be shown in a case study.
Finally, the paper concludes with recommendations for further
developments.
2. METHOD
The first version of the ADVM software was developed in
1999. Since then, it has been further developed and used
successfully in several rock glacier monitoring projects. This
paper, however, will not describe the digital work flow of
ADVM as a whole but focuses on a new matching algorithm,
which has been developed especially for such monitoring tasks.
The new algorithm, implemented in the recent ADVM 2.0
version, allows for high precision, multi-temporal point transfer
in (pseudo-)rectified stereo pairs and simultaneous 3D
reconstruction of displacement/flow vectors.
2.1 Basic Concepts
In this Section some of the basic concepts of the ADVM
software will be outlined. The pseudo-orthophoto concept,
being the key issue, will be discussed first. Some basics of the
multi-photo constrained matching (MPCM) algorithm will then
be described in brief. Finally, the extension of MPCM for
multi-temporal point transfer is proposed.