Monitoring of Glacier Surfaces with Photogrammetry, a Case Study of the Triglav Glacier

Abstract

The relatively rapid changes of the shape and volume of glaciers that have been recorded in the last few decades can be monitored and recorded in different ways. Photogrammetry, the science of obtaining metrical data about the environment from photographs, is especially appropriate for this task. Modern photogrammetric methods enable solutions for complex tasks such as the reconstruction of the spatial position of a glacier in previous time periods from non-technical (amateur, archive, etc.) photographs. A simpler way is to photograph a glacier with special photogrammetric cameras that have a known and stable construction. In the case study of Triglav glacier, a photogrammetric team coped with a major professional challenge: how to reconstruct the three-dimensional shape and surface of the glacier from archive photographs. These photographs have been taken regularly almost every month from two fixed standpoints over many years with a simple non-metrical Horizont camera. The solution of this task initially required the calibration of the Horizont camera to establish the geometrical features of the photographs. In addition, a helicopter survey and a terrestrial survey of the glacier using a stereo-technique were done during a major inter disciplinary expedition in September 1999. The archive photographs were linked to the new metrical photographs through selected tie points. Additionally, photographs from the cyclical aerial survey were used. Existing computer programs had to be augmented, and several new programs had to be developed since standard photogrammetric methods were not sufficient to solve the problem The final aim of this part of the project was the determination of a surface model of the glacier in different time sequences and the computation of the volume differences in different time sequences. Experts from other sciences could use these results for various studies, e. g., estimating correlations between climate changes and the shrinkage of the glacier. In this paper, the main phases of the photogrammetric work are described. An original solution of the problem is presented in more detail, and partial and expected final results are described. Modern methodology is proposed for the future monitoring of the glacier.