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CLOSE-RANGE PHOTOGRAMMETRY AS A TOOL IN GLACIER CHANGE 
DETECTION 
T. Pitkünen?, K. Kajuuttib 
"Institute of Photogrammetry and Remote Sensing, Helsinki University of Technolog 
tuija.pitkanen(hut.fi 
PDepartment of Geography, University of Turku 
kari.kajuutti@utu. fi 
KEY WORDS: Photogrammetry, close range, terrestrial, change detection, glaciology 
ABSTRACT: 
The shape and texture of ice surface can give us valuable information about processes affecting glaciers. This presentation introduces 
a procedure for making close-up digital elevation models (DEM) of glacier surface and the benefits of using these DEMs in 
glaciological change detection. They can be used to follow accurately the changes of different surface features like melt water 
channels, glacier tables, ablation hollows etc. The DEMs have been produced using digital photogrammetric methods. To keep the 
amount of ground control points reasonable concentric images have been connected to panoramic wide-angle images. Experimental 
research has been carried out using two study sites situated on Engabreen in the West Svartisen in Norway and on Hintereisferner in 
Austria. Test areas have been small, only 10 x 10 m. Tacheometer and GPS have been used for ground control measurements. The 
photography has been recorded once a year during a period of three years. DEMs have been constructed using commercial 
photogrammetric workstation and are very detailed with 20 —50 cm point density. Results indicate that close-up DEMs can be used to 
densify more sparse DEMs and to detect chances in ice structure and movements. 
I. INTRODUCTION The amount of supraglacial debris has also a major influence 
on the surface topography. As a matter of fact the whole 
1.1 Motivation glacier surface is full of features starting from large crevasses 
down to tiny holes and mounds. Melting and refreezing of ice 
Digital close-range photogrammetry can be used for detailed are common phenomena during the summer causing together 
modelling and visualisation. From instrumental point of view with glacier movement a numerous amount of surface 
it is a light and cost-effective method for measurements and features that form and reform throughout the melting season. 
visualisation of small objects or areas. Panoramic Some of these features can stay several years but many of 
photography gives the advantages of a wide angle image, them will last only days or even hours. (Benn and Evans 
such as a possibility to get close to an object and to decrease 1998: 228-230, Betterton 2001). As the photography was 
number of control points (Haggrén et al. 2001.) In this study repeated three times on two completely different 
we wanted to find out if panoramic images can be used for environments, it gives a good chance to get an overall idea 
photogrammetric DTM measurements and visualisation of what the surface changes are alike. 
temporal change in object. 
The glacier test sites are located on Engabreen in West 
1.2 Overview Svartisen in Norway and on Hintereisferner in Austria. The 
test areas are small, only 10 x10 m. The photography was 
Terrestrial photography has traditionally been used for repeated three times during a period of three years. The 
detecting the position of the glacier snout. In some cases the ground control points were measured with a tacheometer. On 
whole glacier has been tried to cover. There are extensive Engabreen the camera was standing on solid rock in front of 
series of photographs of some areas, especially the Alps, the glacier edge, giving the possibility to use same camera 
starting from the late 1800's. More recently aerial and places and ground control points throughout the study. As it 
satellite images have mostly replaced this type of was not safe to go on the ice, all the control points are in front 
photography. (Finsterwalder 1954, Gao and Liu 2001). of the glacier. On Hintereisferner it was not possible to 
However, there are still applications where terrestrial photograph or make tacheometer measurements from the 
photography is adequate (Theakstone 1997). The high sides of the glacier because of the loose gravel and masses of 
accuracy of the DEMs makes it possible to detect small rolling stones. Therefore all the camera places and control 
details on the glacier surface. Covering of large areas is, points were located on ice. 
however, quite laborious, but for a change detection in a 
limited area close-up views offer a very useful technique. The The lens distortions were corrected and single images were 
reformation of the glacier surface can be followed by combined to panoramic images. Panoramic stereo pairs were 
repeating the photography at the same place with a suitable oriented using digital stereo workstation. The DEMs were 
time frequency. In this study the photography was repeated measured from absolutely oriented stereo models. 
three times during a three years period. 
Changing weather conditions make the glacier surface a 
subject to many processes effecting its shape and structure. 
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