Great ablation of the Werenskiold Glacier created the need of recording the changes particularly superficial ones, after melting of its icingsGround stereophotogrammetric photos done during the Polar Expedition of the Polish Academy of Sciences in 1983 enabled to prepare a map in the scale of 1:10,000 covering by its two sheets the whole glacier, a system of open crevasses inclusive. The map presents the actual state of the glacier and enables a comparison with earlier photogrammetric measurements carried out several times since 1957.
The paper presents methods of area calculation, which may be applied for big geodesic polygons on the ellipsoid. Proposal developed by the authors of this paper is discussed. The proposed methods are compared with other, alternative methods of area calculation of such polygons. Test calculations are performed for administrative units in Poland. The obtained results are also compared with areas of those units registered in statistical annals. Utilisation of the equal-area map projections of the ellipsoid onto a plane seems to be the best solution for the discussed task. In the case of small distances between points we may expect accurate results of calculations, since the area size is influenced by the projection reductions only, which are small in such cases. In some cases their influence on results of calculations may be neglected. Then, only re-calculation of co-ordinates from the GRS80 ellipsoid to the cartographic, equal-area projection is required.