Digital Mapping in Polar Regions from Landsat Photographic Products: A Case Study
Landsat photographic products on the Space Oblique Mercator (SOM) projection are used to construct a map of Nordaustlandet (Svalbard), of known accuracy. The map includes ice divides. Accurately enlarged Landsat images were digitized. Combined digitizer and operator errors were 64 m, at the enlargement scale. Fifteen ground control points rixed the two scenes. RMS errors in control point identification were <123 m. Geographical coordinates were extracted by: 1) converting digitizer coordinates to SOM cartesian coordinates and 2) transforming these coordinates to latitude and longitude. This map production method is applicable to any imagery of known projection. The digitally stored map may be plotted on a variety of map projections and scales. Two problems in image interpretation were: I) shadows obscuring detail on NNE-facing coasts and 2) summer snow cover obscuring parts of the terrestrial ice cap margins, The map is similar to an east coast map produced from Landsat computer compatible tapes. Differences between the Landsat map and a 1:50 000-scale aerial photograph were <100 m.