Topographic mapping by laser altimetry

The prime objective of NASA's Arctic Ice Mapping project is to provide accurate ice sheet elevation data for the purpose of change detection. The airborne laser altimetry system ATM, developed by NASA, was successfully used in three missions in Greenland. This paper provides some background information about the ATM system and describes the tests that have been carried out to derive digital elevation models and to extract ice features from the raw data. After transforming the raw data into local coordinate systems, a simple thinning scheme is applied to reduce the redundancy. The digital elevation models are derived either from the original or from the thinned data sets by planar interpolation. Six parallel strips in different areas were bridged together and the resulting elevation model was used to map ice sheet features, such as undulations and lakes.