Assessment of SRTM, ICESat, and Survey Control Monument Elevations in Canada

The Shuttle Radar Topography Mission (SRTM) has provided homogeneous and highly accurate data for Digital Elevation Models (DEMs). It is important to realize that the SRTM DEM represents the Earth’s surface (vegetation, snow) as seen by a C-band SAR in February 2000 and not necessarily the bare terrain. The accuracy of the DEMs depends on various factors including the terrain roughness/slope, land-cover, snow/ice, and vegetation. Herein, an accuracy assessment of the C-band SRTM DEM is performed through comparisons with independent elevation data obtained from the laser altimetry mission ICESat (4.7 million footprints) and terrestrial height information at 33,000 survey control monuments in Alberta, Canada. Temporal elevation changes due to snow cover and vegetation are considered and presented for the provinces of Quebec and Alberta. The analysis focuses on both data and datum issues, which are required to provide a realistic assessment of the achievable accuracy.