Project PI: Paul Morin, University of Minnesota Polar Geospatial Center
Surface topography is among the most fundamental Earth Science data sets, essential to a wide range of activities, including ice mass-balance, hazard assessment and mitigation, hydrologic modeling, solid earth dynamics, route planning and many others. The National Geospatial-Intelligence Agency, MAXAR (formerly DigitalGlobe), and the Polar Geospatial Center built a near-seamless archive of polar sub-meter stereo imagery that consists of millions of stereo pair images from the Worldview-1, -2, and 3 satellites. Using photogrammetric algorithms, they are able to construct digital elevation models from the stereo pairs, enabling mapping of surface features at the 2-meter scale for the first time.
The Surface Extraction from TIN-based Search-space Minimization (SETSM) algorithm, initially designed to extract elevation data over ice sheets, has been refined and optimized to handle stereoscopic imagery over any landcover. After an initial preprocessing step that corrects the source imagery for sensor-specific detector alignment artifacts, SETSM takes the two source images and derives increasingly detailed elevation models using its pyramid-based approach.
The poles now have better dependable topography than almost anywhere else on earth. In addition, the ice on earth has better topography than the land surface on Earth. The team has produced over 200,000,000 km2 2 meter posting topography covering the Arctic over 8 times. The data has been adopted by Greenland, Iceland and Canada as their national standard elevation data.
After the polars were completed, the work has moved on to mapping the rest of the Earth’s landmass.