Interferometric Synthetic Aperture Radar (IFSAR) Alaska

The U.S. Geological Survey (USGS) National Geospatial Program (NGP) developed the Alaska Mapping Initiative (AMI) to collaborate with State and other Federal partners in Alaska to acquire 3-dimensional elevation data to improve statewide topographic mapping products. AMI coordinates Federal activities through the Alaska Mapping Executive Committee (AMEC) and State efforts through Alaskas Statewide Digital Mapping Initiative (SDMI) to ensure a unified approach for consistent data acquisition and enhancement of elevation data products. AMI attained interferometric synthetic aperture radar (IFSAR) data to generate Digital Elevation Models (DEMs). This radar mapping technology is an effective tool for collecting data under challenging circumstances such as cloud cover, extreme weather conditions, rugged terrain, and remote locations. Airborne IFSAR data were flown over southcentral Alaska in summer 2010 and over northwestern Alaska in 2012. Additional areas may become available as projects are inspected for quality and released for dissemination. A coverage map in EarthExplorer indicates the extent of distributable data. IFSAR Alaska Products Elevation products generated from IFSAR data include Digital Surface Model (DSM) and Digital Terrain Model (DTM) data. DSMs provide elevation values of landscape features on the earths surface. This topographic product contains the height of the highest surface on the ground including vegetation, manmade structures, and bare earth. DTMs provide elevation values of the underlying terrain of the earths surface. This topographic product reflects the height of bare earth where the elevations of vegetation and manmade features have been removed. The USGS Earth Resources Observation and Science (EROS) Center distributes IFSAR Alaska products in Georeferenced Tagged Image File Format (GeoTIFF). The pixel values for the grayscale images represent elevation numbers.