Elevation is the most foundational spatial dataset. Many other spatial datasets, such as hydrography and topographic maps, are based on elevation data. Elevation data is also a fundamental component of any three-dimensional models of the earth's surface. Until recently, quality elevation data over much of Alaska has been lacking. Many areas of the State were only covered by outdated 60-meter resolution elevation data. This resulted in enormous errors and inaccuracies, which has proven fatal to pilots relying on accurate information to safely navigate in low visibility conditions. The USGS's 3D Elevation programs (3DEP) goal is to acquire complete high resolution elevation coverage by 2023. In most of the country lidar data is the basis for this elevation data. However in Alaska, because of remoteness and size, a technology known as IfSAR is being used as part of the Alaska Mapping Initiative to collect foundational elevation data at a 5-meter resolution. State and Federal agencies fund the IFSAR acquisitions; Federal contributors include the US Geological Survey, National Geospatial Intelligence Agency, US Forrest Service, US Dept of Agriculture/National Resource Conservation Service, US Park Service and the Bureau of Land Management. Alaska's IfSAR elevation dataset is nearing completion, allowing for detailed 3-dimensional modeling of mountain ranges, drainage basins, and even glaciers.
To view and/or download the State's elevation data, visit the Alaska Elevation Portal.
IfSAR stands for interferometric synthetic aperture radar, somethimes also referred to as InSAR. Radar pulses are used to measure both the reflective surface, such as tree tops (DSM - digital surface model) and bare earth elevations (DTM - digital terrain model). Another product of IfSAR are images of the radar returns called orthorectified radar images, or ORIs, which are used for mapping soils and geology. The resulting elevation data are licensed in the public domain and available to all users through the Internet.Alaska IFSAR Data and Status Web App
High Resolution Elevation Data: lidar & sfm
The quantity and quality of high resolution elevation data for Alaska, primarily collected with lidar and structure for motion (sfm) technologies, continues to increase. Elevation data has historically been acquired exclusively by contracted data collectors. Increasingly, however, more organizations are collecting project specific elevation data in house with drone or other technologies. The USGS publishes standards and specifications to ensure interoperability of elevation data across collections with a goal towards a nationally consistent dataset.
To view the status and metadata of both existing and in production elevation datasets in Alaska visit the Alaska Elevation Status Web App. To submit planned, in-production, or existing elevation dataset to the portal email the Alaska Elevation Program group.Alaska Elevation Status Web App
Alaska Elevation Data Modernization History
Elevation data modernizations for Alaska started in the early 2000's, when the Bureau of Land Management and the U.S. Geological Survey (USGS) collected IfSAR over the National Petroleum Reserve in northern Alaska. See the Alaska IFSAR Data and Status Web App to view the coverage of all legacy IfSAR data. In 2008 an Alaska DEM Workshop was held in Anchorage. The outcome of this workshop was the generation of a whitepaper title, Digital Elevation Model (DEM) Data for the Alaska Statewide Digital Mapping Initiative (SDMI). This whitepaper identified statewide requirements and alternative solutions for obtaining accurate and current digital elevation data for Alaska.
Efforts to begin systematic collection of IfSAR of the entire State began in earnest after the Alaska Statewide Digital Mapping Initiative (SDMI) adopted the stakeholder driven IfSAR requirement. In 2010, the State of Alaska and the USGS consolidated State and Federal funds to contract with Dewberry Engineering for the acquisition of 157,434 square kilometers in south-central Alaska. A follow-on 2011 project added 28,113 square kilometers of coverage in the same area. In 2012 and 2013, attention shifted to northwestern Alaska and the Arctic, where project participants contracted for 226,757 square kilometers of coverage in 2012 and 159,056 square kilometers in 2013 bringing total statewide completion to 43.7%. As of 2019 the IfSAR data collection is nearing completion.
Alaska Elevation in the News
- Mapping Alaska with IFSAR - xyHt
- New elevation maps detail Alaska like never before
- Alaska Has Finally Been Mapped as Precisely as Mars