Elevation
Elevation is the most foundational spatial dataset. Other layers, such as imagery, are draped over elevation to provide three-dimensional models of the earth's surface. Elsewhere in the United States, elevation is being acquired at 1-meter resolution, often repeatedly to show changes over time. In Alaska many areas are only mapped to 60-meter resolution elevation data. This results in enormous errors and inaccuracies, which has proven fatal to pilots relying on accurate information to safely navigate in low visibility conditions. A technology known as IfSAR is being used to collect improved elevation data in Alaska at a 5-meter resolution.
Alaska's IfSAR elevation dataset is now 60% complete, allowing for detailed 3-dimensional modeling of mountain ranges, drainage basins, and even glaciers. IfSAR stands for interferometric synthetic aperture radar, and is also referred to as InSAR. Radar pulses are used to measure surface (tree tops) and bare earth elevations. Another product of IfSAR are images of the radar returns called orthorectified radar images, or ORIs, which are used for mapping soils and geology.
At this time there are no defined acquisition plans for the 2016 collection season. The Alaska Governor's Office has placed a high priority on completing the Arctic. Alaska is the only Arctic state in the United States.
Challenges to planning include the patchwork nature of land ownership, disparate priorities specific to confined areas of interest and a lack of unspecified funding to fill gaps between targeted areas of interest for which specific needs funding exist.
Voluntary funding sources derived from Federal land owners are confined explicitly to their respective land holdings. Often times these funding sources don't align with efficient flight logistics because the targeted areas are at opposite ends of Alaska, and this can be challenging.
There is no known calculus that can resolve this, except to try and preserve funding to the best of our cooperative ability and cobble it together, filling gaps in coverage with additional funding partners and/or unspecified funding where available. Congressionally directed funds to complete this project would be very helpful in resolving this calculus. The goal is to collect elevation data for the remainder of Alaska in two to three collection years (2015 - 2017). Elevation data has a shelf life in excess of 20 years. Approximately 53% of the State has been collected and has been delivered or is in processing. Anticipated delivery dates for recently acquired IFSAR can be found on the IFSAR delivery status map below.
Elevation Data Modernization Progress To Date
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.
Efforts to complete coverage for the remainder of the State began in earnest after the 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%.
The resulting elevation data are licensed in the public domain and available to all users through the Internet. The deliverables include digital elevation data of the "bare earth" and a digital surface model of the vegetation, buildings, and other objects on the surface and ortho-rectified radar images.
State and Federal agencies funded these 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. To date, $28.89M has been spent on modernizing the elevation data for Alaska in a State and Federal partnership. Of this Federal partners have provided $19.19M or 67% of the acquisition cost. It is imperative the State of Alaska maintain its good faith effort to fund this effort in order to maintain momentum and preserve partnerships. For more information regarding funding and partnerships please visit the "Funding" page. The AGC, DNR and the Department of Interior lead the State and Federal collaborative effort to acquire digital elevation data.
