BACKGROUNDER
Mapping Alaska—America’s Last Frontier
Fairfax, VA—September 2015
USGS and SDMI IFSAR Mapping of Alaska
The Alaska Statewide Digital Mapping Initiative (SDMI) seeks to
provide an accurate, seamless, statewide base map, available
over the internet, through open standards, and free of charge.
The target basemap is a statewide ortho-image, controlled by
an appropriately scaled elevation model and ground control as
required. SDMI has long recognized that the U.S. Geological
Survey (USGS) topographic quadrangles of Alaska were the
agency’s only such maps in the U.S. that had never met
National Map Accuracy Standards. Until new mapping under
SDMI began in 2010, the state’s maps had not been updated
since the 1950s.
The National Map
Because hardcopy maps, such as those used in Alaska, were
impossible to maintain nationwide, USGS devised The National
Map, a collaborative effort among USGS and other federal,
state, and local partners to improve and deliver topographic
information for the nation. These US Topo maps consist of
digital orthophoto base maps linked to other layers such as
elevation, hydrography, transportation, place names, and
administrative boundaries. Each map layer can be updated
digitally as changes are made. Available free to the public, the
US Topo layers can be turned on or off for viewing and printing
as GeoPDF documents using Adobe Reader or comparable
viewing software.
Approximately 54% of Alaska (dark green areas) has been funded and
mapped; an additional 4.1% (light green) has been funded for data
acquisition only. The Dewberry team acquired an additional 8.7% (pink) on
speculation in order to acquire the data in efficient acquisition blocks, saving
money for the government, once funded. The remaining 33% (tan) has not
yet been acquired.
”My career in mapping has
spanned more than 50 years,
and it appears I may have saved
the best for last. I have
appreciated the opportunity to
work with the strong coalition of
agency representatives involved
in the Alaska Statewide Digital
Mapping Initiative and look
forward to completing this vital
effort to bring high-quality map
images to the many citizens and
professionals who rely on them
every day. Alaskans will be well
served by the updated data with
its many applications today and
for the future.
In a sense, this has been my
own summit to climb, and we’re
still on the journey. It has been a
great honor to help map
‘America’s Last Frontier.’”
Dr. David Maune
Senior Project Manager
Dewberry
A Comprehensive Solution
Alaska was the only state that did not have statewide digital
orthophotos, for two primary reasons: (1) persistent clouds on
aerial or satellite imagery, and (2) lack of a digital elevation
model (DEM) accurate enough for digital orthorectification,
which corrects for perspective view image displacements
caused by rugged terrain. Without current topographic maps or
digital orthophotos, it is extremely difficult for federal, state, and
local governments; universities; and private users to manage
Alaska’s vast natural resources and infrastructure. Furthermore,
the state has experienced a high number of Controlled Flight
into Terrain (CFIT) aviation accidents. The old topographic
quad maps were believed to depict mountains hundreds of
meters from their actual locations, and in some locations,
ridgelines had never been mapped at all.
Alaska SDMI authorities and mapping experts struggled for
years to determine a comprehensive solution. In 2008, Dave
Maune, Ph.D., of Dewberry, attended a workshop in Alaska to
brief SDMI members on the importance of DEMs. Maune and
Dewberry subsequently authored a study, the Alaska DEM
White Paper, which offered recommendations to resolve the
challenge of obtaining DEMs suitable for production of
statewide US Topo maps.
Central to the study’s recommendations was the proposal that
USGS and the state rely on Interferometric Synthetic Aperture
Radar (IFSAR) technology to obtain mid-accuracy DEMs and
Ortho-rectified Radar Imagery. This technology had the benefits
of mapping through clouds, fog, smoke, and haze. In 2010, as
part of Dewberry’s Geospatial Products and Services contract
(GPSC), USGS authorized the Dewberry team, including
Intermap Technologies and Fugro EarthData, to begin mapping
the state with IFSAR, subject to the availability of funds.
As of August 1, 2015, as shown on the map above in dark
green, 54.2% of the state (319,000 mi2) has been funded and
mapped; an extra 4.1% (light green) has been funded for data
acquisition only; and the Dewberry team acquired an additional
8.7% (pink) on speculation in order to acquire the data in
efficient acquisition blocks to save money for the government,
once funded. The remaining 33% (tan) has not yet been
acquired. As of August 31, more than half of the pink cells
acquired on speculation going back to 2010, has been funded.
Denali
In a related task order completed for USGS together with the
National Oceanic and Atmospheric Administration’s National
Geodetic Survey (NGS), Dewberry recently assembled a
survey team to address the unique challenge of mapping the
elevation of Denali (formerly Mount McKinley) in Denali
National Park. Since 1953, when surveyed with trigonometric
leveling, the mountain’s summit elevation had been recorded as
20,320 feet, the highest point in North America. The IFSAR
DEM had indicated a lower elevation, but Dewberry recognized
that IFSAR’s mid-accuracy DEM with 5-meter elevation point
spacing—although optimal for statewide mapping of remote
areas—was not the best technology for establishing an
authoritative elevation for Denali because of steep slope
conditions and a pointy snow-covered peak, and should not be
considered authoritative. Dr. Maune and the Dewberry team
Blaine Horner, survey party chief with
CompassData, a Dewberry subcontractor, was
part of the four-man survey team to reach the
summit of Denali on June 24. He is shown here
at the summit with two GPS antennae.
recommended a GPS survey, which required a survey team to
climb to the summit and set up and operate GPS equipment
under extreme conditions. USGS and NGS funding was
received in early June 2015 for this effort.
CompassData, another Dewberry GPSC subcontractor, quickly
mobilized a team of three experienced climbers/surveyors and
were joined by a scientist from the University of AlaskaFairbanks Geophysical Institute. Their expedition was
conducted between June 15th and 30th. Commercial partners
also included Mountain Trip, Trimble, CompassCom,
CompassTools, and DeLorme. Carrying about 600 pounds of
equipment—80 pounds of which was survey equipment
including two GPS receivers and ground penetrating radar—the
survey team reached the summit on June 24th. Following
several weeks of data analysis, a new elevation of 20,310 feet
was recorded for Denali and announced by USGS on
September 2. This was the elevation of the top of the snow on
June 25th, and a CompassData probe measured the depth of
the snow to be 4.15 meters at which point resistance was met
from either rock or ice. It was impossible to establish a normal
survey monument anchored in rock, so even this new elevation
is not truly authoritative in the eyes of NGS. Although slightly
lower than the 1953 survey, the new elevation will remain a
source of pride for Alaskans who cherish their sacred mountain.
About Dewberry
Dewberry is a leading, market-facing firm with a proven history
of providing professional services to a wide variety of publicand private-sector clients. Recognized for combining
unsurpassed commitment to client service with deep subject
matter expertise, Dewberry is dedicated to solving clients’ most
complex challenges and transforming their communities.
Established in 1956, Dewberry is headquartered in Fairfax,
Virginia, with more than 40 locations and 2,000+ professionals
nationwide. To learn more, visit www.dewberry.com.
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Related Links:
Dewberry
www.dewberry.com
No Time to Lose: Mapping the State
of Alaska
http://www.dewberry.com/news/blog/p
ost/blog/2014/04/03/no-time-to-losemapping-the-state-of-alaska
Media Contact:
Molly Wagner
703.849.0307
[email protected]