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Alaska Mapping Initiative: Frequently Asked Questions


Why is the USGS updating digital map data and making new maps of Alaska?
Alaska is the only State that does not have current digital statewide map coverage at a scale comparable to the rest of the United States. The majority of the USGS topographic maps of Alaska in the current collection are 40 to 50 years old. New digital maps created at a larger scale using updated digital source data will be a
great benefit to many map users in Alaska.


What are some of the challenges of mapping Alaska?
The State of Alaska poses unique barriers to mapping. Its large physical extent, vast roadless areas accessible only by air, severe climate, and volcanic activity and wildfires all contribute to complicating the mapping effort. Recently, the USGS National Geospatial Program (NGP) committed to developing a program, the Alaska Mapping Initiative, that will bring Alaska digital geographic information and map quality and timeliness up to the level of the other 49 States.


What makes it possible to map Alaska now?
Advances in technology make it possible to create
digital map data and map Alaska with greater efficiency and increased automation than in the past. High-resolution satellite imagery is being made available statewide. Airborne radar technology is being used to acquire new 5-meter elevation data to replace 60-meter elevation data. Digital surface-water mapping (hydrography), boundaries, names, structures, and roads data layers are being made available from multiple State, Federal and commercial sources to incorporate into the maps. Additionally, State and Federal partners, through the Alaska Statewide Digital Mapping Initiative and the Alaska Mapping Executive Committee, have committed resources toward making Alaska mapping updates a reality.


What is the Alaska Mapping Initiative (AMI)?
The
Alaska Mapping Initiative (AMI) is a USGS initiative to focus resources and partnerships to update Alaska digital map data and create US Topo maps over Alaska. The AMI works with the Alaska Mapping Executive Committee and the Alaska Statewide Digital Mapping Initiative to accomplish these goals.


What is the Alaska Mapping Executive Committee (AMEC) and how does it relate to the Alaska Statewide Digital Mapping Initiative (SDMI)?
The
AMEC is a Federal coordinating committee with State representation. Fifteen Federal agencies and numerous other Federal entities are represented on the Committee. Alaska's Lt. Governor and representatives from various Alaska Departments are members of the AMEC. SDMI is an Alaska cooperative program made up of Alaska State entities focused on acquiring new and better map data for the State as a whole, including elevation and imagery base data. The two initiatives work collaboratively to reduce duplication of effort and prioritize mapping activities across State and Federal missions.


What is the difference between the US Topo Program and the Alaska Mapping Initiative?
The Alaska Mapping Initiative encompasses acquisition and enhancement of all of the digital base layers managed by the USGS National Geospatial Program (NGP) over Alaska. NGP is working in cooperation with multiple State and Federal agencies to improve the accuracy and availability of new map data. US Topo is a derivative product that can be generated using the new digital data layers maintained by the USGS in The National Map databases. The USGS integrates data from multiple sources to create the digital maps. Topos provide users with pre-packaged, symbolized digital maps of the data over a standardized grid of map cells that are easy to download and view. These maps will be improved as underlying base layers are improved through new data acquisition and updating by the USGS and by partnering agencies.


Will the Alaska Topos look the same as the conterminous United States US Topo maps?
In addressing base mapping requirements in Alaska, the map layers and other design characteristics will mirror, to the greatest extent practical, the design of conterminous
US Topos. Metadata and map collar content will follow the same principles. The datum remains NAD83/WGS84 with the Transverse Mercator Projection and Universal Transverse Mercator (UTM) parameters. The USGS will use 5-meter interferometric synthetic aperture radar (ifsar) or equivalent data as the source for contours and shaded relief. Imagery underlying the Alaska US Topo maps will be SPOT-5 satellite imagery acquired by the State of Alaska.


What scale is Alaska being mapped?
US Topo maps of Alaska will be created at 1:25,000 map scale. The decision to map at this scale is based on strong user feedback requesting larger scale maps statewide over Alaska than had been produced by the USGS in the past. 1:25,000-scale maps also have particular advantages in supporting science and military applications.


Where can I get US Topo maps for Alaska?
US Topo maps are accessible for free download from
The National Map Viewer and for download and order from the USGS Store Map Locator & Downloader. The maps will be available as they are produced and posted over the next few years. Instructions for downloading maps from the USGS Store are available in the US Topo Map and Historical Topographic Map Users Guide.


What is the current coverage of US Topo maps in my area?
Availability of US Topo maps can be viewed at
The National Map Viewer and the USGS Store Map Locator & Downloader. The maps will be available as they are produced and posted over the next few years. Instructions for downloading maps from the USGS Store are available in the US Topo Map and Historical Topographic Map Users Guide.


How will printed US Topo map copies be made available to the public?
Printed copies can be ordered at the
USGS Store or by calling 1-888-275-8747 (1-888-ASK-USGS) option 1. Major credit cards are accepted. Each map is $15.00 and a $5 handling fee is applied to all orders. Users can print the maps, in their entirety or in customized sections, on a wide variety of plotting devices.


What are the data sources for the Alaska US Topo projects?
The USGS will use
digital data provided by multiple agencies to produce the US Topo maps over Alaska.


Where can I get Alaska digital map data?
Alaska digital map data used on the US Topo products is available for download from The National Map website:
http://nationalmap.gov/, with the exception of roads and imagery data which are not publicly licensed. Additionally, imagery web map services of the SPOT-5 data are available from the Alaska Mapped website: http://www.alaskamapped.org/.


Are there restrictions on the use of the Alaska digital map data?
All data used on the maps are in the public domain except the commercial roads data and the satellite imagery provided by the State of Alaska. The USGS does request that the following statement be used when copying or reprinting data: "Data available from the U.S. Geological Survey."


Are metadata available for the US Topo maps?
Federal Geographic Data Committee (FGDC) compliant metadata will accompany each map.


Where can the particular map symbology for the US Topo maps be found?
The latest symbology used for this series can be found at:
http://nationalmap.gov/ustopo/images/US_Topo_Map_Symbols.pdf.


What historical topographic maps for Alaska are available?
The primary series for Alaska during the original topographic mapping program published in the 1950s and 1960s were created at 1:63,360-scale, or one inch to the mile. Map revisions started in the 1970s and extended into the 1990s. The cell sizes are 15 feet in latitude (height), but vary in longitude (width). There are four different widths (20', 22.5', 30', and 36'). There are about 3,000 standard cells, but because of overlapping off-grid and irregular cells, not all standard cells have a published map. About 250 1:25,000-scale quadrangles were also published, mostly over urban areas and national parks, in the 1970s and 1980s. The following table shows the number of the topographic quadrangles available in digital format for Alaska. Many other specialty maps in Alaska have also been published.

Count
 
Description
 
2,505
 
63K topo map
 
612
 
63K orthophotoquad
 
259
 
25K topo map
 
152
 
250K topo map
 
14
 
250K shaded relief
 
8
 
250K topo/bathy
 
11
 
specialty maps at various scales
 


Where can I get historical topographic maps for Alaska?
Currently, Alaska historical maps in GeoPDF file format are available to download free of charge from the
USGS Store. Instructions for downloading maps from the USGS Store are available in the US Topo Map and Historical Topographic Map Users Guide.


Why do contour lines extend into open water on some US Topo maps?
Traditional topographic maps (maps published before about 2000) derived hydrography and hypsography from a single data source, usually the same aerial photographs. In addition, the maps were drafted by hand, which allowed precise visual integration of different feature classes. On traditional topographic maps, non-bathymetric contour lines in open water were considered errors.

US Topo maps, the new digital product produced since 2000, are mass-produced from national GIS databases. Different data layers come from different sources collected at different times. The ortho image, the elevation data, and the water data from these databases will usually not represent the same point in time at any particular spot. Water levels rise and fall, meandering stream channels shift, so water extents and elevation data collected at different times will often not match exactly. The problem is exacerbated if one or both data layers are relatively old or from low-resolution sources, or if extreme seasonal or climate variations have occurred between data collection dates.

In Alaska, where contours are generated from recent lidar (light detection and ranging) or ifsar (radar) elevation data, the older hydrography data is updated to reflect very major stream course or water body changes. However, minor changes and differences due to fluctuating seasonal or annual climate variations are not reflected in the hydrography data. These source differences can result in contours intersecting water features. Such occurrences are common where lidar or ifsar sensors detect stream banks and shoals during low-water conditions and, therefore, are allowed to remain in the US Topo to allow the user to visually see the ground surface based on the newly collected elevation source.




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Page Last Modified: Friday, 06-Dec-2013 13:01:58 EST