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USGS - science for a changing world

The National Map Seamless Server, Earth Resources Observation and Science (EROS)




General FAQ


Q. Unable to download, try any or all of these options ?

A.
  • Clear the Temporary Internet Files.
  • Make sure all popup blockers are off
  • Make sure the enable download options are checked in the internet security settings
    1. On IE go to TOOLs ---> Internet Options
    2. Click on the "Security" tab
    3. Then click the "Custom Level" button at the bottom of the page
    4. Scroll down in the resulting dialog box until you get to the section titled "Downloads"
      5. .
    5. Make sure the "Automatic Prompting for File Downloads" option is enabled
    6. Click ok
    7. Re-try the download
  • The extraction url needs to set as a trusted site, within the security settings, follow these steps
    1. On IE go to TOOLs ---> Internet Options ---> Security Tab
    2. Click on Trusted Sites (third icon in the window)
    3. Then click the SITES button. A new window should appear where you can add a website.
    4. At the bottom of the page, Uncheck the box beside --Require server ...
      5. .
    5. In the first box type in http://extract.cr.usgs.gov
    6. Click Add --- The website should appear in the second box labeled Websites
    7. Click OK
    8. Click OK

  • If still unable to download or have other problems, please email seamless@usgs.gov and provide as much of the following information as possible.
      • IP Address:
      Browser and version:
      Operating System:
      Entry URL (example http://seamless.usgs.gov or The National Map):
      URL used to download data (The National Map Seamless Server Request Summary URL):
      Date and Time of Problems;
      Error Message(s)and screenshots:
      Screen Size being used to view map:
      Another information that you might want to share as far as problem?

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Q. What can be done when the map interface or buttons do not load properly?

A. Set the screen size, within computer control panel, to a minimum of 1280 X 1024 pixels.

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Q. Are all of the reference layers listed within the map interface downloadable?

A. Not all of the reference layers are available for download. They are used just for reference.

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Q. Can quadrangles (i.e. 7.5 min) be downloaded?

A. There are templates that can be used to cut out specific size areas, like a 7.5 min quad. The template download option is under the Download Tool section on the left side of the map interface. There is a single template or multiple template options. The single template allows, from a drop down menu, for a single download. The multiple template allows a user to choose several areas and then download. As more templates are developed, they will be added to the map interface.

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Q. When new datasets are added to the interface, where are the notifications?

A. Notification of new datasets are announced on http://seamless.usgs.gov and http://gisdata.usgs.gov. New High Resolution Orthoimagery is added to the list under products.

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Q. Are there any restrictions to the data or use of the data?

A. The data from The National Map Seamless Server is public domain. There are no restrictions on data downloaded We request that the following statement be used when citing, copying, or reprinting data:

"Data available from U.S. Geological Survey, EROS Data Center, Sioux Falls, SD."

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Q. What formats are available for The National Map Seamless Server products?

A. Information about the specific datasets and formats are located under "List of Products". For quick reference see list below:
    NED 1, 1/3, 1/9 arc second data:
    ArcGrid, .BIL, GridFloat, and GeoTiff (32 bit floating point)

    NLCD 1992 and 2001 data:
    ArcGrid, .BIL, and GeoTiff with world file

    SRTM "Finished" 1 and 3 arc second data:
    ArcGrid, .BIL, GridFloat, and GeoTiff (32 bit floating point)

    High Resolution Orthoimagery data:
    GeoTiff

    BTS Roads data:
    Shapefile

    National Atlas data:
    Shapefile

    1m DOQQ's data:
    Geotiff

    MODIS DB NDVI data:
    ArcGrid, .BIL, and GeoTiff

    LP DAAC MODIS All Bands:
    ArcGrid, .BIL, and GeoTiff

    Landsat Mosaic:
    GeoTiff

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Q. What are the format descriptions?

A. ArcGrid is an Arc/Info proprietary format. Some other software packages can read the ArcGrid format. Customers who specify ArcGrid will be delivered a workspace. The workspace is not tarred or gzipped.

BIL is a non-proprietary format made by running the GRIDIMAGE command in Arc. The data is a simple binary raster format (signed integer data). There is an accompanying ASCII header file that provides file size information (number of rows and columns). The data are stored in row major order (all the data for row 1, followed by all the data for row 2, etc.).

GridFloat is a non-proprietary format made by running the GRIDFLOAT command in Arc. The 32-bit (4 byte) is a simple binary raster format (floating point data). There is an accompanying ASCII header file that provides file size information (number of rows and columns). The data are stored in row major order (all the data for row 1, followed by all the data for row 2, etc.). More information about binary floating point is at:


Geotiff (32 bit floating point) is a 32 bit floating point grid format. More information on the 32 bit floating point TIFF is at: http://partners.adobe.com/asn/developer/graphics/graphics.html

Geotiff with world file is a non-proprietary format. It is essentially a floating-point binary data file with accompanying ASCII descriptor files including a world file containing geographic extents for the file.

Geotiff are georeferenced .tif file and includes a projection file and world file.

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Q. What is the byte order for the .BIL format?

A. A. The DEM header file is an ASCII text file containing size and coordinate information for the DEM. The data are stored in row major order (all the data for row 1, followed by all the data for row 2, etc. ). The following keywords are used in the header file:
    BYTEORDER byte order in which image pixel values are stored
      I = Intel byte order (most significant byte first)
    LAYOUT - organization of the bands in the file
      BIL = band interleaved by line (note: the DEM is a single band image)
    NROWS - number of rows in the image
    NCOLS - number of columns in the image
    NBANDS - number of spectral bands in the image (1 for a DEM)
    NBITS - number of bits per pixel (16 for a DEM)
    BANDROWBYTES - number of bytes per band per row (twice the number of columns for a 16-bit DEM)
    TOTALROWBYTES - total number of bytes of data per row (twice the number of columns for a single band 16-bit DEM)
    BANDGAPBYTES - the number of bytes between bands in a BSQ format image (0 for a DEM)


    Example header file
      BYTEORDER --- I
      LAYOUT --- BIL
      NROWS --- 2764
      NCOLS --- 4836
      NBANDS --- 1
      NBITS --- 16
      BANDROWBYTES --- 9672
      TOTALROWBYTES --- 9672
      BANDGAPBYTES --- 0
More Information on BYTEORDER refer to and their related links for an explanation of what is affected by BYTEORDER. Or refer to http://www.ncsu.edu/it/sas/help/lrcon/z0920443.htm for an example explaining the handling of signs in various BYTEORDERs

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Q. The default format is ArcGrid. Where can the format be modified?

A. The Data Format, Archive Format, and Metadata Format can be changed from The National Map Seamless Server Request Summary Page. At The National Map Seamless Server Request Summary Page, click on "Modify Data Request". Then use the drop down menus next to each product to make the changes. Scroll to the bottom of the page and Save Changes.

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Q. Can a projection be specified when downloading?

A. The projection for most of the data is Geographic (latitude and longitude), unless otherwise specified. There is not an option to user specify projection.

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Q. Is there a tutorial explaining how to download?

A. Yes, there is a tutorial explaining how to download data. The tutorial is a .PDF file located under "Background" on the front page of The National Map Seamless Server.

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Q. When downloading, the window that gives the option to save data does not appear?

A. The windows may be considered pop ups by your system. Turn off any pop up blocker software.

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URL: http://seamless.usgs.gov/faq/general_faq.php
Page Contact Information: webmapping@usgs.gov
Page Last Modified: November 22, 2007