archived DOQ geotiff

Riverbum1850Riverbum1850 Global Mapper UserPosts: 11Trusted User
edited March 2015 in Raster Data
I downloaded a DOQ geotiff from EarthExplorer when i try to open it in GM13 it states "reading of archived data is nor supported. Please un-archive and try again" How do I un-archive? When I try to extract there is nothing to extract. What Am I missing?


  • MykleMykle Global Mapper User Posts: 452Trusted User
    edited February 2015
    Files downloaded from USGS are likely to be packaged by a UNIX method that is good to remember.
    This method goes back before ZIP was invented, before Graphical User Interfaces (GUI) like Windows were invented, so you did your work by typing at a command prompt.

    So, to package files you had to convert binary files to a text file using a method that could be extracted reliably on the other end, after the file was transferred through a variety of servers running different operating systems. The files are larger after this step. (TAR)

    Then you could combine your files into a compressed file, and this is the file (TGZ) that you would send (using FTP !!). Extracting the files was a two-step process.

    Today, some ZIP programs (I'm using 7ZIP) can extract files from a TGZ. Unwrap your downloaded file far enough and you will find a TIF and HDR file that Global Mapper will load.

    One of my downloaded files did not include a filename extension, and I haven't had time to figure out what needs to be done. Others were TGZ files.

    Global Mapper can open and use files within a ZIP file, but not a TGZ (perhaps some flavors are acceptable).

    I downloaded a DOQ from Earth Explorer, removed the packaging, and loaded the TIF without problems.

  • Riverbum1850Riverbum1850 Global Mapper User Posts: 11Trusted User
    edited February 2015
    Thank You Very Much 7zip did the job
  • brightstarbrightstar Global Mapper User Posts: 1
    edited March 2015
    Hmm...thanks for the nice sharing keep it up
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