Possible to use ESRI aux.xlm file image rectification points in Global Mapper?

bisenbergerbisenberger Global Mapper UserPosts: 53Trusted User
edited June 2014 in Technical Support
I have attached is an ESRI aux.xlm file containing SourceGCPs and TargetGCPs. Would it be possible to load and or rectify the image using this info in Global Mapper?

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited June 2014
    Global Mapper should already look for an .aux.xml file with a raster image when loading it if it couldn't find other position information. The SourceGCPs and TargetGCPs should be used to create a rectification, along with the projection defined in the file. Do you have a sample file where this isn't happening?

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • bisenbergerbisenberger Global Mapper User Posts: 53Trusted User
    edited June 2014
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited June 2014
    Ah I see the issue. We didn't have a .aux.xml with both a <SRS> and <WKT>. Since they are the same it is fine. I've fixed the importer to use this file. I have placed new builds with the latest changes at the links below:

    32-bit: http://www.bluemarblegeo.com/downloads/global-mapper/global_mapper15.zip
    64-bit: http://www.bluemarblegeo.com/downloads/global-mapper/global_mapper15_64bit.zip

    Simply download the .zip file for the build that you are using and extract over your existing installation files. The likely locations to extract to are as follows:

    32-bit: C:\Program Files (x86)\GlobalMapper15
    64-bit: C:\Program Files\GlobalMapper15_64bit

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • MykleMykle Global Mapper User Posts: 392Trusted User
    edited June 2014
    Global Mapper v15.2.3 (b060514) [64-bit] [+GEM] - REGISTERED

    Mike,
    When I open his sample file with the new build, it is positioned on the EQUATOR at 97W.

    I manually rectified the image yesterday as a test, using the <SourceGCPs> and <TargetGCPs> values, and these values are good and overlay USAtopo coverage nicely.

    The only issue was working out that the <SourceGCPs> reference the lower left corner of the image, not the usual upper left. Probably an ESRI thing that you already know about :-)

    I frequently have similar issues with DXF winding up on the equator, but probably not for the same reasons.

    Thanks,
    Mykle
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited June 2014
    Mykle,

    Ah I just fixed the projection issue, I hadn't noticed that the control points were also wrong. Every other .aux.xml that I've seen oddly used inches from the bottom left (based on image DPI) for the <SourceGCPs>, and this TIFF had no DPI, so the GCPs were ignored and the control points in the TIFF file header used. In this case the <SourceGCPs> are actually pixel coordinates (again from the bottom left instead of top left with Y increasing down as is typical). I can find nothing in the .aux.xml header that specifies whether the source coordinates are inches (a very odd choice) or pixels (makes more sense), but I was able to add some logic to guess this automatically which should work for all but an extremely strange case of a very low DPI (i.e. DPI of 1 or 2) image.

    I have placed new builds with the latest changes at the links below:

    32-bit: http://www.bluemarblegeo.com/downloads/global-mapper/global_mapper15.zip
    64-bit: http://www.bluemarblegeo.com/downloads/global-mapper/global_mapper15_64bit.zip

    Simply download the .zip file for the build that you are using and extract over your existing installation files. The likely locations to extract to are as follows:

    32-bit: C:\Program Files (x86)\GlobalMapper15
    64-bit: C:\Program Files\GlobalMapper15_64bit

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • MykleMykle Global Mapper User Posts: 392Trusted User
    edited June 2014
    Global Mapper v15.2.3 (b060614) [64-bit] [+GEM] - REGISTERED

    Mike,
    Same issue:
    When I open his sample file with the new build, it is positioned on the EQUATOR at 97W.

    Did I download the update too soon ;-) ?

    I do have the tif and tif.aux.xml in the same folder (Downloads).

    If I do NOT have the tif.aux.xml in the same folder, a Select Projection dialog appears, with the appropriate default settings.
    If the file IS present, the dialog does not appear. In both cases, the bottom edge of the image is on the equator.
    Mykle
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited June 2014
    Mykle,

    It's possible you got the update too soon if you downloaded within 2 minutes of my post as I posted before the upload finished :) However that seems unlikely.

    The .aux.xml will only be used instead of the built-in position information right in the TIFF header if you have the option checked at the top of the Advanced section of the General tab of the Configuration dialog to prefer the TFW world file. This will really prefer any position metadata file over the built-in coordinate information in the GeoTIFF header. By default GM prefers the information right in the file header (if present) rather than any external files.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • MykleMykle Global Mapper User Posts: 392Trusted User
    edited June 2014
    There are reasons why you are the Guru. The Config setting needed to be set, apparently due to the TIFF tags being incomplete or incorrect. Now it loads correctly and overlays the USAtopo nicely.

    Now we'll see how it works for bisenberger

    Thanks,
    Mykle
  • bisenbergerbisenberger Global Mapper User Posts: 53Trusted User
    edited June 2014
    Sorry, had to do a bunch of running around today. Downloading now... will report how it works here in a bit.
  • bisenbergerbisenberger Global Mapper User Posts: 53Trusted User
    edited June 2014
    Bingo! Thanks Mike, much appreciated.
    Bill
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