Lambert 72 projection parameters

jrr
jrr Global Mapper User
edited October 2012 in Bug Report
I have a problem when reading shapefiles I saved in ArcMap with Lambert72 projection.

There is a shift in the data. I will attach the screen and two projection files. (ESRI and GM)
I never had this problem with earlier versions of the software.

Thanks in advance,
Jürgen

Comments

  • global_mapper
    global_mapper Administrator
    edited September 2012
    What application are you seeing the shift in and what version of Global Mapper are you using? I don't see any difference in the PRJ definitions other than some centimeter-level differences in parameters and a difference name for the same datum.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • jrr
    jrr Global Mapper User
    edited September 2012
    I am using version 13.2.
    The shift appears in Global Mapper. It is as if the .prj file from ArcGis messes things up.
    When I load the data without using the ArcGis prj file and select Lambert72 projection within Global Mapper it overlays correct.

    Jurgen
  • jrr
    jrr Global Mapper User
    edited September 2012
    Mike,

    I tried to change the Datum name from "D_Belge_1972" to "D_BD72" (the one used by GM) and it overlays correctly.
    So I guess it is a name recognition problem ?
  • global_mapper
    global_mapper Administrator
    edited September 2012
    Ah yes, the datum name used by ArcGis simply wasn't recognized by Global Mapper. I'll add that name to new GM builds so ArcGis-PRJ files can be recognized.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • jrr
    jrr Global Mapper User
    edited October 2012
    Hi Mike,

    I updated to v14(64bit) and the latest build (b100512)
    It did not solve the problem, it made matters worse. The shift is even bigger now.
    In earlier versions of GM everything worked fine.
    Thanks,
    Jürgen
    BD72.jpg 680.1K
  • global_mapper
    global_mapper Administrator
    edited October 2012
    Can you provide the data file that you are trying to load that is offset? The parameters all look fine and the BD72 datum shift parameters used in Global Mapper seem to agree with what georepository.org lists as the best transformation parameters. Also those datum shift parameters shouldn't have changed.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • jrr
    jrr Global Mapper User
    edited October 2012
    Hi Mike,

    I attached the data.
    There is one weird thing I noticed :
    When I change the 'Datum' in the Projection tab from the loaded data to 'D_BELGE_1972' it shifts of course, but after changing it back to it's original 'BD72 (BELGIUM 1972)' the data shifts to the correct Lambert72 position.

    Jürgen
  • global_mapper
    global_mapper Administrator
    edited October 2012
    Oh wow I found the problem. In my recent change I had a typo and was assigning completely the wrong datum for the file. However another quirk on the projection dialog due to the Belge 1972 projection only listing a few supported datums made that error invisible so it looked like the proper datum was used, but it really wasn't! I've fixed that now and the data properly overlays. I have placed a new build at http://www.globalmapper.com/global_mapper14.zip with the latest changes for you to try. Simply download that file and extract the contents into your existing v14.xx installation folder to give it a try. If you are using the 64-bit v14 version there is a new build at http://www.globalmapper.com/global_mapper14_64bit.zip .

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com

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