Global Mapper Pro

Problem with North direction

Geolimber
Geolimber Global Mapper User
Hi there. I am try to make georeference of my raster maps. But have problem with north direction. It shows not to the same direction as grid. Grid on the raster and grid in the GM corelate good. But north direction shows with small deviation (about 3 degres).

How i can fix this?

For example few screenshots of problem map. This map in SAD69 and UTM. But maps in WGS84 have the same problem
:(

Here you can see the big north arrow from GM schematics and grid.


01.jpg



And here you can see how thismap looks in Google Earth after export to KMZ. With this small deviation 2-3 degrees.

02.jpg

Comments

  • global_mapper
    global_mapper Administrator
    edited November 2012
    This is because Grid North and True North are not often in exactly the same direction. Your grid is in the UTM projection in which straight up is only True North at the center of the UTM zone. The further you get from the center of the UTM zone the more rotated from straight up True North will be.

    If you want True North to be straight up, switch to a projection that maintains that (at the expense of a lot of distortion) like Geographic (lat/lon) or Mercator on the Projection tab of the Configuration dialog.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • Geolimber
    Geolimber Global Mapper User
    edited November 2012
    This is because Grid North and True North are not often in exactly the same direction. Your grid is in the UTM projection in which straight up is only True North at the center of the UTM zone. The further you get from the center of the UTM zone the more rotated from straight up True North will be.

    If you want True North to be straight up, switch to a projection that maintains that (at the expense of a lot of distortion) like Geographic (lat/lon) or Mercator on the Projection tab of the Configuration dialog.

    Thanks,

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


    Thanks a lot. Good advice. I convert coordinates from map corners and made new georeference with new coordinates (in another projection), and all looks good now.
    P.S. Sorry for my bad english.
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