Re-projection

ic3wallic3wall Global Mapper UserPosts: 16
edited January 2015 in Projection Questions
Hi,

I have two maps of the same site, one is a .xyz topo file and one is a projection .zip file contaigning many attributes. I'm interested in only one of the attributes, so I created an elevation grid with it for this attribute. XY coordinates of the topo and the newly created grid are different, how can I make the latter in the same xy coordinate system as the topo map ?

I played with the projections but no success ...

Thanks

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited January 2013
    What projection are the coordinates in the .zip file in? So long as you select the correct projection for the data when prompted at load time Global Mapper should automatically convert them so they will line up properly.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.bluemarblegeo.com/
  • ic3wallic3wall Global Mapper User Posts: 16
    edited January 2013
    I do chose the same projection when I load the xyz topo as the .zip file, but coords still don't match

    Coords in .zip are quebec_mtm

    Ho and by the way, I have another question concerning the grid elevation I produced with my attribute. Sometimes, the attributes contains no value, so GM does an interpolation with adjacent data, how can I prevent this ?
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited January 2013
    Choosing the same projection is only correct if the coordinates in both files are actually in the same projection system. If one is Quebec MTM and the other lat/lon (for example), you have to choose the correct projection system for each file. Then Global Mapper will reproject as necessary to make them line up. Do you know the projection system for the XYZ file?

    If you add a valid value for your attribute (search for those that have an empty value and edit them) you can prevent assignment. At least if I'm understanding what you want correctly.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.bluemarblegeo.com/
  • ic3wallic3wall Global Mapper User Posts: 16
    edited January 2013
    Choosing the same projection is only correct if the coordinates in both files are actually in the same projection system. If one is Quebec MTM and the other lat/lon (for example), you have to choose the correct projection system for each file. Then Global Mapper will reproject as necessary to make them line up. Do you know the projection system for the XYZ file?

    If you add a valid value for your attribute (search for those that have an empty value and edit them) you can prevent assignment. At least if I'm understanding what you want correctly.

    Thanks,

    Thank you, I solved the projection problem. I'm still struggling with the other issue. I did what you said and replaced all empty field by a certain value. When I create elevation grid, it still interpolates. I don't want any interpolation. Can I select a 'nearest integer option' when creating the grid?
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited January 2013
    You can turn off resampling for the grid layer on the Options dialog for the layer, accessible from the Control Center. Just set it to 'Nearest Neighbor' to turn off the resampling that is bilinear by default for grid layers.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.bluemarblegeo.com/
  • magneticnorthmagneticnorth Global Mapper User Posts: 3
    edited September 2013
    I have a dwg file that came in with no projection. I am trying to align it with survey controls (with xy values) or transform it. Which tool(s) should I use?

    Brian
    Magnetic North
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited September 2013
    Brian,

    After loading the DWG you can right-click on it in the Control Center and choose to Reposition it (rectify like imagery) or Shift/Transform the coordinates to get it to match up with other data.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • magneticnorthmagneticnorth Global Mapper User Posts: 3
    edited January 2015
    Mike,

    I have an ECW file with State Plane, Colorado Central, US Survey Feet. I am trying to convert to UTM, WGS84 and meters. Can you step me through the process? Am I configuring first, then exporting? Or should I be doing a batch conversion, reprojection? I've tried several different ways. I am trying to create a background image for OCAD. Thanks Brian
  • MykleMykle Global Mapper User Posts: 442Trusted User
    edited January 2015
    Brian,
    Import your ECW by specifying the state plane coordinates.
    Then use configure/projection to switch to UTM.
    Ensure that the units get changed to meters, as they are likely to remain in feet.
    Turn on the grid if you like.

    Cheers,
    another Mike
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