XYZ Grid Reprojection: NAD27 to UTM13N

Hi everyone,

I apologize if this question is a repeat of another, but I'm very new to Global Mapper and can't seem to find the right post that addresses the reprojection process that I need to follow. I'm running v19.1.

I received an XYZ text file from a client in the Colorado North 501 NAD27 coordinate system, but the files that our company uses internally are of the UTM13N coordinate system. How can I reproject the client's original file to our internal coordinate system and export the resulting file to an XYZ or LAS file? 

Thanks for your help!

Best Answer

  • MykleMykle Global Mapper User Posts: 442
    Answer ✓
    | Tools | Configure is the dialog you need, or use the wrench icon on the toolbar.  Near the bottom is the Projections tab.  

    You can load files that have different "datums" and projections.  This is a major point about Global Mapper.  They will be DISPLAYED using the current setting in Configure | Projections.  The display settings will be used for exported files, unless the export format is defined otherwise (like GPX files, defined as using WGS-84 Lat/Long in decimal degrees).  You DO need to pay attention when your workflow requires changes to your display projection, or you will wind up re-doing your work (if not dealing with embarrassment).  

    I suggest that you start thinking about your data as having a datum AND a projection.  Any data file must have both in order to be used in a GIS system.  You don't have real data unless you know the datum and projection.  

    In your case when you are using the Projection dialog, select (or at least remember to check) your datum, THEN select your projection (although projection is at the top of the dialog implying it comes "first").  All you need is to select the UTM projection.  

    MGRS is more of a display setting for UTM data.  Use it if you need it, otherwise you will have some explaining to do for people unfamiliar with using MGRS coordinates.  Your choice of display format and units is also in the Configure dialog, under the General tab and the Measure/Units subtab.  

    Mykle - the Mavic mapper ... but a really new drone pilot.

Answers

  • MykleMykle Global Mapper User Posts: 442Trusted User
    Import the client file using it's datum and projection, like NAD-27 Geographic coordinates.  If the lat and long values are not in the first two columns, there are a couple of settings in the import dialog to deal with that.  The points should appear on the screen as you expect, with appropriate coordinates appearing on the bottom line of the screen as you mouse around. 

    If this file was the first one that you loaded for this session of Global Mapper, then the coordinate system specified on the bottom line should be the same as the loaded data file.  If you had other files loaded, your coordinate system on the bottom line may be something else. 

    Change the projection of the DISPLAY in the settings dialog, like NAD-27 UTM zone 13. 

    Now you can export your points and they will be in UTM (possibly with lat/long values if you choose).  If there are points from other files being displayed, they will be included in your export.  So, before you export, hide those layers that you don't want to be included. 

    With UTM coordinates, note that the "N" can be misleading, where it can be "N" or "S" for your hemisphere (North of the equator, or South), or it can be the "N" zone in the alphabetical sequence from "C" in the far south to "X" in the far north.  I think that I have the "C" to "X" characters correct, otherwise the start and end characters are close, but you get the idea.  "N" is valid for both systems but has very different meanings.  I usually REQUIRE that it be spelled out: "UTM zone 13 North".  The MGRS grid system is a variation of the UTM grid (same grid definition), and it does use the final letter.   For "normal" UTM, all we need is the hemisphere character like "N". 

    Since you are new to Global Mapper, and perhaps to GIS in general, feel free to ask questions where I have leaped over steps that you may need explained. 


  • droneguydroneguy Posts: 5
    Mykle, thanks for the response.

    Yes, I am quite green to both GM and GIS in general. I appreciate the detailed explanation. 

    Would you mind taking me through the workflow for changing the display projection? I can't say I even see a settings dialogue of where to start. I am currently searching through the GM help guide, so I might find it by the time you reply.

    And are you suggesting I change it to the MGRS grid or is there a specific UTM 13 North system I can select? 

    I really appreciate the help and I apologize for my ignorance!
  • droneguydroneguy Posts: 5
    And when I import the file and it asks to define the projection, I assume I select "Orthographic" or do I use UTM? 
  • MykleMykle Global Mapper User Posts: 442Trusted User
    When you import a file, you use the datum and projection appropriate for that data file.  Again, your DISPLAY is set to whatever you need to look at (and for exports).  Global Mapper will do what it needs to display your data, regardless of the nature of the loaded file(s).  After loading, you can check the gory details by right-clicking the layer/file and selecting Metadata.  Become familiar with the Options selection, as it is very useful.  
  • droneguydroneguy Posts: 5
    Thank you so much for the help, Mykle! I was successful!
Sign In or Register to comment.