Ground control points make terrain vertical

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  • Reuben
    3Dfollower
    • Jul 2017
    • 21

    Ground control points make terrain vertical

    I imported drone images of flat terrain and created a sparse point cloud. I then manually picked 4 ground control points and entered my gps measurements for each point. However, when I click 'scale model with control points' the terrain gets rotated 90 degrees, and now the ground is vertical. My control points are:

    "4" 18.0406852537753 59.3667233564515 34.94957450823554
    "2" 18.19012302092227 59.35790458641403 34.8401551166948
    "1" 18.07460485122671 59.36359861522732 34.83832869271857
    "5" 17.96671772491363 59.37044405717378 34.85027037506988

    There are pink arrows pointing away from the GCPs, am not sure what these are indicating?

    I attached screenshots:
  • Roberto
    3Dflow
    • Jun 2011
    • 559

    #2
    Hi Reuben,

    I think the problem is that latitude and longitude coordinates are inverted. Can you please try to invert x-y when importing? There's also a command to invert coordinates directly from the "scale world with control points" dialog: right click in the points table and select 'invert x-y'
    Last edited by Roberto; 2017-07-02, 05:54 PM.

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    • Roberto
      3Dflow
      • Jun 2011
      • 559

      #3
      I've just noticed also that the reference system is not set correctly. The input system should be set to 'Geographic' as you are using lat-long values.
      The pink arrows connect the input control points positions to the control points coordinates computed after the the transformation. The length of the arrow is the error.

      Please let me know if It works by inverting the coordinates and changing the input system or if I can be of any further help!

      Comment

      • Reuben
        3Dfollower
        • Jul 2017
        • 21

        #4
        Thank you very much Roberto! Of course it was the input coordinate system! Changed that to Geographic and now my errors are <40cm. Cheers!

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