DEM exported as XYZ grid, points shifted upwards by approx. .4 meters

My typical workflow for going from a DEM created in Agisoft to autocad is to take the DEM, put it into GM, and create a 3 to 5 meter XYZ grid of points.  However, on a recent project, all the points are being created about .4m above the DEM surface.  I can see this in autocad and in GM.  I found this by importing the point grid I had just exported  in GM back into the GM model, hovering over a point, and looking in the bottom of the screen where it shows the point elevation along with the surface elevation.  This issue is consistent across many points I tested.  What in the world is causing this?  I've done this exact workflow many many times with no issues.

Answers

  • bmg_bobbmg_bob Global Mapper Programmer Posts: 2,002
    Hello,

    What version of Global Mapper are you using? I ran a quick test using the data you provided in Global Mapper 20.1, and the point elevations appear to be the same as the underlying DEM elevations. What did you use for the Elevation Coordinate Precision? I chose "Use Default Precision Based on Units".

    Your best bet is probably to contact Blue Marble Support directly via email (geohelp@bluemarblegeo.com). Please include a detailed description of your workflow, including a screen capture of the options you used to export the DEM to XYZ points, and a sample DEM that will reproduce the problem.

    Cheers,
    Bob
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