GlobalMapperMobile elevation data for point collection

pwave1pwave1 Global Mapper UserPosts: 19
I am using GlobalMapperMoblie v.  to collect point data using an EOS Arrow Gold RTK receiver. It has cm resolution. I collect point data using the timed GPS collection feature. I am collecting along a slope that has approx. 10 m relief. When I export the file to Global Mapper (v20.1) and query the point it represented as a whole number, in fact they are all 52 m with no integer values.  Clearly this is not representative of the 10 m slope. Any help would be greatly appreciated.

Best Answer

  • PShoreyPShorey Global Mapper Developer Posts: 191
    Answer ✓
    Thank you so much for sending in your data. It was very helpful. I was able to find a bug in the app which comes into play when using GPS Auto mode to create point features. The result is all points collected during a GPS Auto run will get the first point's elevation. Until an update is available on Apple App Store & Google Play, probably within the next few days, a workaround would be to use GPS Tap mode.


  • pwave1pwave1 Global Mapper User Posts: 19
  • PShoreyPShorey Global Mapper Developer Posts: 191Moderator, Trusted User

    I’m not sure I completely understand the issue. Were you seeing reasonable elevation values on the GM Mobile map view as you moved along the slope, but the values saved to file are vastly different? I'm just wondering if the elevations the system is sending the app are not as expected. Difference in vertical datum? The app does not manipulate elevation data; it should be recording the exact values it receives. It may be a bug, but let's try to verify the elevations the app is receiving first. The values displayed on the map view are the raw values, updated as they are received by the app. If you are still experiencing difficulty, please contact BMG support If possible, it is often very helpful if you can supply us with the data file in question.


  • pwave1pwave1 Global Mapper User Posts: 19
    Thanks Peter. I just ran a short survey with GMM 2.0 collecting from the EOS Arrow Gold. The RTK receiver is collecting sub cm elevation data (I can see that on the EOS software), so, I would assume GM 2.0 should be collecting the same (it is my understanding that the RTK receiver signal overrides the iPad's internal GPS). When we download the GMMP data to GM desktop the elevations are no better than 10 cm. So, I'll send the .gmmp file to BMG support.

  • pwave1pwave1 Global Mapper User Posts: 19
    Thank you for the confirmation. We ran another short survey using GPS Tap mode and found that the recorded elevations do reflect real topographic change. However, they are rounded to the nearest 10 cm. Is there a possibility that the update might include another decimal place?
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