Distance Measurements-Beginning & End Points

When you create a line across terrain, the starting and endpoints of the line are identified as a height value in ft. What is this value relative to? For example, if the starting point is 20 ft, and the endpoint is 7 ft, are these values relative to the takeoff point of the drone, or is it somehow related to sea level? Or none of the above!!!

Many thanks,


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Those values are showing the elevation on the map. The elevations shown on your map depend upon how the pictures were taken and adjustments you made in DD. If you used GCP’s when you flew the mission, then the elevations will be relative to the coordinates for the GCP’s that you uploaded when processing the map. If you did not use GCP’s and you do not have an RTK equipped drone, then the elevations will be relative to the barometer readings of your drone; these have good relative accuracy but terrible absolute accuracy (can vary by 100 feet). You can use the elevation calibration function in DD to match a known elevation at one location on your map; the elevation for other location will be relative to this point. If you have a RTK equipped drone, then the elevations will be determined by the choices you made in processing the data. See other posts for more details.


They are either ellipsoidal heights converted to feet or if used the elevations as derived by your GCP’s.