GCP's vs Calibrating Map


#1

What is the difference in accuracy between setting ground control points and using the calibration tool in an already processed map with a known point?


#2

It depends on the accuracy of the drone’s GPS and the conditions for that day. I would try to keep the calibration around the middle of the project so that the error projects out towards the boundaries. I would expect no better accuracy than 3ft (1m) at the edges.
GCP’S localize your site and spread out that error so that you are +/- 2-3in (7cm) between them…


#4

Hi @hts,

Thanks so much for your inquiry. To complement Michael’s response, adding GCPs is a great way to increase the accuracy of your map from within a couple of feet/meters to within inches/centimeters. This accuracy adjustment is performed by using the 3 dimensions information from your GCP targets, X, Y, and Z or Northing, Easting, and Elevation.

The calibration tool, on the other hand, only adjust the elevation (Z value) at a given point. That being said, calibrating the elevation does not take into account the X, and Y data and the accuracy of the map won’t be improved to inches or centimeter level.

Hope this information is helpful. Happy mapping!

Best,
Andrea