Understanding Elevation Data
DroneDeploy uses geo-referenced data embedded in drone imagery to create elevation maps. The elevation data displayed is the absolute elevation in WGS 84, a standard reference system. However, errors can occur due to inaccuracies in the drone's GPS and variations in barometric pressure, which DJI uses for altitude assessment.
You can use Elevation Calibration in DroneDeploy to address this by entering a known elevation point to correct the map's elevation. When using the absolute altitude from the drone's GPS, significant variation in elevation values is possible. DJI blends the GPS elevation with the barometric pressure to get an estimate of the altitude, which causes this.
For the highest accuracy, process maps with Ground Control Points (GCPs). You can learn more in the Elevation Toolbox guide.
This section explores the following:
Calibrating a Non-RTK or PPK Map (Manual Calibration) Ellipsoid Height
GCP Maps
Calibrating an RTK or PPK Map
Ellipsoid Height
Vertical Datum
Calibrate Elevation Access
Calibrating a Non-RTK/PPK Map (Manual Calibration)
There are two ways to calibrate a map:
#1: Through the Map button
Click the Map button on the left side panel.
Select Calibrate Elevation in the Elevation section.
Select Manual Calibration.
Place your known calibration point on the map and type in the height.
Click Calibrate. You can now view a manually calibrated map.
#2: Through the Elevation Layer
Click the Elevation Layer and select Calibrate Elevation.
Then, select Calibrate Elevation in the Elevation section.
Select Manual Calibration.
Place your known calibration point on the map and type in the height.
Click Calibrate. You can now see the elevation
shift.
Once you calibrate the map, you can view the calibration notice in Map Details. The difference between the default elevation and the entered calibration elevation of that specific point adjusts all elevation data associated with the map. The results are reflected in the elevation histograms, elevation visualizations, measurements, and exports.
Ground Control Point (GCP) Maps
DroneDeploy does not apply automatic elevation calibration to any GCP map. We respect the GCP datum. If needed, you can also calibrate the elevation values after GCP processing. This may be necessary if you processed your map in a coordinate system that uses a different base ellipsoid (common in the UK and Australia).
Ellipsoid height is the default for all DroneDeploy maps that do not include RTK data.
Calibrating an RTK or PPK Map (Vertical Datum)
Elevation values from an RTK (Real-Time Kinematic) drone are typically referenced from the WGS84 ellipsoid, which is known as “ellipsoid height”. For RTK or PPK (Post-Processing Kinematic) maps, DroneDeploy automatically performs an elevation calibration to the most likely vertical datum based on the map's location in the world (e.g., NAVD88). As a result, elevation values for RTK and PPK maps in DroneDeploy are reported in “orthometric heights”.
You can easily change the vertical datum referenced or the calibration method if needed.
Vertical Datum
For RTK and PPK maps, DroneDeploy selects the vertical datum that best correlates to your design drawings in orthometric heights. DroneDeploy automatically performs a map calibration to the most likely vertical datum based on the map area (e.g., NAVD88).
Easily change the vertical datum or calibration method if needed. When you upload an RTK or PPK map, you can view the Vertical Datum Calibration. You can also change the EPSG code in the drop-down.
Remove the Calibration
To remove the calibration and return to the default elevation values relative to the drone's takeoff point, click the trashcan icon. A confirmation message will show up confirming that you removed your elevation calibration.
Calibrate Elevation Access
The elevation calibration is available to all Lite, Individual, and Enterprise customers. Learn more about our subscription plans or start your free trial today.
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