Calibrate Elevation

Automatic Elevation Calibration (to vertical datum)

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. To address this, you can use Elevation Calibration in DroneDeploy by entering a known elevation point to correct the map's elevation. When using the absolute altitude from the drone's GPS, there is room for significant variation in elevation values. That’s because DJI blends the GPS elevation with the barometric pressure to get an estimate of the altitude. This means that if there is a temperature difference, then the drone will register a different absolute elevation. This is the reason we implemented the elevation calibration tool, as we can’t rely on the absolute altitude from DJI.

For more details, refer to DroneDeploy's Elevation Toolbox guide. For the most accurate results, it's recommended to process your map with Ground Control Points.

Calibrate Elevation Data within DroneDeploy

In this section, we will explore:

1. 1. Calibrating a Non-RTK Map (Manual Calibration)
      • Ellipsoid Height 
      • GCP Maps 
   2. Calibrating an RTK Map
      • Ellipsoid Height
      • Vertical Datum
   3. Calibration Elevation Access

1. Calibrating a Non-RTK Map (manual calibration) 

There are two ways to calibrate a map:

#1: Through Map Details

1. Click on the Map button on the left side panel
2. Then, select Calibrate Elevation in the Elevation section.
3. Select Manual Calibration, place your known point of calibration on the map & type in the height. 
4. Click on Calibrate and you'll be able to view a manually calibrated map 

#2: Through Elevation

1. Click on the Elevation Layer and select Calibrate Elevation:
2. Then, select Calibrate Elevation in the Elevation section.
3. Select Manual Calibration, place your known point of calibration on the map & type in the height. 
4. Click on Calibrate and you'll be able to see the elevation shift

Once calibrated you can view the calibration notice in Map Details:

All elevation data associated with the map will be adjusted using the difference between the default elevation and the entered calibration elevation of that specific point. The results would be reflected in the elevation histograms, elevation visualizations, measurements, and exports. 

2. Calibrating an RTK Map (Vertical Datum) 

Elevation values from an RTK drone are typically referenced from the WGS84 ellipsoid, this is known as “ellipsoid height”. For RTK maps, DroneDeploy automatically performs an elevation calibration to the most likely vertical datum based on the map’s location in the world (Eg NAVD88). The result is elevation values for RTK maps in DroneDeploy are now reported in “orthometric heights”. Easily change the vertical datum referenced or calibration method if needed.

Vertical Datum:

For RTK maps, DroneDeploy will select 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 (Eg NAVD88). Easily change the vertical datum or calibration method if needed.

• When an RTK map has been uploaded 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 on the trashcan icon.

• A confirmation message will show up confirming that your elevation calibration has been removed.

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.