Automatic Elevation Calibration (to vertical datum)
Understanding Elevation Data
Elevation maps within DroneDeploy are created using standard geo-referenced information embedded in your drone imagery. The elevation data displayed is the absolute elevation in WGS 84.
However, the elevation data from the drone can have some errors due to the error in the drone's GPS and variations in barometric pressure, which DJI also uses to assess altitude. To correct this error or to view your elevation data in a different ellipsoid, you can use Elevation Calibration to enter the known elevation at a point to correct the elevation within your map. Continue reading this doc to learn how.
Calibrate Elevation Data within DroneDeploy
In this section, we will explore:
-
- Calibrating a Non-RTK Map (Manual Calibration)
- Ellipsoid Height
- GCP Maps
- Calibrating an RTK Map (Vertical Datum & Ellipsoid Height)
- Calibrating a Non-RTK Map (Manual Calibration)
1. Calibrating a Non-RTK Map (manual calibration)
There are two ways to calibrate a map:
#1: click on the Map Details button on the left side panel
- Then, select
Calibrate Elevationin the Elevation section.
#2: Click on the Elevation Layer and select Calibrate Elevation:
Either way, you calibrate you will need to select:
- Select
Manual Calibrationfrom the Calibration Method drop-down list & place your known point of calibration on the map.
- Once the known point has been placed on the map input the Calibration elevation and select Calibrate
- 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.
Ground Control Point Maps:
DroneDeploy will NOT apply automatic elevation calibration to any GCP map. We will respect the GCP datum.
If needed, you can also calibrate the elevation values after the GCP processing. This may be necessary if you have processed your map in a coordinate system that uses a different base ellipsoid (common in the UK and Australia). Please review our Processing GCPs with DroneDeploy guide to learn how to add GCP to your DroneDeploy maps.
Ellipsoid Height:
Ellipsoid height will be the default for all DroneDeploy maps, that do not include RTK data.
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.