If you fly with a common consumer drone such as a DJI Phantom 4 Pro, the on-board GPS receiver creates geotags with accuracy between five and 10 meters, which is perfectly suitable for high-accuracy mapping provided that adequate ground control is also used to tie down your data.
However, photos taken from certain drones expose geotags that are accurate down to 2cm (0.75in) through employment of an on-board Real Time Kinematic (RTK) or Post-Processed Kinematic (PPK) GPS module.
Specialized off-the-shelf drones such as the SenseFly eBee range, certain DJI setups and some custom-built drones sport this hardware.
Propeller assumes the default accuracy level to be that of a standard, uncorrected drone setup, but high-accuracy geotagged photos can also be processed automatically.
Before you start
It is required that your images are tagged with Latitude and Longitude in decimal degrees. There are requirements for the height field too:
- If you are working on a site with a local coordinate reference system, your tags must have height in meters above the ellipsoid.
- Otherwise, your height system must be either in height above the ellipsoid or the same vertical datum as your ground control, should you choose to add it. More details below.
Submitting a high-accuracy geotag dataset
After selecting your photos, you need only tell us that your submitted photos have high-accuracy geotags in the Create new dataset flow, by checking the box as below.
A word of caution—it is important to ensure that this option is not selected if you are not certain your tags have been corrected.
If you add ground control and/or checkpoints, you must also tell us how the height system of your geotags relates to that of your ground control. To do this, first choose the vertical system of your ground control as below:
Note that if your site has a local coordinate reference system, this defaults to the local system, and we require that your geotags are in ellipsoid height (metres).
If you are working on a published coordinate system, you must now choose a geotag height datum as below. This is subject to the following rules determined by your choice of ground control vertical system:
- If your chosen system is based on a geoid, you can choose either that geoid or ellipsoid height in the same unit.
- If your chosen system is ellipsoid height, you may only choose ellipsoid height.
If you are unsure or would like to know more about achieving accurate data with your drone, check our support knowledge base or reach out to our data specialist support team.