Ground control points are required to create a high-accuracy photogrammetry model of your site. Checkpoints are an optional way to verify the accuracy of a generated model against data collected on-site.
To learn more about photogrammetry, check out our blog post that details how we turn drone photos into 3D surveys.
Ground Control Points
Ground control points (GCPs) are precise, measured locations on Earth used in building aerial surveys. A global positioning system (GPS) rover determines the northing, easting, and elevation of a point. A high-contrast physical marker is placed on top to serve as a reference point in the images captured by a drone.
During processing, we link markers in images with exact GPS data to more closely align real-world measurements with the digital model. This means GCPs improve the accuracy of the finished model.
Checkpoints are locations in the drone images (they do not need to be visible in the images) where the precise GPS location is known. Checkpoints are not used during processing, so instead of improving the accuracy of your map, checkpoints are used to verify its accuracy.
AeroPoints can function as GCPs or as checkpoints when creating a model of your site. During the imagery upload, after selecting the method of ground control, you can mark each AeroPoint as either a GCP, checkpoint, or you can exclude the point from your survey.
This lets our data team know how to process your GPS information and ensure that your survey comes back with accurate data.
When using multiple AeroPoints on your site, we require at least one to function as a GCP.
AeroPoints save time compared to traditional surveying methods because of how easily they can be deployed, capture data, and upload to the AeroPoints Dashboard in your portal. Along with a drone like the Mavic 3 Enterprise, AeroPoints can help you get survey-grade accuracy for your site model.
Want to Learn More?
We have articles to help you get up to speed:
- What are AeroPoints?
- How to Use Ground Control
- How to Optimize Your Ground Control Point Placement
- Submitting GCPs and Checkpoints with Propeller
- GCP Limit on Propeller
I still can't do it!
We wrote these articles to equip you with everything you need to get the job done on your own, but we understand that sometimes this isn't sufficient.
If you're stuck, the Propeller Hardware Support team may be able to help. You can contact our support team by emailing firstname.lastname@example.org or by clicking the support tab on the top-right pane of your user portal.