Ground Control Points (GCPs) are visual markers on the ground with known coordinates that increase the orthomosaic accuracy and help maintain alignment of multiple surveys. Ground Control Points (GCPs) in other words, are reference points provided by you to improve the positional accuracy of the orthomosaic.
There are two ways to add GCPs,
- By adding them Manually
- By importing a separate file from your machine
(Figure 1 and Figure 2).
Figure 1: Eye icon on the survey thumbnail
Figure 3: Selecting Ground Control Points (GCP) option
Note: You can either add GCPs by uploading a file from your drive or
you can mark them manually.
You must provide at least three GCP points and for each GCP point, you need to
tag minimum three images. The addition of more than three images will lead to
improvement in survey accuracy.
Adding GCP Manually
To manually mark GCPs follow these steps
Figure 4: Selecting Manual Entry
Figure 5: Pointer placed on Google Map
Repeat the procedure to tag next two candidate images (Figure 6).
Note: Candidate Images are the images containing your selected GCP's geo-referenced(GPS) parameters (Latitude, longitude, altitude).
Figure 6: First GCP tagging on a candidate image
Figure 7: Tagged images for the first GCP
Figure 8: Marked GCP
Adding GCP Using a Separate File
To upload GCPs through a separate file follow these steps.