There are different ways to add GCPs to a project acquired with Pix4Dcatch.
One option involves using Pix4Dmapper:
- Export the images from Pix4Dcatch (iOS / Android).
- Create a New project in Pix4Dmapper importing the images taken with Pix4Dcatch.
- Import and mark the GCPs: How to import and mark ground control points (GCPs).
- Process locally in Pix4Dmapper and eventually upload the results to Pix4Dcloud, if needed. Alternatively, upload the project files for processing on Pix4Dcloud.
Another option involves processing with Pix4Dcloud. This method can only be used if some requirements are met, among which having black and white squared or diagonal targets and nadir images. Please, consult the full requirements list here.