Ground control points (GCPs) - PIX4Dmapper

The steps detailed below can be applied to a project where the image geolocation and the ground control points (GCPs) are in a known coordinate system that can be selected from PIX4Dmapper's coordinate system database. The two systems do not need to be the same because PIX4Dmapper is able to do the conversion between two known coordinate systems.

This is the most common project configuration and it allows to mark the GCPs on the images with little manual intervention. However, this method is not suited for "overnight" processing during which the different processing steps start automatically in a row and do not require any supervision by the user.

Instructions

1. Obtain GCP measurements in the field or through other sources.
2. Add/import the GCPs with the GCP / MTP Manager without marking them.
3. On the menu bar, click View > Processing. The Processing bar appears at the bottom of the Main Window.
4. Select 1. Initial Processing and deselect 2. Point Cloud and Mesh and 3. DSM, Orthomosaic and Index.
5. Click Start.
   
6. Once 1. Initial Processing is completed, start the GCP marking procedure in the rayCloud as follows. On the left sidebar, in the section Layers, click Tie Points, then click GCPs / MTPs. The list of GCPs is displayed. Select a GCP in the layer GCPs / MTPs: the right sidebar displays its properties and the list of images in which it is visible. Mark the exact position of the GCP on at least 2 images using the left mouse click. When the green cross is at the correct position in most images, click Apply.
7. Click Process > Reoptimize.
8. (optional) Regenerate the quality report by clicking Process > Generate Quality Report.