Ground control point manager
Ground Control Point Manager¶
The Ground Control Point Manager is used for:¶
- Adding ground control points manually.
- Importing ground control point files. Supported formats: txt, csv, pxg.
- Exporting ground control point files. Supported formats: txt, csv, pxg.
To import GCP's from a file go to the Ground Control Point Manager and press import. Choose a file in your computer and select appropriate field settings and coordinate system. It is imperative to select the correct settings or the GCP's will not be placed correctly. You can see a preview map of where the GCP's are located. If it looks correct - you are good to go. Correctly imported GCP's in the GCP manager should look similar to this:
If you want to add GCP's manually in the GCP Manager window, click Add GCP. The GCP point location window opens. From this point there are two options:
- Inputting GCP coordinates in WGS or UTM formats to the appropriate fields in the upper part of the window.
- Placing points on the world map by simply clicking left mouse button on the world map view.
After using any of the aforementioned methods press OK.
When the Add GCP window opens, pictures made nearby the GCP are identified (in the list and map view). In these identified images find the correct GCP and mark the exact place of the GCP on the photo with the circle by clicking left mouse button. After marking 2 pictures as precisely as possible all other photos where the GCP is visible will be adjusted. Go through these adjusted images and make sure the markers are placed as accurately as possible. Its is recommended to adjust all points manually, but if the point is perfect already just press Approve. Projection error should not exceed a dozen pixels. When finished press OK and GCP1 will appear on the Layers Panel at the Ground Control Points section. Repeat this process for as many GCP’s as required. An example of correctly placed GCP:
There can be 3 states of GCP's that are displayed in the Modified column:
- Estimated - the GCP was estimated automatically to aid placement. Estimated GCP projections will not be used to triangulate the 3D position.
- Modified - GCP has been edited manually but cannot be used for triangulation.
Manual - GCP has been edited manually and can be used for triangulation. Only the GCP's with manual state will be used for GCP 3D triangulation.
Editing Ground Control Points Click Ground Control Point Manager button in the top menu. In the GCP Manager window, select the GCP from the list, and click Edit GCP. The list with the projected GCPs and the used photos for projections is displayed. After inspecting and, if necessary changing the GCP position in all relevant images, click OK to finish editing the GCP.
The Unset option allows unsetting the GCP on several photos with one click. To unset, left-click and drag over the photos where the GCP needs to be removed. When finished, click Unset button. To confirm the changes and close the window, click OK.
- Remove Ground Control Points Right-click the GCP1 (or any GCP from the list) on the Layers Panel, and click Remove GCP. For a detailed workflow how to add GCP's in Pixpro go to Ground control point workflow