Using GCPs and MTPs from PIX4Dcatch in PIX4Dmatic

Ground control points (GCPs) are reference points with known coordinates, typically measured using RTK/PPK GNSS receivers or total stations. In PIX4Dcatch, GCPs can be created manually or automatically with the use of Autotags. To use GCPs in PIX4Dmatic, both the image marks and the corresponding point coordinates must be exported and imported.

Manual tie points (MTPs) are 3D features marked in images that help improve the quality and accuracy of the reconstruction. In PIX4Dcatch, MTPs are generated automatically using Autotags. Unlike GCPs, only the image marks are required since coordinate data is not needed for import into PIX4Dmatic.

Export from PIX4Dcatch

Exporting automatic GCPs using Autotags

GCPs require the image marks and the point collection to be transferred from PIX4Dcatch to PIX4Dmatic.

1. Open the Projects tab and select a project with GCP Autotags.
2. Tap the Export icon.
3. Select Export Points & Marks.
   
   
   
4. Choose the export method (e.g., email, cloud storage).
   
   

A .zip file will be generated containing:

• marks-PIX4Dmatic.csv
  
  
• name_of_point_collection-PIX4Dmatic.csv

Import into PIX4Dmatic

Import GCP Coordinates

1. Open the Tie Points tab from the control panel in PIX4Dmatic.
2. Drag and drop “name_of_point_collection-PIX4Dmatic.csv” into the window or select it manually.
   
   
3. Set the column format to PENZ (point, easting, northing, elevation).
   
   
4. Review the preview table and click Apply.
   
   
   
   
5. GCPs will appear in the Tie Points tab.
6. Set the proper coordinate reference system by clicking the pencil icon.
   
   
   
   

Import GCP Image Marks

1. In the Tie Points tab, click the more options icon.
2. Select Import Marks.
   
   
3. Choose the file "marks-PIX4Dmatic.csv".
4. The table will update with the mark positions.
   
   

 

Import Tie Point Marks

MTPs only need the image marks imported and do not require a point collection file.

1. In the Tie Points tab, click the more options icon.
2. Select  Import Marks.
   
   
   
   
3. Choose the file “catchTagsMarks.csv.”
4. Tie points will be added and automatically classified as MTPs.
   
   

Process the Project in PIX4Dmatic

1. After importing GCPs and/or tie points,go to the Processing setting and select the PIX4Dcatch processing template.
   
   
   
2. Adjust settings as needed.
3. Click Start to begin processing.
   
   You can find more information about Processing here and here.