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Pix4Dmapper Fundamentals online course - GCP coordinate system - Warning w0024

Good afternoon,

I have a small problem about GCP coordinate system. After watching several tutorials still I am not able to fix the problem.

The GCPs points downloaded from “Pix4D fundamentals” are in the wrong position respect the survey area as you can see from the screenshots attached. Surely is a problem with coordinate system. 

Somebody could help me please?

Thank you

 



Hi Michele,

Thank you for sharing screenshots of your project’s map view, output coordinate system, and GCP/MTP manager.

The two most common reasons I have seen that a ground control point’s initial position is in the wrong location is that either the project’s GCP coordinate system is incorrect or the ground control point’s X and Y coordinates are inverted.

Thankfully, you’ll be able to salvage your Pix4Dmapper Fundamentals online course project relatively easily. All you need to do is change your project’s GCP coordinate system and output coordinate system to CH1903+ / LV95. To change your project’s GCP coordinate system and output coordinate system, please follow these steps:

  1. Open the GCP/MTP Manager via the Project dropdown menu
  2. Select all of the GCPs in the list and click Remove Points  to temporarily remove all of the project’s GCPs’ initial position from the project
  3. Select Edit… in the GCP Coordinate System section
  4. Select the  CH1903+ / LV95 coordinate system in the Known Coordinate System [m] text box
  5. Click  OK
  6. Click Import GCPs… to reimport the project’s original GCPs’ initial position
  7. Click  OK after browsing to the file that contains the project’s GCPs’ initial position
  8. (Optional) Repeat steps 1-8 if you receive Warning w0024 again
  9. Click  OK
  10. Confirm that the project’s GCPs’ initial position fall within the extent of the project’s images’ initial position
  11. Open the Select Output Coordinate System  menu via the  Project dropdown menu
  12. Confirm that the project’s output coordinate system says CH1903+ / LV95 in the Known Coordinate System [m] text box
  13. (Optional) Select the  CH1903+ / LV95 coordinate system in the Known Coordinate System [m] text box if it says WGS 84 / UTM zone 32N.
  14. Click  OK
  15. Click Reoptimize  via the  Project  dropdown menu or process Step 1 to play it safe

Another option you can consider is abandoning your latest project and creating a new project. The only difference between your original workflow and new workflow is that you will select the  CH1903+ / LV95  coordinate system in the Known Coordinate System [m] text box in the Select Output Coordinate System menu of the project creation wizard.

I anticipate that your project’s GCP coordinate system and output coordinate system were set to WGS 84 / UTM zone 32N because you selected the Auto Detected option when selecting your project’s GCP coordinate system and output coordinate system in the project creation wizard. If you ever have GCP coordinate measurements, you must select the corresponding coordinate system in the Select Output Coordinate System menu of the project creation wizard to ensure that Pix4Dmapper correctly interprets and projects your project’s GCPs’ initial position.

The Auto Detected option in the Select Output Coordinate System menu of the project creation wizard is, in my opinion, Pix4Dmapper’s attempt to guess what coordinate system you plan to work in based on a limited amount of information and should therefore never be blindly relied on when you plan to incorporate GCPs into a project. If you do not plan to incorporate GCPs in your project and you do not need to define your Pix4Dmapper project’s outputs in a specific coordinate system, you can consider selecting the Auto Detected option in the Select Output Coordinate System menu of the project creation wizard.

Please do not hesitate to let us know if you have any questions incorporating GCPs into the Pix4Dmapper Fundamentals online course project and thank you for your patience.

1 Like

Thank you so much. Your explanation is very clear and now the system works (the first option was fine).

 

Regards