S-JTSK South West EPSG:5513 upside down transformation

drone10 · May 25, 2023, 11:42am

Hello,
I have been solving the problem for some time and so far without success.
I found several topics here that deal with something similar, but none of the advice I found helped me.
At the same time, I am relatively new to Pix4D. So maybe the solution is trivial.
So far I have transformed the measurements from the drone to our local coordinate system S-JTSK East North EPSG 5514 and there has been no problem.
However, practical circumstances force me to work in S-JTSK South West EPSG 5513 → This is where the problem arises… The entire measurement is suddenly upside down (the cameras are oriented from bottom to top, the lowest point is the highest, etc.) - see photo.

I’ve already tried a lot, but nothing helps - I’d appreciate any helpful advice.

Thanks and have a nice day.

Daniele_Lecci · May 25, 2023, 12:31pm

Hi @drone10,

Welcome to the Pix4D Community

Is it possible for you to share the quality report with us?

Are you using Ground Control Points?
Are you getting the same wrong results if you select " S-JTSK East North EPSG 5514" as the output coordinate for this specific project?

Cheers

drone10 · May 25, 2023, 12:47pm

Hi,
no problem with S-JTSK East North EPSG 5514.
I am not using GCP.
Here is quality report:
zk1_report.pdf (2.1 MB)

Daniele_Lecci · May 25, 2023, 1:03pm

Thank you @drone10,

Have you tried removing the pictures that were taken from different angles?

Is the preview in the quality report correct or is it flipped?

Are you getting the same problem with all projects using S-JTSK South West EPSG 5513 or only with this project?

If you use a subset of images (only 10, for example), are you still having the same problem?

Cheers

drone10 · May 25, 2023, 1:10pm

The preview seems fine.
This project may be a bad example - however the problem is with all other projects I try to transform to EPSG:5513 (even without images from other angles)

It happens with any number of images.

Daniele_Lecci · May 25, 2023, 1:20pm

Thank you for the additional information.

Could you please do the following?

create a small project with 10 images
select the output coordinate system you desire
process the project in order to make sure you are getting the error
send me the 10 images and the .p4d file. You can upload the files here.

Cheers

drone10 · May 25, 2023, 1:31pm

Done.

Thanks for help in advance.

Daniele_Lecci · May 30, 2023, 6:40am

Thank you, @drone10,

I will provide a reply later this week.

Thank you for understanding.

Daniele_Lecci · May 31, 2023, 11:26am

Hi @drone10,

This is a message to inform you that we are still analyzing your request.

It seems that with older versions of PIX4Dmapper the issue is not appearing.

As a workaround, I could suggest you use PIX4Dmapper version 4.4.12.

You can download it from this page:

Let me know if you can get satisfactory results with this version.

Kind regards,
Daniele

drone10 · June 1, 2023, 7:32am

I tried version 4.4.12 and the problem went away. However, I probably know the reason. EPSG 5513 should be a positive coordinate system and in this version it is negative. In the latest version it is correct - there is a positive.

Daniele_Lecci · June 2, 2023, 10:04am

Thank you for trying, @drone10.

Our team is still investigating.
Thank you for your patience.

Daniele_Lecci · June 6, 2023, 9:18am

Hi @drone10,

Please keep in mind that there won’t be any update about CRS handling in PIX4Dmapper on a short term.

If you need to use this CRS, please use PIX4Dmapper 4.4.12. Otherwise, you can try to import a .prj file using the procedure described here:

Let me know how it goes.

Daniele_Lecci · August 14, 2023, 1:54pm

Hi @drone10,

Please download the WKT/PRJ file from here:

https://jjimenezshaw.github.io/crs-explorer/

Please change the axis order in the .prj file and use it to define the corrected coordinate reference system in PIX4Dmapper and let me know how it goes.

Cheers,
Daniele

drone10 · August 16, 2023, 11:46am

Hi Daniele,
maybe I’m too much of an amateur, but I can’t download any file from the link above - only text is displayed and I can’t save the file in .prj format in notepad.

Daniele_Lecci · August 16, 2023, 1:20pm

Hi @drone10,

You can right-click and select Save link as...

You can find the modified .prj file here:

5513.prj (778 Bytes)

drone10 · August 16, 2023, 1:43pm

oh thanks - I thought it would only download the link…
However, the import failed:

Daniele_Lecci · August 16, 2023, 3:13pm

Hi @drone10

Sorry, there was a problem with the shared .prj file.
I replaced the file, please download it again from my previous post.

Please let me know how it goes.

drone10 · August 18, 2023, 4:07pm

Tested in the field… the measurement is no longer upside down, however the whole measurement is shifted by about 3 meters (see picture). I measured the points with a GPS stick.

We need this measurement for projecting blasting work at quarries. Subsequently, we transfer the planned holes to the smart drilling rig, which also has a 5513 coordinate system and it completely matches the points measured with the GPS stick.
It is therefore important that the entire measurement with the drone (or coordinate system) matches the one in the drilling rig.
I confess that I have no idea what the problem could be - why is the whole thing shifted by three meters.

drone10 · August 18, 2023, 4:42pm

I don’t know what it is, but I can’t download a .prj file from the page mentioned above (it always only downloads a .txt and, moreover, with a completely different content than in the .prj file)
Can you please do the same for EPSG 5228 and send me the .prj file here? - I think that could be the solution.
Thank you in advance.

Daniele_Lecci · August 21, 2023, 9:23am

Hi @drone10,

If you download the .txt file, you just need to change the extension from .txt to .prj.

The 3-meter displacement can simply be caused by the GNSS accuracy (are you using a RTK drone?).

You can find additional information here:

You could use Ground Control Points to correctly georeference your project.