Bounding box skewed!

[DRONE@WORK]

For this project I took geo-ref photos with Aibot X6 uav, the purpose is to create a las file to open in Revit.
When i allign photos, the bounding box is skewed in relation to my project.
My workflow is: add photos, allign photos with reference, convert to Belge1972 coordinates (as GCP's), import markers (measured with rtk). Uncheck cameras, optimize and update. The bouding box stays skewed.
After i converted the photos to belge1971, I see the altitude changes from +/- 50m to +/- 9m
I attached small version of photos and markers. Is there a problem with my photos?
Can someone help me please?

Thank you

[Alexey Pasumansky]

Hello DRONE@WORK,

Can you please post a screenshot, so that we could understand what do you mean?

Is the bounding box just not properly oriented, or it doesn't any longer have normal angles.

[DRONE@WORK]

This is screensht of the project
I manually adjusted the gcp's

[Alexey Pasumansky]

Are you sure that the alignment is correct?

If so, then you can use Reset Region option in the Tools Menu or manually adjust the position and orientation of the box, as by default it is based on the sparse cloud points distribution and not on the geographic axis.

[DRONE@WORK]

But why does my altitude changes when I convert my photos from wgs84 to Belge1972?

[Alexey Pasumansky]

Hello DRONE@WORK,

Altitude values may be different if coordinate systems uses different Datums, since different ellipsoids could be used.

[stihl]

My advice is to convert all your coordinates to the same CRS before aligning anything in photoscan.

Your geo-refed images are probably in WGS, which you first need to convert to your mentioned CRS and then use those to align the images before adding the GCP's to the sparse point cloud and optimizing the model.

Make sure not to convert the height(Z-axis) of the images as that value is most likely the AGL and Not te WGS altitude.

[DRONE@WORK]

Stihl,

Thank you for your feedback

i always convert my images in photoscan to the crs of my gcp.
But when I do that, z always changes a lot (images are amsl)