Use markers to allign orthomosaics

[Stan]

Hello everybody,

In Agisoft Metashape I have two datasets with photo's from a field in Spain. However, the UAV images are gathered a year apart from each other and are not perfectly overlapping. What I did to try to solve it is to make two chuncks; 1 with 2019 images and 1 with 2020 images. I alligned both chuncks individually and made a DEM and orthomosaic. Since no GCP's are present, I put markers on recognizable locations which are the same for the two chuncks ( A fence, large stone etc.). But when I want to allign the two chuncks (marker based), the only thing that moves are the markers to the markers of the other chunck but the orthomosaic stays on the old location and is not shifted with the markers.

Anybody has an idea what I miss or am doing wrong?
Thanks in advance for your answers!

Stan

[Alexey Pasumansky]

Hello Stan,

Orthomosaic and DEM are isolated processing results, so if you are applying some changes to the chunk, like modifying the referencing information, ortho and DEM will remain unchanged, while dense cloud, mesh and tiled model will move accordingly.

So you need to rebuild the orthomosaic, if the referencing of the corresponding chunk has been modified.

[Stan]

Hi Alexey,

Thank you for your answer! I only struggle to get the two chuncks to allign properly even when I use the markers on the two dense clouds. So the markers of the two chuncks are on the same location only the chuncks differ in XYZ location. I don't know how I can get the two chuncks to align perfectly on each other markers so that I can see the difference in height due to corrosion. The markers are added in the images and seen there. However, when I do 'align chuncks' and then 'marker based' the chuncks still won't perfectly overlap. One thing I can think of is that the fly height of the UAV was different for the two fly dates.

I think I'm close but just not close enough to solve this.
See image in attachement for the chuncks and markers which are not overlapping on the same location as they should be doing (I merged them now so the difference is visible after aligning them).

Thanks in advance!
Stan

[Alexey Pasumansky]

Hello Stan,

Can you please send the project in PSZ format with the alignment results only (tie points clouds, aligned cameras and placed markers) for the original chunks that you are trying to align to support@agisoft.com?