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Author Topic: Re: Ortho image shifts post export  (Read 303 times)

Andysmith321

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Re: Ortho image shifts post export
« on: July 28, 2022, 10:58:35 PM »
I am processing a UAV agriculture land data of around 2 Sq.km with 5 GCP's and ortho images in Metashage have good alignments with GCPs, but once I exported to TIF, and viewed it in other software like Global Mapper GCP's shift randomly around 20-25 cms. What could be a possible cause for this and how can I rectify this error.

Alexey Pasumansky

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Re: Re: Ortho image shifts post export
« Reply #1 on: July 29, 2022, 01:19:16 PM »
Hello Andysmith321,

Shifted orthomosaic can be a result of inaccurate georeferencing. Do you use GCP to reference the project or the coordinates of the camera locations? If only camera locations are used, then how accurately they are measured - RTK/PPK or regular onboard GPS accuracy?

Also please check, how big are adjusted values of Cx and Cy in the camera calibration dialog.
Best regards,
Alexey Pasumansky,
Agisoft LLC

flyzk

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Re: Ortho image shifts post export
« Reply #2 on: July 29, 2022, 04:24:42 PM »
from my understanding, he doesn't speak about absolute position accuracy, but about a shift when exporting orthomosaic.
it means, that the orthomosaic visually matches with GCPs on agisoft, but after exporting, and using in GIS software and comparing with GCPs, it seems the orthomosaic is shifted.

Others bug reports in this forum also show this "shifted issue"

I also noticed this issue from 1.8.3 when exporting with a different SCR


Would be nice if agisoft can looking for this issue ,  in order to provide a fix soon, this is a real big problem.
« Last Edit: July 29, 2022, 04:26:47 PM by flyzk »

Alexey Pasumansky

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Re: Re: Ortho image shifts post export
« Reply #3 on: July 29, 2022, 06:02:59 PM »
If there are any check points (markers with the measured reference coordinates, but unchecked in the Reference pane), do they show acceptable errors or if the Error (m) values for them are close to the orthomosaic "shift"?
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Alexey Pasumansky,
Agisoft LLC

Paulo

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Re: Ortho image shifts post export
« Reply #4 on: July 29, 2022, 06:57:26 PM »
On my side I do not see any shift when I export the ortho and superimpose the GCPs in Global mapper....
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Paul Pelletier,
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