--pmvs-min-images and --force-focal flags

Hi,
I have been told that in the past (at least), I needed to use --pmvs-min-images 2 so that ODM uses features found in 2 images. This is because I have poor overlap. I am using historical areal photography. Does this flag still exist? I am also looking for --force-focal. Images are taken with a 152.4mm focal.
Thanks for your help.
Nicolas

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We do not expose these options, unfortunately.

You might have to manually edit the OpenSFM config on disk.

Could Focal information be taken from EXIF info (FocalLength parameter) ?

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Normally it would be, but I believe these data do not have much, if anything, by way of metadata given they’re old scans of film.

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But you can calculate some values, I have some historical images but I cannot follow this procedure since I have no the coordinates like there but I have gcp_list.txt file with spatial and images coordinates.
I try to run ODM but it failed after that I realize my tif has no EXIF at all. So I could add some parameters like fixed focal lenght, images dimension and others but I don’t know if this could help.
If they are read by ODM, which are really needed?

Thanks

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If you’re going to be adding geoinformation to files that don’t have it, the geo.txt file is the proper way to do so, not the gcp_list.txt file.
https://docs.opendronemap.org/geo/

What information do you have that you could possibly add to the EXIF and/or the geo.txt file?

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If you have an Idea what the Lense was, you could try to get the same pictures of this Areal with a Mavic 2 zoom (adjustable lense). Than you could get an idea of the correct gps. (For sure with gps offset but I guess better than just trying to guess)

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Indeed,
All I had was the flight altitude(20,000 feet), the focal-Length (152.4mm) and the film size (9x9inch)
Nicolas

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Yes,
Start with the geo.txt file. You can use the gcp_list.txt to georeference the files. Use a Helmert transformation. Then use the scene centre and the angle of the scene (kappa), to make the geo.txt file. If you are successful, then try to refine with the gcp_list.txt file.
Nicolas

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Hi,
That could be complicated with a landscape that no longer exists and a flight altitude of 20,000 feet! I guess that could work in other situations.
Thanks
Nicolas

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Same here, but I have also some GCP taken few years ago with GPS finding some places on the old images

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Thanks Nicolas,

could you explain a little bit better how to create create the geo.txt from the gcp_list.txt? I understood you suggest to apply a trasformation, how?

thank a lot

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