Orthomosaik - cylindrical projection (georeferenced)

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Hello everyone,
I would be very happy if someone could help me. I've been trying to unwrap the reveal of a bridge for days. Unfortunately without success.
My model needs to stay georeferenced, so I'm not allowed to rotate the model (need scale). I have attached a few screenshots. could someone tell me the best way to do this or where can I put my markers so that I can do it correctly. Thanks in advance.

Best Regards
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