Fix projected reconstruction export georeferencing

[lupionpe]

Summary

This ports the consistent projected georeferencing transform into WebODM/OpenSfM.

The core idea and original implementation come from Yann's commit:
YanNoun@446a4b0

This keeps the existing affine export path as the default and adds a projected reconstruction export mode for callers that need the more exact local/topocentric-to-projected transform.

Attribution

Credit for the core georeferencing fix belongs to Yann. I validated and ported the approach into this branch. I have basic coding experience; most of the porting and integration work was done with AI assistance from Codex.

Validation context

I tested the same approach downstream in an ODM/NodeODM pipeline on two real RTK Mavic 3E survey areas. Each test was roughly 1,600,000 m² with about 2,000 images, using gcp.txt and geo.txt. In both areas, the observed final precision improved as expected from Yann's commit.

References

• OpenDroneMap/OpenSfM equivalent PR: Fix projected reconstruction export to use a consistent local->proj transform OpenDroneMap/OpenSfM#48
• OpenDroneMap/ODM integration PR: Keep dense reconstruction topocentric while applying exact final georeferencing OpenDroneMap/ODM#2008
• ODM discussion / prior PR: Try to fix georeferencing accuracy  OpenDroneMap/ODM#1851
• Community discussion: https://community.opendronemap.org/t/what-is-your-biggest-pain-with-odm-opensfm/25791/22
• Community discussion: https://community.opendronemap.org/t/gcp-show-very-good-results-but-is-not-what-i-see-in-reality/25541
• C4 contribution model: https://github.com/OpenDroneMap/documents/blob/master/C4.md

Local checks

• python3 -m py_compile opensfm/actions/export_geocoords.py opensfm/geo.py opensfm/io.py opensfm/commands/export_geocoords.py
• git diff --check

Not run locally:

• pytest, because this shell does not have pytest installed and direct OpenSfM imports require compiled extensions such as pybundle.