Hello Thibaut,

I can suggest the following code to perform the conversion of the coordinate information for every camera and marker in the reference pane from the current chunk coordinate system to the user-defined coordinate system:

chunk = PhotoScan.app.document.chunk
out_crs = PhotoScan.CoordinateSystem("EPSG::3946") #user-defined crs
for camera in chunk.cameras:
    if camera.reference.location:
        camera.reference.location = PhotoScan.CoordinateSystem.transform(camera.reference.location, chunk.crs, out_crs)
for marker in chunk.markers:
    if marker.reference.location:
        marker.reference.location = PhotoScan.CoordinateSystem.transform(marker.reference.location, chunk.crs, out_crs)
chunk.crs = out_crs
chunk.updateTransform()