You need a lot more than one reference though. At minimum I think you need 8 correspondences to solve for the camera’s pose. Things like airplanes could work if

You need a lot more than one reference though. At minimum I think you need 8 correspondences to solve for the camera’s pose. Things like airplanes could work if you had enough of them, but then the imagery in all your cameras would have to be shutter synced, which is impractical with a bunch of web cams