Given multiple cameras pointing at a similar volume, how do we find their relative orientations and locations? In my problem the 4-7 cameras are typically in a field, mounted at arbitary angles, and potentially may not all be able to see the same volume.
OpenCV's triangulation
Potential tools include: whycon https://github.com/lrse/whycon - finding markers in video.
AprilTag https://april.eecs.umich.edu/papers/details.php?name=olson2011tags good for localising the 6DOF of a 2d code from a single image [but I think this turns out to be somewhat inaccurate -- e.g. depth is often difficult, and when a long way away there is some ambiguity about orientation (e.g. could be tilted towards or away from the camera). It also doesn't appear to be for camera registration.
Vicon's camera calibration -- feels quite proprietory. And seems to require that you use the particular hardware etc. https://help.vicon.com/space/Nexus212/11248865/Calibrate+Vicon+cameras
Various papers... https://link.springer.com/chapter/10.1007/978-3-642-42057-3_101 -- uses depth camera.
Off topic -- guessing depth from features https://arxiv.org/abs/2402.04883
MATLAB https://www.sciencedirect.com/science/article/pii/S1474034623002203 -- but this looks close
Various image-matching approaches are related ... https://arxiv.org/abs/2003.01587
https://royalsocietypublishing.org/doi/10.1098/rsif.2018.0653
need to look at https://en.wikipedia.org/wiki/ARTag