in the factory by a robot that waves them around a bunch of tags and we know how to model that we have a model for the camera lenses and we calibrate that and also their poses the problem with that is that they also move around when as the vehicle undergoes temperature changes especially so it's a magnesium frame with plastic pieces and those things expand and contract and any small amount of rotation like even a small fraction of a degree significantly changes the actual results you get when something is 20 meters away so that the