Methods and systems for calibrating fiducial markers relative to an object

In an example, a method for calibrating fiducials relative to a workpiece is disclosed and involves receiving, from one or more cameras, images of the fiducials, each image acquired from a different camera pose, where the fiducials comprise (i) one or more first fiducials fixed at one or more unknown locations on the workpiece and (ii) calibration fiducials disposed at known locations on the workpiece; estimating poses of the fiducials, where estimating the poses of the fiducials comprises, in each image, estimating, for each fiducial visible in the image, a pose of the fiducial relative to the camera(s); formulating a pose graph comprising nodes for the images and for the fiducials, the poses estimated for the fiducials, the calibration fiducials as landmarks with known poses, and constraints between the calibration fiducials and the images; and solving the pose graph to determine poses of the first fiducial(s) that satisfy the constraints.