Wide Area Camera Calibration Using Virtual Calibration Objects

unsynchronized cameras with respect to a single global coordinate
system. The method is simple and does not require the physical
construction of a large calibration object. The user needs only wave an
identifiable point in front of all cameras. The method generates a rough
estimate of camera pose by first performing pair-wise
structure-from-motion on observed points, and then combining the
pair-wise registrations into a single coordinate frame. Using the
initial camera pose, the moving point can be tracked in world space. The
path of the point defines a "virtual calibration object", which can be
used to improve the initial estimates of camera pose. Iterating the
above process yields a more precise estimate of both camera pose and the
point path. Experimental results show that the algorithm performs as
well as calibration from a physical target, in cases where all cameras
share some common working volume. We then demonstrate its effectiveness
in wide area settings by calibrating a system of cameras in a
configuration where traditional methods cannot be applied directly.