Method for calibrating a camera and methods for determining the location of a subject and methods for tracking a subject

Abstract

A method for calibrating a camera which is in a position and orientation within a predefined coordinate system. The method includes the steps of, (a) moving an object along a trajectory within the predefined coordinate system and within a field of view of the camera; (b) determining the physical location of the object, over time, within the predefined coordinate system; (c) capturing one or more images of the object using the camera as the object is moving along the trajectory; (d) recording the time instant at which each of the respective one or more images are captured; (e) processing each of the one or more images to determine the location of the object in the each of the one or more images, to provide an respective image location for each of respective image; (f) for each of the one or more images, determining a respective expected image location of the object in that image, wherein the expected image location is determined using an initial predefined estimate of camera parameters and the physical location of the object 104 in the predefined coordinate system at the time instant corresponding to the time instant said respective image was captured; (g) optimizing estimates of camera parameters of the camera and/or optimizing an estimate of the position of the camera and/or optimizing an estimate of the orientation of the camera, by minimizing reprojection errors for each of said one or more images, wherein the reprojection error of a respective image is the difference between the expected image location of the object for that image and the image location of the object in said image. There is further provided methods for determining and methods for estimating, a physical location of a subject located within a predefined coordinate system, and methods for tracking the position of a subject, each of which use at least one camera which have been calibrated using the aforementioned method for calibrating a camera.

Dependencies are inferred from the claim text.