Keywords
camera tracking, pose estimation, football,
soccer |
Abstract
When broadcasting sports events such as football, it is useful to be
able to place virtual annotations on the pitch, to indicate things such
as distances between players and the goal, or whether a player is
offside. This requires the camera position, orientation, and focal
length to be estimated in real time, so that the graphics can be
rendered to match the camera view. Whilst this can be achieved by
using sensors on the camera mount and lens, they can be
impractical or expensive to install, and often the broadcaster only
has access to the video feed itself. This paper presents a method for
computing the position, orientation and focal length of a camera in
real time, using image analysis. The method uses markings on the
pitch, such as arcs and lines, to compute the camera pose. A novel
feature of the method is the use of multiple images to improve the
accuracy of the camera position estimate. A means of automatically
initialising the tracking process is also presented, which makes use
of a modified form of Hough transform. The paper shows how a
carefully-chosen set of algorithms can provide fast, robust and
accurate tracking for this real-world application.
This paper was published in the Journal of Real Time Image
Processing, Vol. 2, No. 2-3, November 2007, pp. 117-132. It is an
extended version of a similar paper presented at CVMP2006,
published as WHP146. |
