Reactive Zoom Control while Tracking

This paper presents a method for automatically adjusting the zoom setting of an active camera undergoing pure rotation so that it maintains the ratio of projected areas in the scene and image around the fixation point. We restrict discussion to planar objects, and exploit the properties of the two different interimage transformations which are observed — the infinity homography describing correspondences between points projected into the rotating camera from the static background, and the regular plane-to-plane homography between views of the foreground plane which can both rotate and translate freely. Results are presented from real imagery captured from an active camera in both snapshot and real-time operation.