Device-tagged feature-based localization and mapping of wide areas with a PTZ camera

This paper proposes a new method for estimating and maintaining over time the pose of a single Pan-Tilt-Zoom camera (PTZ). This is achieved firstly by building offline a keypoints database of the scene; then, in the online step, a coarse localization is obtained from camera odometry and finally refined by visual landmarks matching. A maintenance step is also performed at runtime to keep updated the geometry and appearance of the map. At the present state-of-the-art, there are no methods addressing the problem of being operative for a long period of time. Also, differently from our proposal these methods do not take into account for variations in focal length. Experimental evaluation shows that the proposed approach makes it possible to deliver stable camera pose tracking over time with hundreds of thousand landmarks, which can be kept updated at runtime.