Browsing by Author "Caseiro, Rui"
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- Active stereo tracking of multiple free-moving targetsPublication . Perdigoto, Luis; Barreto, João P.; Caseiro, Rui; Araujo, Helder; Perdigoto, Luis;This article presents a general approach for the active stereo tracking of multiple moving targets. The problem is formulated on the plane, where cameras are modeled as ”line scan cameras” and targets are described as points with unconstrained motion. We propose to control the active system parameters in such a manner that the images of the targets in the two views are related by an homography. This homography is specified during the design stage and implicitly encodes the tracking behavior. It is shown that this formulation leads to an elegant geometric framework that enables to decide about the feasibility of a particular active tracking task. We apply it to prove that two cameras with rotation and zoom control, can track up to three moving targets, while assuring that the image location of each target is the same for both views. In addition, the framework is also useful for devising tracking strategies and deriving the required control equations. This feature is illustrated through a real experiment on tracking two independent targets using a binocular stereo head.
- Active stereo tracking of N ≤ 3 targets using line scan camerasPublication . Barreto, Joao P.; Perdigoto, Luis; Caseiro, Rui; Araujo, HelderThis paper presents a general approach for the simultaneous tracking of multiple moving targets using a generic active stereo setup. The problem is formulated on the plane, where cameras are modeled as line scan cameras, and targets are described as points with unconstrained motion. We propose to control the active system parameters in such a manner that the images of the targets in the two views are related by a homography. This homography is specified during the design stage and, thus, can be used to implicitly encode the desired tracking behavior. Such formulation leads to an elegant geometric framework that enables a systematic and thorough analysis of the problem at hand. The benefits of the approach are illustrated by applying the framework to two distinct stereo configurations. In the first case, we assume two pan-tilt-zoom cameras, with rotation and zoom control, which are arbitrarily placed in the working environment. It is proved that such a stereo setup can track up to N = 3 free-moving targets, while assuring that the image location of each target is the same for both views. The second example considers a robot head with neck pan motion and independent eye rotation. For this case, it is shown that it is not possible to track more than N=2 targets because of the lack of zoom. The theoretical framework is used to derive the control equations, and the implementation of the tracking behavior is described in detail. The correctness of the results is confirmed through simulations and real tracking experiments.