Matthias Zobel

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Active object tracking, for example, in surveillance tasks, becomes more and more important these days. Besides the tracking algorithms themselves methodologies have to be developed for reasonable active control of the degrees of freedom of all involved cameras. In this paper we present an information theoretic approach that allows the optimal selection of(More)
Abstract. This contribution introduces MOBSY, a fully integrated, autonomous mobile service robot system. It acts as an automatic dialogue-based receptionist for visitors to our institute. MOBSY incorporates many techniques from different research areas into one working stand-alone system. The techniques involved range from computer vision over speech(More)
In this paper, we consider the problem of robust localization of faces and some of their facial features. The task arises e.g. in the medical field of visual analysis of facial paresis. We detect faces and facial features by means of appropriate DCT coefficients that we obtain by neatly using the coding capabilities of a JPEG hardware compressor. Beside an(More)
In active visual 3-D object tracking one goal is to control the pan and tilt axes of the involved cameras to keep the tracked object in the centers of the fields of view. In this paper we present a novel method, based on an information theoretic measure that manages this task. The main advantage of the proposed approach is that there is no more need for an(More)
Plenoptic models, representatives are the lightfield or the lumigraph, have been successfully applied in computer vision and computer graphics in the past five years. The key idea is to model objects and scenes using images and some extra information like camera parameters or coarse geometry. The model differs from CAD–models in the photorealism that can be(More)
We describe a method for selecting optimal actions affecting the sensors in a probabilistic state estimation framework, with an application in selecting optimal zoom levels for a motor-controlled camera in an object tracking task. The action is selected to minimize the expected entropy of the state estimate. The contribution of this paper is the ability to(More)
Geometric object models have been widely used for visual object tracking. In this contribution we present particle filter based object tracking with pose estimation using an appearance based lightfield object model. A light-field is an image-based object representation which can be used to render a photo realistic view of an arbitrarily shaped object from(More)
In this paper we present an information theoretic framework that provides an optimality criterion for the selection of the best sensor data regarding state estimation of dynamic system. One relevant application in practice is tracking a moving object in 3–D using multiple sensors. Our approach extends previous and similar work in the area of active object(More)
In this paper we discuss some practical facets of active camera control during 3-D object tracking. The basis of our investigation is an active binocular camera system looking onto a scene to track a moving object in 3-D. Tracking is done in a data driven manner using an extented version of the region based method that was proposed earlier by Hager and(More)