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Human Motion Tracking with a Kinematic Parameterization of Extremal Contours

David Knossow 1 Rémi Ronfard 1 Radu Horaud 1
1 MOVI - Modeling, localization, recognition and interpretation in computer vision
GRAVIR - IMAG - Graphisme, Vision et Robotique, Inria Grenoble - Rhône-Alpes, CNRS - Centre National de la Recherche Scientifique : FR71
Abstract : This report addresses the problem of human motion tracking from image sequences. The human body is described by an articulated mechanical chain and human body-parts are described by volumetric primitives with curved surfaces. An extremal contour appears in an image whenever a curved surface turns smoothly away from the viewer. We describe a method that relies on a kinematic parameterization of such extremal contours. The apparent motion of these contours in the image plane is a function of both the rigid motion of the surface and the relative position and orientation of the viewer with respect to the curved surface. First, we describe a parameterization of an extremal-contour point, and its associated image velocity, as a function of the motion parameters of the kinematic chain associated with the human body. Second, we introduce the zero-reference kinematic model and we show how it may be used for human-motion modelling. Third, we show how the chamfer-distance may be used to measure the discrepancy between predicted extremal contours and observed image contours; Moreover we show how the chamfer distance can be used as a differentiable multi-valued function and how the tracker based on this distance can be cast in an optimization framework. Fourth, we describe a practical human-body tracker that may use an arbitrary number of cameras. One great methodological and practical advantage of our method is that it relies neither on model-to-image, nor on image-to-image point matches. In practice we model people with 5 kinematic chains, 19 volumetric primitives, and 54 degrees of freedom; We observe silhouettes in images gathered with several synchronized and calibrated cameras. The tracker has been successfully applied to several complex motions gathered at 30 frames/second.
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https://hal.inria.fr/inria-00104098
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Submitted on : Thursday, November 2, 2006 - 10:37:42 AM
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  • HAL Id : inria-00104098, version 2

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David Knossow, Rémi Ronfard, Radu Horaud. Human Motion Tracking with a Kinematic Parameterization of Extremal Contours. [Research Report] RR-6007, INRIA. 2006, pp.38. ⟨inria-00104098v2⟩

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