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Scale-invariant optical flow in tracking using a pan-tilt-zoom camera

Published online by Cambridge University Press:  09 December 2014

Salam Dhou
Affiliation:
Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, VA 23284-3068, USA
Yuichi Motai*
Affiliation:
Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, VA 23284-3068, USA
*
*Corresponding author E-mail: ymotai@vcu.edu

Summary

An efficient method for tracking a target using a single Pan-Tilt-Zoom (PTZ) camera is proposed. The proposed Scale-Invariant Optical Flow (SIOF) method estimates the motion of the target and rotates the camera accordingly to keep the target at the center of the image. Also, SIOF estimates the scale of the target and changes the focal length relatively to adjust the Field of View (FoV) and keep the target appear in the same size in all captured frames. SIOF is a feature-based tracking method. Feature points used are extracted and tracked using Optical Flow (OF) and Scale-Invariant Feature Transform (SIFT). They are combined in groups and used to achieve robust tracking. The feature points in these groups are used within a twist model to recover the 3D free motion of the target. The merits of this proposed method are (i) building an efficient scale-invariant tracking method that tracks the target and keep it in the FoV of the camera with the same size, and (ii) using tracking with prediction and correction to speed up the PTZ control and achieve smooth camera control. Experimental results were performed on online video streams and validated the efficiency of the proposed method SIOF, comparing with OF, SIFT, and other tracking methods. The proposed SIOF has around 36% less average tracking error and around 70% less tracking overshoot than OF.

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Type
Articles
Copyright
Copyright © Cambridge University Press 2014 

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Supplementary material: PDF

Dhou and Motai Supplementary Material

Supplementary Material

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