Browsing by Author "Chen, I-Hsien"

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A vision-based approach to extracting the tilt angle and altitude of a PTZ camera
(2006-01-01)
Chen, I-Hsien
;
Wang, Sheng-Jyh
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this paper, the relationship between the tilt angle and altitude of a PTZ camera and the 3D-to-2D coordinate transformation is built. A vision-based approach is then proposed to accomplish the estimation of tilt angle and altitude based on the observation of some simple objects lying on a horizontal plane, with known intrinsic parameters of the PTZ camera. The patterns could be a circle, a corner with known angle, more than two corners with unknown but equal angles, or more than two line segments with unknown but equal lengths. Furthermore, if we are given a few line segments with known but not necessarily equal length, the estimation of tilt angle and altitude can also be achieved via an optimization procedure. The impacts of parameter fluctuations are analyzed via computer simulations. Experimental results on real images conform to our analysis and demonstrate the efficiency of this approach.
A vision-based approach to extracting the tilt angle and altitude of a PTZ camera - art. no. 606609
(2006)
Chen, I-Hsien
;
Wang, Sheng-Jyh
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this paper, the relationship between the tilt angle and altitude of a PTZ camera and the 3D-to-2D coordinate transformation is built. A vision-based approach is then proposed to accomplish the estimation of tilt angle and altitude based on the observation of some simple objects lying on a horizontal plane, with known intrinsic parameters of the PTZ camera. The patterns could be a circle, a corner with known angle, more than two corners with unknown but equal angles, or more than two line segments with unknown but equal lengths. Furthermore, if we are given a few line segments with known but not necessarily equal length, the estimation of tilt angle and altitude can also be achieved via an optimization procedure. The impacts of parameter fluctuations are analyzed via computer simulations. Experimental results on real images conform to our analysis and demonstrate the efficiency of this approach.
An efficient approach for the calibration of multiple PTZ cameras
(2007-04-01)
Chen, I-Hsien
;
Wang, Sheng-Jyh
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this paper, we propose an efficient approach to infer the relative positioning and orientation among multiple pan-tilt-zoom (PTZ) cameras. In this approach, the tilt angle and altitude of each PTZ camera are estimated first based on the observation of some simple objects lying on a horizontal plane. With the estimated tilt angles and altitudes, the calibration of multiple cameras can be easily accomplished by comparing the back-projected world coordinates of some common vectors in 3-D space. This calibration method does not require particular system setup or specific calibration patterns. The sensitivity analysis with respect to parameter fluctuations and measurement errors is also discussed. Experiment results over real images have demonstrated the efficiency and feasibility of this approach.
Calibration system for image capture apparatus and method thereof
(2007-08-23)
Chen, I-Hsien
;
Wang, Sheng-Jyh
A calibration system and a method to be used in an image capture apparatus are disclosed. The calibration system includes a calibration appliance, a feature extraction unit and a processor. The calibration appliance has a plurality of mark points. The plurality of mark points is on the same plane to form a line segment with a known length. The image capture apparatus captures an image. Then based on the captured image, the feature extraction unit extracts at least three image feature points corresponding to the mark points. The processor calculates the inclination angle of the image capture apparatus, and the height between the image capture apparatus and the plane. Besides a line segment with a known length, the mark points corresponding to the image feature points may form a corner with a known angle, two corners with unknown but equal angles, or two line segments with unknown but equal lengths. Convenience for the calibration system is therefore improved.
DYNAMIC CALIBRATION METHOD FOR SINGLE AND MULTIPLE VEDIO CAPTURE DEVICES
(2009-08-20)
Chen, I-Hsien
;
Wang, Sheng-Jyh
The present invention discloses a dynamic calibration method for a single and multiple video capture devices. The present invention can acquire the variations of the pan angle and tilt angle of a single video capture device according to the displacement of the feature points between successive images. For a plurality of video capture devices, the present invention includes the epipolar-plane constraint between a plurality of video capture devices to achieve the goal of dynamical calibration. The calibration method in the present invention does not require specific calibration patterns or complicated correspondence of feature points, and can be applied to surveillance systems with wide-range coverage.