1. A dynamic calibration method for video capture devices, comprising: providing a plurality of video capture devices each capable of independent panning and tilting; operatively coupling said plurality of video capture devices to a computer system; capturing at least one initial image by each of said plurality of video capture devices; controlling, through said computer system, panning or tilting of said each video capture device for capturing at least one successive image with different angles, and comparing, by said computer system, said at least one initial and at least one successive images captured by different of said plurality of video capture devices to obtain calibration pan and tilt angles through the steps of: processing, at said computer system, said at least one initial image captured by said each video capture device by extracting at least one initial feature point from said at least one initial image of said each video capture device, and forming an epipolar plane according to projection centers and said at least one extracted initial feature points on said at least one initial images taken by said each video capture device in each pair of video capture devices from said plurality thereof; extracting at least one second feature point from said at least one successive image, wherein said at least one second feature point corresponds to said at least one initial feature point and is located on said epipolar plane of corresponding said each pain of video capture devices, wherein said at least one initial and said at least one second feature points extracted from said at least one initial and successive images captured by a first video capture device from said each pair thereof correspond to at least a first 3-D point, and wherein said at least one initial and said at least one second feature points extracted from said at least one initial and successive images captured by a second video capture device from said each pair thereof correspond to at least a second 3-D point; and acquiring, by said computer system, variations of a pan angle and a tilt angle of said each video capture device according to an epipolar-plane constraint corresponding to said each pair of video capture devices, wherein said at least first 3-D point deviates from said at least second 3-D point.