Analysis of human activity from a video camera is simpli- fied by the knowledge of the camera¡¯s intrinsic and extrinsic parameters. We describe a technique to estimate such parameters from image observations without requiring measurements of scene objects. We first develop a general technique for calibration using vanishing points and vanishing line. We then describe a method for estimating the needed points and line by observing the motion of a human in the scene. Experimental results, including error estimates, are presented.
Directed solution (without matrix manipulation) of camera parameters from 3 orthogonal vanishing points.
Approximate solution with the knowledge of the vertical vanishing point and the horizon line.
Compute vanishing points/lines from static scene structures: interactions marked on the image.
Compute vertical vanishing point and horizon line by a walking human: the lines connecting the heads and and the lines connecting the feet will intersect on the horizon (L); the lines connecting the head and the foot will intersect on the vertical vanishing point (V).
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