An important problem in active 3-D vision is updating the camera calibration matrix as the focus, aperture, zoom or vergence angle of the cameras changes dynamically. Techniques are presented to compute the projection matrix from five-and-a-half points in a scene without matrix inversion, and to correct the projective transformation matrix by tracking reference points. The authors' experiments show that a change of focus can be corrected by an affine transform obtained by tracking three points. For a change in camera vergence, a projective correction, based on tracking four image points, is slightly more precise than an affine correction matrix. It is shown how stereo reconstruction makes it possible to 'hop' a reference frame from one object to another. Any set of four non-coplanar points in the scene may define such a reference frame. It is shown how to keep the reference frame locked onto a set of four points as a stereo head is translated or rotated. These techniques make it possible to reconstruct the shape of an object in in its intrinsic coordinates without having to match new observations to a partially reconstructed description.<>


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    Title :

    Maintaining stereo calibration by tracking image points


    Contributors:
    Crowley, J.L. (author) / Bobet, P. (author) / Schmid, C. (author)


    Publication date :

    1993-01-01


    Size :

    554420 byte





    Type of media :

    Conference paper


    Type of material :

    Electronic Resource


    Language :

    English



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