Browse Prior Art Database

Estimation of Camera Motion from Sequences of Video Images

IP.com Disclosure Number: IPCOM000114402D
Original Publication Date: 1994-Dec-01
Included in the Prior Art Database: 2005-Mar-28
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Iwai, S: AUTHOR

Abstract

Disclosed is a method to detect translation parameters, rotational parameters and zooming parameters of a camera from eight pairs of corresponding points between two images. Importance of the invention is as follows: 1. Camera parameters are detected for ordinary cameras and specially equipped cameras are not necessary. 2. Images taken by a camera and images generated by computers can be combined by using detected camera parameters.

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Estimation of Camera Motion from Sequences of Video Images

      Disclosed is a method to detect translation parameters,
rotational parameters and zooming parameters of a camera from eight
pairs of corresponding points between two images.  Importance of the
invention is as follows:
  1.  Camera parameters are detected for ordinary cameras and
specially
       equipped cameras are not necessary.
  2.  Images taken by a camera and images generated by computers can
be
       combined by using detected camera parameters.

      We assume the XYZ coordinate system fixed to the camera.
Movement of the camera is described by a rotational matrix R (3 by 3)
and a translation vector T (3 dimensional vector).  A point  P is
assumed to be (x, y) in the image before camera movement and (x', y')
after camera movement. (1) and (2)  have shown the following:
  (x, y, F) E (x', y', F)t = 0
     where E = T * R E is an essential matrix (3 by 3), ' * '
  represents vector products, and ( )t represents a transposed vector
   of ( ).  The following equation is obtained:
   (x', y', zF) E' (x, y, F)t = 0
  where  E' = T' * R', T' = - R' T z is a zooming factor, R' is
   a transposed matrix of R.  When E' is represented by (e1, e2,
e3)t,
   e1, e2, and e3 are row vectors.
   (x', y', F) (e1, e2, ze3)t (x, y, F) = 0 From this equation z can
  be represented by the following:
  z = sqrt( |e2 * e3'| |(e2, e3')| / (|e1 * e2| |(e1, e2)|) )
  where e3' = z e3, | | represents norm and ( , ) inner products.
   z can be calculated and then R and T can be calculated by solving
   simultaneous equations.

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