Television – Monitoring – testing – or measuring
Reexamination Certificate
2000-11-14
2003-09-09
Miller, John (Department: 2614)
Television
Monitoring, testing, or measuring
C348S191000, C348S745000, C348S746000, C348S747000, C348S175000, C348S177000, C345S156000, C345S158000, C353S122000
Reexamination Certificate
active
06618076
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to calibration systems and, in particular, to the automatic calibration of a projector-camera system.
2. Description of the Prior Art
Many computer vision applications involve transformations between an observed point in the scene and the corresponding point in the camera image. The parameters for this projective transformation are typically derived by establishing correspondences between a small set of points on a known target and their respective images. In a camera-projection system, pixels in the computer display frame are projected onto a flat surface and then observed by a camera. This involves a composition of two transforms: one from the projector to the screen and a second from the screen to the camera.
A known calibration pattern is projected onto a possibly unknown flat surface by a projector with a possibly unknown location, orientation and focal length. An image of this pattern is captured by a camera mounted at a possibly unknown location and orientation and with a possibly unknown focal length. It is necessary then to recover the mapping between a given point in the source (pre-projection) image and its corresponding point in the camera image.
Recovering the parameters of the mapping in the prior art systems requires knowledge of the projector and camera setup. Typically, passive scenes are tradditionally studied in computer vision applications for a projector-camera system. In addition, complete physical models must be derived to create a composition of non-linear distortions.
It is, therefore, an object of the present invention to allow the recovery of the parameters of the mapping without knowledge of the projector and camera setup. It is another object of the present invention to allow the projector-camera system to project known calibration patterns into the scene, unlike the passive scenes traditionally studied in computer vision. It is a further object of the present invention to be modeled as a single projective transform, not requiring the derivation of a complete physical model. It is well known that a projective transform can be completely specified by eight parameters, so it is still a further object of the present invention to automatically recover these parameters.
SUMMARY OF THE INVENTION
In order to overcome the problems with prior art systems, we have developed a method which includes arbitrarily placing a camera and projector in the scene, such that their fields of view intersect a (planar) region on the screen; projecting one or more known calibration patterns on the screen; capturing the images of the calibration pattern(s) by a digital camera; identifying the locations of the features in the calibration pattern(s) in the camera image(s); and, given the locations of a small set of corresponding features in both source and camera frames, utilizing the techniques of linear algebra to obtain the parameters for the mapping. At least four feature points (in one or more patterns) must be visible in the camera image. If more features are available, then the mapping that best fits the data (in a least-squares sense) is found.
We have also developed an apparatus that is capable of performing the above-described method.
REFERENCES:
patent: 4111536 (1978-09-01), Taylor
patent: 4185918 (1980-01-01), DiMatteo et al.
patent: 4372655 (1983-02-01), Matsumura et al.
patent: 4621292 (1986-11-01), Hirao et al.
patent: 4682214 (1987-07-01), Sato et al.
patent: 4754329 (1988-06-01), Lindsay et al.
patent: 4843410 (1989-06-01), Kallenberg
patent: 4988187 (1991-01-01), Kuriyama
patent: 4988856 (1991-01-01), Hamada et al.
patent: 5159378 (1992-10-01), Takada et al.
patent: 5216504 (1993-06-01), Webb et al.
patent: 5231481 (1993-07-01), Eouzan et al.
patent: 5255045 (1993-10-01), Nonaka
patent: 5274362 (1993-12-01), Potvin
patent: 5276523 (1994-01-01), Kurematsu et al.
patent: 5278602 (1994-01-01), Honna et al.
patent: 5298993 (1994-03-01), Edgar et al.
patent: 5321494 (1994-06-01), Donahue et al.
patent: 5329310 (1994-07-01), Liljegren et al.
patent: 5339154 (1994-08-01), Gassler et al.
patent: 5363318 (1994-11-01), McCauley
patent: 5369432 (1994-11-01), Kennedy
patent: 5371537 (1994-12-01), Bohan et al.
patent: 5373343 (1994-12-01), Nonaka
patent: 5381349 (1995-01-01), Winter et al.
patent: 5475447 (1995-12-01), Funado
patent: 5483259 (1996-01-01), Sachs
patent: 5499040 (1996-03-01), McLaughlin et al.
patent: 5502458 (1996-03-01), Braudaway et al.
patent: 5561459 (1996-10-01), Stokes et al.
patent: 5570108 (1996-10-01), McLaughlin et al.
patent: 5614925 (1997-03-01), Braudaway et al.
patent: 5619349 (1997-04-01), Ueda et al.
patent: 5638117 (1997-06-01), Engeldrum et al.
patent: 5734938 (1998-03-01), Hamada et al.
patent: 5739809 (1998-04-01), McLaughlin et al.
patent: 5742698 (1998-04-01), Minami et al.
patent: 5786803 (1998-07-01), Hernandez et al.
patent: 5792147 (1998-08-01), Evans et al.
patent: 5793340 (1998-08-01), Morita et al.
patent: 5803570 (1998-09-01), Chen et al.
patent: 6115022 (2000-09-01), Mayer, III et al.
patent: 6219099 (2001-04-01), Johnson et al.
patent: 6292171 (2001-09-01), Fu et al.
patent: 6331848 (2001-12-01), Stove et al.
patent: 6346933 (2002-02-01), Lin
patent: 6483555 (2002-11-01), Thielemans et al.
Faugeras, Olivier, “Three-Dimensional Computer Vision”, The MIT Press, 14 pages, 1992.
Longuet-Higgins, H.C., “A Computer Algorithm for Reconstructing A Scene From Two Projections”, Nature, vol. 293, pp. 133-135, 1981.
Faugeras, O.D. et al., “Motion and Structure from Motion in a Piecewise Planar Environment”, National Journal of Pattern Recognition and Artificial Intelligence, vol. 2, pp. 485-508, 1988.
Tagare, Hemant D., et al., “Simultaneous Estimation of Shape and Reflectance Map from Photometric Stereo”, GIP: Image Understanding, vol. 55, pp. 275-286, 1992.
Hartley, Richard I., “In Defense of the Eight-Point Algorithm,” IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 19, pp. 580-593, 1997.
Lohmann, Adolf W., et al., “Digital Method for Measuring the Focus Error”, Applied Optics, vol. 36, pp. 7204-7209, 1997.
Mullin Matthew
Stockton Robert
Sukthankar Rahul
Justsystem Corporation
Miller John
Natnael Paulos
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
LandOfFree
Method and apparatus for calibrating projector-camera system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for calibrating projector-camera system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for calibrating projector-camera system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3112573