Method for presenting fisheye-camera images
First Claim
1. A method for presenting fisheye-camera images, which employs a plurality of known optical parameters comprising a principal point, a focal length constant and a projection function obtained from a parameterized fisheye camera in order to transform an original image shot by the parameterized fisheye camera into a transformed image, the method comprises:
- calculating a principal distance ρ
between an imaged point and the principal point in the original image and defining an azimuthal distance β
of the imaged point;
deriving a zenithal distance α
of the imaged point according to the principal distance ρ
, the focal length constant and the projection function;
normalizing the imaged point onto a small sphere as a normalized imaged point according to the zenithal distance α and
the azimuthal distance β
; and
projecting the normalized imaged point onto a projection surface as a transformed imaged point by means of a map projection in cartography in order to form the transformed image.
1 Assignment
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Accused Products
Abstract
The present invention is a method for presenting the fisheye-camera images. A calibration target with a concentric-and-symmetric pattern (PCT) is utilized to assist in parameterizing a fisheye camera (FIS) in order to ascertain the optical parameters comprising the principal point, the focal length constant and the projection function of the FIS. Hence, the position of an imaged point referring to the principal point on the image plane directly reflects its corresponding zenithal distance α and azimuthal distance β of the sight ray in space so as to normalize the imaged point onto a small sphere. Further according to the map projections in cartography capable of transforming the global geometry into flap maps, the interesting area in a field of view can be accordingly transformed by a proper projection method. The image transforming method disclosed in the invention is simple, low-cost, suitable to various FISs with different projection mechanisms and capable of transforming the fisheye-camera images for particular functions, such as the approach of normal human visual perception, video data encryption, and image compression/transformation with a high fidelity.
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Citations
28 Claims
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1. A method for presenting fisheye-camera images, which employs a plurality of known optical parameters comprising a principal point, a focal length constant and a projection function obtained from a parameterized fisheye camera in order to transform an original image shot by the parameterized fisheye camera into a transformed image, the method comprises:
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calculating a principal distance ρ
between an imaged point and the principal point in the original image and defining an azimuthal distance β
of the imaged point;
deriving a zenithal distance α
of the imaged point according to the principal distance ρ
, the focal length constant and the projection function;
normalizing the imaged point onto a small sphere as a normalized imaged point according to the zenithal distance α and
the azimuthal distance β
; and
projecting the normalized imaged point onto a projection surface as a transformed imaged point by means of a map projection in cartography in order to form the transformed image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for presenting fisheye-camera images, which employs a plurality of known optical parameters comprising a principal point, a focal length constant and a projection function obtained from a parameterized fisheye camera in order to transform an imaged point into a normalized imaged point, the method comprises:
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calculating a principal distance ρ
which is the distance between the imaged point and the principal point in an original image shot by the parameterized fisheye camera and defining an azimuthal distance β
corresponding to the imaged point;
deriving a zenithal distance α
corresponding to the imaged point according to the principal distance ρ
, the focal length constant and the projection function; and
normalizing the imaged point onto a small sphere as the normalized imaged point according to the zenithal distance α and
the azimuthal distance β
. - View Dependent Claims (12, 13, 14)
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15. A method for presenting fisheye-camera images, which employs a plurality of known optical parameters comprising a principal point, a focal length constant and a projection function obtained from a parameterized fisheye camera in order to transform an original image shot by the parameterized fisheye camera into a panorama, the method comprises:
-
calculating a principal distance ρ
between an imaged point and the principal point in the original image and defining an azimuthal distance β
of the imaged point;
deriving a zenithal distance α
of the imaged point according to the principal distance ρ
, the focal length constant and the projection function;
normalizing the imaged point onto a small sphere as a normalized imaged point according to the zenithal distance α and
the azimuthal distance β
; and
projecting the normalized imaged point onto a cylindrical surface as a transformed imaged point by means of a gnomonic projection in cartography in order to form the panorama. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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22. A method for presenting fisheye-camera images, which employs a plurality of known optical parameters comprising a principal point, a focal length constant and a projection function obtained from a parameterized fisheye camera in order to transform an original image shot by the parameterized fisheye camera into a perspective-corrected image, the method comprises:
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calculating a principal distance ρ
between an imaged point and the principal point in the original image and defining an azimuthal distance β
of the imaged point;
deriving a zenithal distance α
of the imaged point according to the principal distance ρ
, the focal length constant and the projection function;
normalizing the imaged point onto a small sphere as a normalized imaged point according to the zenithal distance α and
the azimuthal distance β
; and
projecting the normalized imaged point onto a plane as a transformed imaged point by means of a gnomonic projection in cartography in order to form the perspective-corrected image. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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Specification