Image forming and processing device and method for use with no moving parts camera
First Claim
1. A method of video surveillance comprising the steps of:
- providing a video camera having an image plane and a fisheye lens, the fisheye lens having a lens constant indicative of distortion caused by the fisheye lens, a primary axis and a substantially hemispheric field of view and the camera having an image plane, the image plane having a center point through which the primary axis passes;
mounting the camera at a mounting point vertically above a surveillance plane such that the primary axis of the fisheye lens lies substantially perpendicular to the surveillance plane;
causing the video camera to form a fisheye image, the fisheye image being distorted by the fisheye lens and comprising a plurality of pixels, each pixel having unique fisheye coordinates;
generating a corrected image of sub-area in the field of view by the steps of;
providing angular coordinates of an object in the field of view by simulating a hypothetical camera having a hypothetical axis and such that the hypothetical axis passes through the center point and the object in the field of view at specific pan and tilt angles;
selecting an area of the fisheye image, wherein the area comprises a subset of the plurality of pixels, each pixel of the subset being displaced from the specific pan angle by an angle "a";
determining the unique fisheye coordinates of each pixel of the subset of the plurality of pixels by means of a formula comprising the lens constant, the specific tilt angle "b" and the angle "a", said formula being given by
space="preserve" listing-type="equation">X.sub.d =f.cos.sup.-1 (cos(a).cos(b)).cos(tan.sup.-1 (tan(a)/sin(b)))
space="preserve" listing-type="equation">Y.sub.d =f.cos.sup.-1 (cos(a).cos(b)).sin(tan.sup.-1 (tan(a)/sin(b))), where "f" is the lens constant and Xd and Yd are the unique fisheye coordinates; and
mapping the pixels in the subset of the plurality of pixels to normal coordinates, thereby forming the corrected image of the sub-area.
4 Assignments
0 Petitions
Accused Products
Abstract
A video surveillance system has a camera equipped with a fisheye lens having a substantially hemispheric field of view. The system implements operations equivalent to the panning, tilting and zooming of a conventional camera without the use of moving parts. The lens is mounted vertically above a plane under surveillance. The camera produces a fisheye image made up of a plurality of pixels. The fisheye image is distorted due to the properties of the fisheye lens. The system corrects the distortion by mapping the pixels of the fisheye image to coordinates produced by selecting a particular part of the fisheye image to be viewed. This allows an operator to select parts of the field of view of the fisheye lens and view them as if they had been produced by a camera having a conventional lens being panned tilted or zoomed. The fisheye image formed by the camera is split into four separate image components carried by four bundles of optical fibers. Each bundle has a CCD and associated image processing circuitry which forms an electronic representation of the image component carried by that bundle.
93 Citations
11 Claims
-
1. A method of video surveillance comprising the steps of:
-
providing a video camera having an image plane and a fisheye lens, the fisheye lens having a lens constant indicative of distortion caused by the fisheye lens, a primary axis and a substantially hemispheric field of view and the camera having an image plane, the image plane having a center point through which the primary axis passes; mounting the camera at a mounting point vertically above a surveillance plane such that the primary axis of the fisheye lens lies substantially perpendicular to the surveillance plane; causing the video camera to form a fisheye image, the fisheye image being distorted by the fisheye lens and comprising a plurality of pixels, each pixel having unique fisheye coordinates; generating a corrected image of sub-area in the field of view by the steps of; providing angular coordinates of an object in the field of view by simulating a hypothetical camera having a hypothetical axis and such that the hypothetical axis passes through the center point and the object in the field of view at specific pan and tilt angles; selecting an area of the fisheye image, wherein the area comprises a subset of the plurality of pixels, each pixel of the subset being displaced from the specific pan angle by an angle "a"; determining the unique fisheye coordinates of each pixel of the subset of the plurality of pixels by means of a formula comprising the lens constant, the specific tilt angle "b" and the angle "a", said formula being given by
space="preserve" listing-type="equation">X.sub.d =f.cos.sup.-1 (cos(a).cos(b)).cos(tan.sup.-1 (tan(a)/sin(b)))
space="preserve" listing-type="equation">Y.sub.d =f.cos.sup.-1 (cos(a).cos(b)).sin(tan.sup.-1 (tan(a)/sin(b))),where "f" is the lens constant and Xd and Yd are the unique fisheye coordinates; and mapping the pixels in the subset of the plurality of pixels to normal coordinates, thereby forming the corrected image of the sub-area. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
Specification