METHOD AND SYSTEM FOR MEASURING VEHICLE SPEED BASED ON MOVEMENT OF VIDEO CAMERA
First Claim
1. A method for measuring movement of a video camera placed on a moving vehicle, the method comprising:
- (a) acquiring, by the video camera, a video data of the earth surface;
(b) transforming the video data into a sequence of digital frames;
(c) correcting perspective distortions of each digital frame;
(d) finding a correlation of adjacent frames, wherein frame images have maximum coincidence; and
(e) measuring off-set value between the adjacent frames, wherein;
time intervals between the adjacent frames are measured;
camera angle, camera field of view and camera height above the earth surface are recorded at a time of generation of each frame;
a simplified image frame is created for each image frame by approximation and filtering of the image frame;
perspective distortions are corrected for each simplified image frame based on the camera angle, the camera field of view and the camera height above the surface;
correlation of adjacent simplified frames, wherein frame images having maximum coincidence are found;
correction off-set value is calculated based on changes in the camera angle during generation of the image frames corresponding to the simplified image frames; and
an actual off-set of portion of the surface is calculated based on the off-set of the adjacent simplified image frames corrected by the correction off-set value.
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Accused Products
Abstract
A digital video camera is placed on a vehicle. The video camera is attached to the vehicle and is directed to a surface at a certain angle to the surface. The camera angle can change while vehicle is in motion. The camera angle is constantly measured by angular sensor (i.e., inclinometer). Images of the surface are projected onto a video matrix and transformed into a sequence of digital frames that are formed at a pre-set time interval. A speed of the video camera relative to the surface is calculated as a ratio of an off-set between the adjacent frames and the time interval between the frames. Then a known relative speed of the vehicle can be corrected by multiplication of the height of the camera (above the surface) by a coefficient that equals a ratio of the known vehicle speed and the measured camera speed.
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Citations
16 Claims
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1. A method for measuring movement of a video camera placed on a moving vehicle, the method comprising:
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(a) acquiring, by the video camera, a video data of the earth surface; (b) transforming the video data into a sequence of digital frames; (c) correcting perspective distortions of each digital frame; (d) finding a correlation of adjacent frames, wherein frame images have maximum coincidence; and (e) measuring off-set value between the adjacent frames, wherein; time intervals between the adjacent frames are measured; camera angle, camera field of view and camera height above the earth surface are recorded at a time of generation of each frame; a simplified image frame is created for each image frame by approximation and filtering of the image frame; perspective distortions are corrected for each simplified image frame based on the camera angle, the camera field of view and the camera height above the surface; correlation of adjacent simplified frames, wherein frame images having maximum coincidence are found; correction off-set value is calculated based on changes in the camera angle during generation of the image frames corresponding to the simplified image frames; and an actual off-set of portion of the surface is calculated based on the off-set of the adjacent simplified image frames corrected by the correction off-set value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A system for measuring movement of a vehicle, the system comprising:
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a video camera placed on the vehicle for generating digital images of an earth surface, wherein the video camera changes its angle relative to the earth surface as the vehicle moves over the earth surface; a processing unit connected to the camera for processing video image data; and a device for measuring camera angles relative to the earth surface, wherein the processing unit approximates and filters the video image data and calculates off-sets of earth surface images caused by changes in the camera angles relative to the earth surface.
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Specification