System and method for counting cars at night
First Claim
1. A traffic monitoring system comprising:
- a video processor that is configured to receive an image from a camera having a field of view that includes a roadway, anda pattern recognizer that is configured to identify headlight patterns in a recognition zone within the image, and to thereby distinguish vehicles within the recognition zone;
whereinthe vehicles include headlights that are characterized as producinga broad segment of projected light anda narrower segment of higher intensity light;
the recognition zone corresponds to a segment of a field of view of the camera wherein reflected light received from reflection areas that are illuminated by the narrower segment of higher intensity light is substantially diminished andthe projected light from the headlights is received directly; and
the headlight patterns correspond to the projected light from the headlights wherein the pattern recognizer distinguishes by counting only newly identified vehicles within the recognition zone.
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Accused Products
Abstract
A vehicle identification system distinguishes vehicles in reduced visibility conditions based on the characteristic projection patterns associated with vehicle headlights and their reflections. Recognizing that the appearance of reflections of headlight beams in a camera image is highly dependent upon the angle of incidence/reflection relative to the camera, whereas the appearance of the headlights in the camera image is relatively consistent, the vehicle identification system distinguishes vehicles from their reflections based on the tracks of the illumination patterns in a series of images. In a first embodiment, headlights are distinguished from reflections based on a length of the tracks. In a second embodiment, recognition zones are selected as regions in the camera image that are not likely to provide reflections from normally aligned headlight beams. Pattern-matching and motion-correlation techniques are also used to identify the track of each vehicle in prior and subsequent image frames.
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Citations
32 Claims
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1. A traffic monitoring system comprising:
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a video processor that is configured to receive an image from a camera having a field of view that includes a roadway, and a pattern recognizer that is configured to identify headlight patterns in a recognition zone within the image, and to thereby distinguish vehicles within the recognition zone; wherein the vehicles include headlights that are characterized as producing a broad segment of projected light and a narrower segment of higher intensity light; the recognition zone corresponds to a segment of a field of view of the camera wherein reflected light received from reflection areas that are illuminated by the narrower segment of higher intensity light is substantially diminished and the projected light from the headlights is received directly; and the headlight patterns correspond to the projected light from the headlights wherein the pattern recognizer distinguishes by counting only newly identified vehicles within the recognition zone. - View Dependent Claims (2, 3, 4, 5, 6, 7, 17, 18, 19, 20)
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8. A method of detecting a vehicle, comprising:
receiving an image from a camera having a field of view that includes a roadway, identifying one or more headlight patterns within a recognition zone of the image, detecting the vehicle based on the one or more headlight patterns; and
counting only newly identified vehicles within the recoanition zone whereinthe vehicle includes headlights that are characterized as producing a broad segment of projected light and a narrower segment of higher intensity light; and the recognition zone corresponds to a segment of the field of view of the camera wherein reflected light received from a reflection area of the roadway that is illuminated by the narrower segment of higher intensity light is substantially diminished, and the projected light is received directly. - View Dependent Claims (9, 10, 11, 12, 13, 21, 22, 23, 24)
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14. A computer program embodied on a computer readable medium for execution on a processing device that causes the processing device to:
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identify illumination patterns in a series of images from a video camera, determining a length of tracks of the illumination patterns in the series of images and distinguish vehicles from reflections by comparing the determined length of the tracks of the illumination patterns in the series of images with a threshold value. - View Dependent Claims (15, 16)
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25. A traffic monitoring system comprising:
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a video processor that is configured to receive a sequence of images from a camera having a field of view that includes a roadway, a tracking system that is configured to identify determine a length of tracks of illumination patterns within the sequence of images, and a reflection detector that is configured to distinguish illumination patterns that correspond to reflections, by comparing the determined length of the tracks of the illumination patterns with a threshold value. - View Dependent Claims (26, 27, 28)
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29. A method of detecting vehicles, comprising:
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maintaining one or more tracks corresponding to a series of consistent illumination patterns from a series of images from a video camera, determining a length of the one or more tracks with a threshold value, and distinguishing each illumination pattern corresponding to each vehicle from each illumination pattern corresponding to each reflection from each vehicle by comparing the determined length of each of the one or more tracks with a threshold value. - View Dependent Claims (30, 31, 32)
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Specification