Method and apparatus for measuring traffic flow
First Claim
1. A traffic measurement method comprising the steps of:
- obtaining image information of a plurality of sampling points in a measurement area set on a road using an ITV camera mounted to view the road;
effecting spatial differentiation based on brightness information contained in the image information of the sampling points to detect an edge portion of a running vehicle as well as a stopped vehicle;
binarizing the brightness information of the sampling points by comparing differentiation signals derived from the spatial differentiation with a predetermined threshold;
masking pixels detected as the edge portion of the binary image derived from the binarization with mask patterns respectively having a width corresponding to vehicle types;
selecting one of the mask patterns having a width in correspondence with a type of the running vehicle;
selecting one or more candidate points for a vehicle front as one or more pixels at a center of gravity of the pixels of the edge portion present in the selected mask pattern;
determining a vehicle front point at a first predetermined time from the candidate points selected within the measurement area; and
calculating a vehicle velocity based on a distance that the vehicle front point has moved in a predetermined time period from said first predetermined time.
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Abstract
This invention aims at providing an traffic flow measurement method and apparatus attaining the stable measurement without being affected by the change in the brightness of the external environment such as daytime vehicle front, et al. In order to achive the above object, the traffic flow measurement apparatus for practicing the traffic flow measurement method comprises image input unit for receiving image information derived from the ITV camera, detection unit for detecting sampling points which are candidates for a vehicle fronts in a measurement area, and measurement processing unit for determining a position of the vehicle front in the measurement area from the candidate points detected by the detection unit. The measurement processing unit calculates a vehicle velocity based on a change between a position of the vehicle front derived from past image information and a current position of the vehicle front.
45 Citations
18 Claims
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1. A traffic measurement method comprising the steps of:
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obtaining image information of a plurality of sampling points in a measurement area set on a road using an ITV camera mounted to view the road; effecting spatial differentiation based on brightness information contained in the image information of the sampling points to detect an edge portion of a running vehicle as well as a stopped vehicle; binarizing the brightness information of the sampling points by comparing differentiation signals derived from the spatial differentiation with a predetermined threshold; masking pixels detected as the edge portion of the binary image derived from the binarization with mask patterns respectively having a width corresponding to vehicle types; selecting one of the mask patterns having a width in correspondence with a type of the running vehicle; selecting one or more candidate points for a vehicle front as one or more pixels at a center of gravity of the pixels of the edge portion present in the selected mask pattern; determining a vehicle front point at a first predetermined time from the candidate points selected within the measurement area; and calculating a vehicle velocity based on a distance that the vehicle front point has moved in a predetermined time period from said first predetermined time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A traffic flow measurement apparatus comprising:
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an ITV camera for picking up an image of a measurement area set in view of a road; an image input unit for receiving brightness information of sampling points included in the image information of said ITV camera; a detection unit for detecting a vehicle front based on the image information from said image input unit, wherein said detection unit, effects spatial differentiation based on brightness information contained in the image information of the sampling points to detect an edge portion of a running vehicle as well as a stopped vehicle, binarizes the brightness information of the sampling points by comparing differentiation signals derived from the spatial differentiation with a predetermined threshold, masks pixels detected as the edge portion of the binary image derived from the binarization with mask patterns respectively having a width corresponding to vehicle types, selects one of the mask patterns having a width in correspondence with a type of the running vehicle, and selects one or more candidate points for the vehicle front as one or more pixels at a center of gravity of the pixels of the edge portion present in the selected mask pattern; and a measurement processing unit, said measurement processing unit determines a vehicle front point at a predetermined time from the candidate points in the measurement area, and calculates a vehicle velocity based on a distance that the vehicle front point has moved in a predetermined time period. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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Specification