Based On Video Traffic Detection Technology Application In Hanghui Highway

The detecting system of highway traffic flow is a sort of intelligent traffic detecting system which based on video. It adopts the technologies for digital image processing and computer vision.In this thesis, we analyze the principle of traffic flow detecting based on video and introduce the relevant knowledge about digital image processing and computer vision. And to study on camera demarcation, background updating, target identification and traffic flow parameter detection.A certain noises often exist in the video image for various reasons like surroundings, equipment performance, etc. so it is required to preprocess the input video image. Through comparison of different image processing methods, neighborhood averaging method is selected to do image filtering considering the need of real-time processing. Then edge detection is made by means of combining Laplacian with SOBEL operator. After preprocessing, the image can meet the need of further processing well.Camera demarcation is aimed to figure out the corresponding relation between the coordinate system of camera image and the three-dimensional reference coordinate system of object space. Through analysis and comparison of present various demarcation methods, a demarcation method for camera based on orthogonal transform is brought forth. It removes the anamorphic effect of perspective well by transforming the perspective coordinate system to the orthogonal one.Background innovation is the basis of traffic flow parameter detection. In this thesis, a background updating method based on the grayscale frequency statistics is used to analyze the video image data collected by fixed camera. At the same time, the foreground image is captured by means of background difference algorithm.The main part of video traffic parameter detection is Car detection. Through various algorithm, a new image matching algorithm based on coherence theory is brought forth to detect the vehicle speed. And a car flow detection algorithm based on virtual detection line is designed on this basis. Good result is obtained when simulating this algorithm by Matlab software.