【作者】 于渊；

【导师】 杨兆选；

【作者基本信息】 天津大学 ， 信号与信息处理， 2007， 硕士

【摘要】 智能交通系统是国内外的热点研究领域,其中基于视频的交通信息采集与检测技术因其简单、方便、实时性好越来越受到重视。论文工作所研究的交通信息检测系统,利用架设在路面上方的摄像机获取道路现场图像,通过视频采集卡对现场图像进行处理,提取交通信息,最后将现场图像和交通信息参数上传至监控中心。这样,通过基于视频的方法实现了交通信息的检测,这对道路交通的智能化管理有着重要意义。本文研究了基于DSP的视频交通信息检测系统的架构,对作为系统核心的视频采集卡的硬件结构进行了深入研究。详细介绍了模拟视频信号接入采集卡以后的信号处理过程,即视频信号的模数转换,视频流的缓冲,时序控制,DSP对视频流的处理显示等。系统中,还涉及到需要将图像中车辆行驶的象素距离转换为实际行驶的道路距离,这就必须利用摄像机定标算法来完成图像坐标系向世界坐标系的转换。在深入研究对比各种定标算法的基础上,提出了基于直接线性变换的摄像机定标算法,通过最小二乘迭代的方法对该算法进行解算,最后通过三维重建,实现了坐标转换。对算法MATLAB仿真结果进行分析,可以看出该转换算法求解简单且具有较高的定位精度,能够满足视频交通信息检测系统的定标精度要求。该算法已实际应用于交通信息检测系统的车辆速度检测的程序设计。采用本文所研究的视频检测卡和摄像机定标算法的视频交通信息检测系统经过道路现场实验表明:该视频检测系统能够有效地提取车速,占有率,车流量等交通信息并且具有较高的检测精度和很好的实时性。更多还原

【Abstract】 The research on intelligent transport system is always very hot all over the world. Among them, video-based traffic information acquisition and detection is being attached more and more importance because of its simplicity、convenience and real-time characteristic.In this paper the camera set above the road is used to collect the road images. Then traffic information is obtained by image processing by the video acquisition board. Finally these parameters and video are uploaded to the surveillance center. Thus by using video-based method the traffic parameters detection is realized, which is very important to traffic intelligent management.On the basis of the research of the DSP-based detection system, the deep research on the video acquisition board– core of the system—is presented. Beginning from the analog video signal input, the following aspects are introduced in detail: video A/D, video cache, timing control, image processing by DSP and so on.In the system, the pixel distance is necessarily converted to the actual road distance. Therefore camera calibration is applied to the conversion from image coordinates to world coordinates. After reviewing all kinds of calibration methods, an algorithm based on Direct Linear Transform (DLT) is presented, whose calculation is accomplished by the least square iteration and the conversion is realized by 3-D reconstruction. Based on the anlysis of MATLAB simulation results,it is concluded that the algorithm has the advantage of high-accuracy and its parameters can be easily estimated. It is proved that the algorithm could meet the requirement of calibration accuracy in the application of the video-based traffic information detection. The algorithm is finally applied to vehicle velocity detection program.The detection system adopting video acquisition board and camera calibration algorithm is tested on real-world scenes and experimental results prove that the system can effectively aquisite the traffic parameters such as the velocity、occupation ratio and car flow quantity. Real-time detection and high accuracy is achieved.更多还原