This paper presents an open-source software application for analyzing traffic camera footage, focusing on vehicle behavior and braking events at signalized urban highways. The core innovation is a robust ground-plane homography estimation that links fixed traffic camera views to satellite orthoimagery. This process rectifies the camera's oblique perspective, ensuring that pixel distances accurately represent real-world distances. This enables the acquisition of features such as vehicle trajectory, speed, deceleration, and braking severity without the need for camera calibration. The pipeline employs the MAGSAC++ estimator to build the homography, converting YOLO11 object detections into a rectified top-down coordinate system. All detection and trajectory data are stored in a ClickHouse database for subsequent analysis. A real-world case study at two signalized intersections in Key West, Florida, showcased the system's capabilities. Across two days of daytime footage, braking activity at the higher-volume intersection peaked around 4 PM at approximately 57.5 events per hour, while the second intersection peaked around 10 AM at roughly 15.5 events per hour. The spatial analysis revealed that most braking events initiated upstream, with mild and moderate braking mostly occurring 30 to 45+ meters away from the stop bar and severe braking distributed throughout, but particularly concentrated in lanes with higher interaction and merging activity. The findings highlight the significant potential of this centralized safety information system to support connected vehicles, facilitating proactive traffic management, crash mitigation, and data-driven roadway design and safety analysis.

翻译：本文提出一种用于分析交通监控视频的开源软件应用，重点关注城市信号控制高速公路上的车辆行为与制动事件。其核心创新在于一种鲁棒的地平面单应性估计方法，能够将固定交通摄像头的视角与卫星正射影像进行关联。该过程校正了摄像头的倾斜透视，确保像素距离能够精确反映真实世界距离。这使得无需摄像头标定即可获取车辆轨迹、速度、减速度及制动严重程度等特征。处理流程采用MAGSAC++估计器构建单应性矩阵，将YOLO11目标检测结果转换至校正后的俯视坐标系。所有检测与轨迹数据均存储于ClickHouse数据库中以供后续分析。通过在佛罗里达州基韦斯特市两个信号控制交叉口的实际案例研究，展示了该系统的能力。在为期两天的日间视频数据中，高流量交叉口的制动活动在下午4点左右达到峰值，约为每小时57.5次事件；而第二个交叉口则在上午10点左右达到峰值，约为每小时15.5次事件。空间分析表明，大多数制动事件始于上游区域，轻度与中度制动多发生在距离停车线30至45米以远的位置，而严重制动事件则分布较广，尤其集中于车辆交互与合流活动更频繁的车道。研究结果凸显了这种集中式安全信息系统在支持网联车辆、促进主动交通管理、事故缓解以及数据驱动的道路设计与安全分析方面的巨大潜力。