Accurate turning movement counts at intersections are important for signal control, traffic management and urban planning. Computer vision systems for automatic turning movement counts typically rely on visual analysis in the image plane of an infrastructure camera. Here we explore potential advantages of back-projecting vehicles detected in one or more infrastructure cameras to the ground plane for analysis in real-world 3D coordinates. For single-camera systems we find that back-projection yields more accurate trajectory classification and turning movement counts. We further show that even higher accuracy can be achieved through weak fusion of back-projected detections from multiple cameras. These results suggeest that traffic should be analyzed on the ground plane, not the image plane

翻译：交叉口转向交通量的精确统计对于信号控制、交通管理和城市规划至关重要。用于自动统计转向交通量的计算机视觉系统通常依赖于基础设施摄像头图像平面内的视觉分析。本文探讨了将单个或多个基础设施摄像头检测到的车辆反投影至地面平面，并在真实世界三维坐标中进行分析的潜在优势。对于单摄像头系统，我们发现反投影能够实现更精确的轨迹分类和转向交通量统计。我们进一步证明，通过对多摄像头反投影检测结果进行弱融合，可以获得更高的准确度。这些结果表明，交通分析应在地面平面而非图像平面上进行。