Influence of camera properties on image analysis in visual tunnel surveillance

CCTV and image analysis systems for automatic incident detection are major tools in tunnel safety management. This paper presents results of a feasibility study called VITUS-1. Among others, one aim of VITUS-I was to compare image analysis methods for robust object detection, tracking and incident detection. Image quality improvements were shown by using digital camera technology instead of state-of-the-art analogue CCTV. To improve image quality and robustness of existing image analysis methods, requirements on several camera properties were defined. We want to sensitise primarily tunnel operators and tunnel CCTV experts that commercial image analysis systems usually do not claim such requirements, e.g. requirements on resolution. This paper shows with a simple camera model that a robust detection of test objects is hardly feasible with typical tunnel CCTV (PAL resolution, 20° viewing angle, 212m camera distance). As a consequence, the specifications of tunnel CCTV should be adjusted to the needs of image analysis systems. Simple experiments with real video data show the applicability of the camera model.