VIS-CAM System
2 Preparing for installation
2.1 Installation Preparation
To prepare for installation, consider the fundamental requirements for an effective deployment of the Vehicle Imaging Subsystem. There are two basic ways to position the camera: over the lane or beside the lane. Figure 3 and Figure 4 depict a typical
2.1.1Over Lane Positioning
Over lane camera mounting is always employed when the road width being monitored contains more than two lanes of traffic, when a convenient overhead structure is already in place, or when preventing vandalism is a paramount concern.
The VIS’s varifocal (zoom) lens is adjusted during installation to create 135 pixels across a 1 foot wide license plate (standard for US style of plates, may differ by region) placed 2 feet above the ground level at the nominal trigger position (loop or light curtain, etc.). This resolution maximizes license plate reader, vehicle matcher, or other image processing techniques performance. The highest performance from the subsystem is achieved when the variation in plate size is kept to within ± 5% which typically means that the vehicle trigger accuracy should be within ± 1 foot (@ trigger plane defined by client.) at all speeds. Low latency vehicle triggering is very important and should not be overlooked. Please contact JAI for support on this issue.
Figure 3. Typical Over Lane Site Layout
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