![background image](http://html1.mh-extra.com/html/jai/vis-cam-system/vis-cam-system_installation-manual_3223355018.webp)
VIS-CAM Systems
6
Preparing for Installation
Figure 4.
Typical Over Lane Site Layout Plan.
2.1.1 (a) Camera tilt considerations
The requirement to freeze the motion of high-speed vehicles limits how steep or shallow the tilt angle of the
camera may be. For example, it is important to prevent the horizon from appearing in the image, and thereby
allowing the sun to blind the camera. For over lane installations, a camera tilt between 20° to 30° is
recommended–with 25° being considered the optimal angle. This angle of tilt is the best compromise between
minimizing visibility blockages caused by closely spaced vehicles and maximizing plate visibility for plate
mounts that are slightly recessed or tilted downwards.
2.1.1 (b) Asynchronous triggering considerations
When the VIS is operated in trigger mode, a vehicle detector is employed to cause the camera to capture an
image at the precise moment the vehicle is in the best position to image both the vehicle and its license plate.
The delay between the time the vehicle passes the trigger position on the road and when the trigger signal
actually reaches the VIS must be kept to a minimum to prevent high-speed vehicles from moving out of the
area viewed by the camera before the image is snapped.
2.1.1 (c) Camera height versus trigger distance considerations
It is critically important, to select the correct distance between the camera and the location on the road where
the camera is triggered to capture an image. Minimizing the cost of installation is usually also an important
concern. This means that whenever possible, it is best to use existing structures or previously installed
elements. The following charts (Figures 5 to 12) provide a wide range of trade-offs between camera height and
trigger distance to enable the installer to select convenient camera and light sensor locations relative to
existing mounting structures and vehicle trigger locations. Adhering to the installation options provided in the
installation charts, yields camera images that are generally suitable for automatic license plate readers (ALPR).
To use the charts correctly, please follow the steps below.
1.
First measure the height above the road to convenient camera mounting locations.
2.
Measure the distance along the road from directly beneath each candidate camera position to
convenient trigger locations.
3.
Select the appropriate installation chart for either USA or European style license plates. To
obtain charts for license plates from other countries, please contact the JAI ITS division directly
at (+1) 408 383 0300.
Summary of Contents for VIS-CAM System
Page 1: ...VIS CAM System Vehicle Imaging Subsystem Document Version 10436 Document P N E...
Page 2: ......
Page 12: ...VIS CAM Systems xii List of Tables...
Page 20: ...VIS CAM Systems 8 Preparing for Installation Figure 5 VIS 300 U S Camera options chart...
Page 21: ...Preparing for Installation 9 VIS CAM Systems Figure 6 VIS 350 U S Camera options chart...
Page 22: ...VIS CAM Systems 10 Preparing for Installation Figure 7 VIS 400 U S Camera options chart...
Page 23: ...Preparing for Installation 11 VIS CAM Systems Figure 8 VIS 500 U S Camera options chart...
Page 24: ...VIS CAM Systems 12 Preparing for Installation Figure 9 VIS 300 European Camera options chart...
Page 25: ...Preparing for Installation 13 VIS CAM Systems Figure 10 VIS 350 European Camera options chart...
Page 26: ...VIS CAM Systems 14 Preparing for Installation Figure 11 VIS 400 European Camera options chart...
Page 27: ...Preparing for Installation 15 VIS CAM Systems Figure 12 VIS 500 European Camera options chart...
Page 92: ...VIS CAM Systems 80 Appendix B Figure 90 Lane controller setup...
Page 100: ...VIS CAM Systems 88 Appendix E Figure 98 Operation configuration of Serial port 1...
Page 110: ......
Page 111: ......