The angle of video camera objective should be around 60° for correct working of the Vehicle Detector module. This condition is defined by the following factors:

  1. there are no geometric distortions of image corresponding to objectives with angle more than 60°;
  2. objective with angle 60° can cover several road lanes by contrast of long-focus objectives.

Location of video cameras is defined by the following interrelating factors while using the Vehicle Detector module:

Geometry of detection zone while using the Vehicle Detector module is presented in the figure. Video camera is located in the point C. Axis Y is align with video camera pier. Axis X is directed along a road against the current of traffic. Axis Z is perpendicular to a road. Lane of vehicles moving is presented by dashed line. Center of detection zone is presented by point b.

Size of detection zone is selected the following way:

  1. length of zone is 6 meters.
  2. width of zone is about 2 meters.

Width of detection zone can be varied to reduce covering effect of vehicles moving by neighboring lanes.

Covering effect of vehicles moving by neighboring lanes is missing if video camera is located strictly above the center of detection zone ("top view to lane").

In such case point b will coincide with origin of coordinates (see figure).

In other cases covering effect is observed especially for large vehicles.

The lower a video camera pier and the longer its location from center of zone by axis Z, the more significant a covering effect.

It is recommended to mount video camera the following way:

  1. minimal height of video camera suspension is about 8 meters;
  2. pier should be located as close to the zone center by axis Z as possible.

It is recommended to mount objective axis perpendlcularly to road to minimize value of accuracy error.