How to Consistently Capture License Plate Data

How to Get Good Results when Trying to Capture License Plates

1. Angle

An ALPR camera's license plate performance, such as our Specialist model, is directly tied to the height, angle, and distance, where it is installed.

You want to have no more than a 15° offset, both horizontally and vertically. Plates should be as direct/inline to the camera as possible. If the angle is incorrect, it will result in missed captures or incorrect plate readings.

2. Vibration

The Specialist, and many other ANPR cameras, have very powerful zoom lenses, and when zooming in on any camera, movements such as vibrations, wind, etc., will be much more apparent than with a standard wide/normal lens camera.

Take proper precautions to install this camera on a stable surface that doesn’t transfer vibrations. If you are mounting this camera on a pole, be sure the pole is sufficiently stable and does not introduce vibrations.

3. Zoom Level

Instead of using just one set of settings for saturation, brightness, contrast, and sharpness levels, Wide Dynamic Range splits each frame/image into many sections and determines the correct exposure to create a consistent and balanced image. WDR is very useful when recording in situations where different areas of the same scene are going to have varied lighting levels. Most situations where you want to record license plates are going to have these light variations because of headlights and street lamps.

4. Speed of Vehicle

The Specialist camera is rated for 15MPH maximum speed. Vehicles over 15 MPH are unlikely to capture correctly.

The Specialist is designed primarily for entry/exit point applications. SCW ideally suggests aiming at stop signs or slow down points like speed bumps or gates.

5. Back Plates vs Front Plates

SCW strongly recommends planning your license plate solution to capture the back of vehicles / back plates rather than front plates.

- Many states do not require front plates. Even if your state requires them, out of state visitors may not have them.
- Back plates are lit - and significantly easier to get correctly at night
- Front plates are not lit - and have bright headlights
- This will require careful placement considerations (height, angle, elevation)
- As well as significant image setting tweaks for various vehicle heights
- These issues are especially important at night.
- Additional lighting in the area may be required for front plates