Calibrating speed estimation - SharpV | SharpOS 12.7

AutoVu Handbook for SharpV Fixed Installations 12.7

series
SharpV | SharpOS 12.7
revised_modified
2019-08-21

For systems that include a fixed SharpV camera, you can configure the camera to include an estimated vehicle speed when performing license plate reads.

Before you begin

  • Install the SharpV camera in a fixed location. To use this feature, cameras should be installed higher than the level of the license plates with respect to the road. This means a camera installation height of at least 1.5 m (5 ft). The camera should be pointing downward with respect to the horizontal by at least 5°.
  • Adjust the zoom and focus of the camera.
    NOTE: If you modify the zoom and focus or the pan and tilt angles of the camera, you must recalibrate speed estimation.
  • Configure the LPR context. Do this so that the speed and measurement units are displayed in the format for your region.

What you should know

  • For more accurate speed estimation, vehicles that pass the camera during calibration should travel at a constant speed of at least 30 km/h (20 mph). This recommendation only applies during calibration. In general, the system can estimate speeds for vehicles moving slower than 30 km/h (20 mph).
  • To calibrate speed estimation, the system needs the following, in any order:
    • At least one license plate read from a calibration vehicle with a known speed. You can do this by driving the calibration vehicle at a specific speed, or by using a radar device to detect the speed of a passing vehicle.
    • 20 additional license plate reads. You do not need to know the speed of these vehicles.
      NOTE: For the calibration to finish quickly, choose a time when vehicles are expected to be traveling in the appropriate direction in the designated area. If no traffic is expected to pass during the calibration, you can use one vehicle to make 20 passes in front of the camera, leaving at least 15 seconds between passes.

Procedure

To configure SharpV speed estimation:

  1. Log on to the SharpV Portal.
  2. From the Configuration menu, select the Analytics > Speed estimation page.
  3. Click Enable.
    The camera saves the configuration and displays the message "Configuration saved successfully".
  4. Click Start calibration.
    The system starts to capture license plate reads for calibration and displays Calibrating…. A counter indicates the number of plate reads remaining to complete the calibration.

If you use a calibration vehicle moving at a specific speed:

  1. From the main speed estimation screen, click Edit.
  2. Click Plate number and enter the license plate of the calibration vehicle.
  3. Click Add.
    The system displays the message: The system is now expecting to read a plate for this vehicle. The vehicle should maintain a constant speed.
    When the system detects the calibration plate, it displays the license plate read with a time stamp.
  4. Click Validate.
    Two images of the calibration plate are displayed.
  5. As shown in the following image, the orange line in each image must follow the bottom of the characters and must be as wide as the license plate. If required, move the end points to correct the line placement.
    IMPORTANT: Speed estimation accuracy depends on precise positioning of the end points.
  6. Enter the Speed at which the vehicle was traveling when it was read by the SharpV camera.
  7. The Width of the plate is entered for you based on the LPR context that you have configured. If necessary, modify the plate width.
  8. (Optional) For more accuracy, measure the distance from the ground to the bottom of the calibration vehicle's license plate and enter the measurement in the Distance from ground to plate field.
  9. Click Validate.
    A green check mark is displayed over the calibration plate, indicating that the step is complete.
    NOTE: You can add plate numbers for additional calibration vehicles. This is not required, but can increase speed estimation accuracy.

If you use a radar device to detect the speed of a passing vehicle:

  1. From the main speed estimation screen, click Edit.
  2. Click Advanced on the right side of the screen.
    The license plates from passing vehicles are displayed.
  3. Take note of the license plate of a passing vehicle and use your radar device to detect the vehicle's speed.
  4. Click the license plate image of the vehicle with the known speed.
    Two images of the calibration plate are displayed.
  5. The orange line on each image must follow the bottom of the characters and must be as wide as the license plate. If required, move the end points to correct the line placement.
    IMPORTANT: Speed estimation accuracy depends on precise positioning of the end points.
  6. Enter the Speed of the vehicle as detected by your radar device.
  7. The Width of the plate is entered for you based on the LPR context that you have configured. If necessary, modify the plate width.
  8. Click Save.

    The camera captures 20 license plate reads:

    The system must analyze plate reads from 20 passing vehicles. The vehicles can be traveling at any speed and you do not need to know the speed of these vehicles. There is no user action required for this step, however, you can improve speed estimation accuracy by editing the plate reads using the following steps:

    NOTE: It might take more than 20 vehicle passes to complete the calibration.

  1. From the main speed estimation screen, click Edit.
  2. Click Advanced on the right side of the screen.
    The license plates from passing vehicles are displayed.

  3. If you notice an incorrect plate read, for example, if a sticker on the back of a vehicle was mistaken for a license plate, delete the image.
  4. You can click on an image to display two images of the license plate. You can inspect the position of the end points of the orange line. If the position is inaccurate, you can either move the end points to correct the line placement or delete the image.
  5. Click Back to return to the main speed estimation screen.
    When the system has successfully read 20 license plates, and when you have entered the speed of at least one license plate, the State displayed on the main calibration screen is Ready.

Results

When the speed estimation calibration is complete, vehicle speed is displayed in the Live Feed page of the portal. It is also possible to configure the vehicle speed to be included as an annotation field in Security Center.