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Plate Capture Using Handheld

The Plate Capture Using Handheld functionality utilizes the device camera and License Plate Recognition (LPR) software to quickly identify vehicles in the field. Its primary purpose is to ensure highly accurate plate reads by educating users on proper camera framing, distance, and the use of on-screen guide boxes. This article is intended for OPS-COM administrators and field enforcement personnel using the Android application.

Setup and Configuration

The optical character recognition functionality is built directly into the mobile application and relies primarily on proper physical technique rather than software configuration.

Admin Side: 

  1. Open the OPS-COM parking enforcement app on your handheld device.

  2. Grant any requested operating system permissions to allow the application to access your device's camera.

  3. Tap Search Vehicles from the main menu to access the capture screen.

Using this Feature

Enforcement personnel use the on-screen viewfinder to align the license plate, allowing the image processor to extract the alphanumeric characters.

Framing and Capturing a Plate

  1. Tap the camera icon to open the viewfinder.

  2. Position the device so the license plate is visible within the on-screen bounding boxes.

  3. Keep the device steady until the system successfully captures the plate and returns to the Plate Read screen.

  4. Tap the captured thumbnail image of the plate to open the full context image.

Visual Cues & Status Indicators

The viewfinder provides two outlined boxes to help determine if minor physical adjustments are needed to properly line up a plate:

  • Red Box: Indicates the maximum scanning area. If the physical plate extends outside of this red area, it will not be read by the system.

  • Blue Box: Indicates the optimal target area. It is highly advisable to keep the entire plate inside this blue box to ensure the LPR engine processes it correctly.

Best Practices and Considerations

  • Include the plate edges and background: Do not capture the plate too tightly. It is better to include the entire plate plus some of the vehicle's background. If the physical edges of the plate are excluded from the picture, the LPR engine struggles to distinguish the actual plate number from secondary text (such as province or state names) and may return an incorrect read.

  • Exclude complex vanity logos: Focus the view specifically on the plate numbers. If scanning a vanity plate with heavy graphics, position the camera to exclude the logo from the blue bounding box if it consistently confuses the image processor.

  • Review context images to correct hardware offsets: Tap the thumbnail to view the full context image if your reads are consistently failing. With some device hardware, the plate may look perfectly centered in the live viewfinder, but the actual processed shot comes out off-center. The context image displays a date-stamped, red bounding box representing exactly where the system processed the image, allowing you to manually adjust your physical centering technique.

Step back and try again: Do not be afraid to back away from the vehicle if the scanner is struggling. We often exaggerate the distance and pull back quite a bit to yield better results. The image processor can accurately read plates even when they appear surprisingly small within the viewfinder.

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