Documentation · plate recognition

Setting up plate recognition properly.

Most plate-reading disappointment is a lens, an angle or an infrared problem, not a software one. This is what to buy, where to point it, and how to configure the log, the alerts and the integration.

There are PDF versions too: LPR best practices and storing and searching plates.

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What an LPR system actually needs

Four things, and the software is only one of them.

  • The softwareVISEC reads plates from the camera stream, logs them, and can act on a reading. It is included in every license, including the free one camera license.
  • The right camera1080p or better. The plate is what matters, not a nice picture of the whole car — frame for the plate and let everything else be a bonus.
  • The right lensVarifocal, megapixel-rated, IR-corrected (day/night), with a DC-Iris or P-Iris. A longer focal length for a more distant lane. The lens is the component people under-spend on and then blame the software.
  • The right infraredMost plate-reading setups use 850nm illumination. Plates are retro-reflective, so mount the illuminator as close to the lens as you can — that is what sends the light back into the lens instead of past it. Choose the illuminator for the distance and the spread you need.
Getting the shot right

Placement beats processing.

  • Aim at the plate, not the sceneA camera set up to photograph the whole vehicle usually gives the plate too few pixels. Fill as much of the frame with the plate as the lane allows.
  • Keep the angle downThe flatter the camera is to the plate, the more of the characters it sees. A steep downward or sideways angle is the most common reason a good camera reads badly.
  • Night is often easier than dayBecause plates reflect infrared, a properly lit plate at night frequently reads more cleanly than one shot into low afternoon sun.
  • Speed is rarely the problemVISEC reads plates at over 100 kph (60 mph), so gate and entrance speeds are well within range. Plates from more than 80% of the world's countries are supported.
Configuring it

Per camera, in the properties.

  • Set the region and the eventsRight-click the camera (or View › Video Devices › Properties › LPR) and open Configure Regions & Events. Mark the part of the picture to read — a tighter region is both faster and more accurate.
  • Turn the log onIn the events and actions box press Add and choose write log for selected camera. Without this, plates are read but nothing is kept.
  • Choose what gets savedThe LPR settings control whether data is logged, whether plate images and full frame images are saved, and in which file formats.
Finding a plate again

The part that earns its keep.

  • Search the logView › License plate log lists the readings, and you search it by plate instead of scrubbing through hours of video.
  • Jump to the momentDouble-click a plate in the log and the video plays from the reading. This is what turns a dispute into a thirty-second lookup.
Acting on a reading

Known plates, and the ones you did not expect.

  • A local database of platesUnder the LPR properties, manage local license plate database keeps the plates you know, with fields for name, address, phone, email and status alongside each one.
  • Alerts and gatesAn action on a reading can show an alert window, send an email, or drive a camera output to open a gate or a barrier — through the inputs and outputs already built into ONVIF and Axis cameras. See access control.
  • Flagging the unrecognisedA vehicle where no plate could be read can raise its own alert, which at a controlled gate is usually the thing you most want to know about.
Sending readings somewhere else

Two ways, both plain.

  • A text fileThe simplest integration: VISEC writes every reading to a text file in a folder, and your own script or software reads it. No API to learn.
  • An HTTP POSTFor a live feed into another system, VISEC can POST each reading as it happens, over the LAN or the internet. The post carries the plate, the image and the fields you have defined, and VISEC can authenticate to the receiving system if it needs to.
  • The fields it can sendAlongside the reading, the stored contact fields are sent as MISC_NAME, MISC_ADDR, MISC_PHONE, MISC_EMAIL, MISC_EMAIL1, MISC_EMAILSMS and MISC_STATUS. Your own fields are prefixed FLD_. Set it up under the LPR events and actions with data dump or HTTP notification.
  • Using VISEC as the LPR engine onlyThis is how sites run VISEC behind an existing VMS: VISEC does the plate reading and posts the results into the other system, which keeps doing everything else.
Questions

Quick answers.

Do I need a special LPR camera?

No. A normal ONVIF IP camera works when it is aimed at the lane properly and has a suitable lens. Placement, lens and infrared matter far more than buying a camera badged for plate reading.

What lens should I use?

Varifocal, megapixel-rated, IR-corrected for day and night, with a DC-Iris or P-Iris. Pick the focal length for the distance to the lane. A fixed, non-corrected lens is the usual cause of soft plates at night.

Why mount the infrared next to the lens?

Number plates are retro-reflective: they send light back towards where it came from. An illuminator beside the lens gets that reflection; one mounted away from the lens sends it somewhere else.

How fast can a vehicle be moving?

Over 100 kph (60 mph). Gate, car park and forecourt speeds are comfortably inside that.

Will it read plates from my country?

Plates from more than 80% of the world's countries are supported. If yours is unusual, test it on the free one camera license before buying anything.

Can it open a gate for plates I approve?

Yes, where the camera has digital output terminals. Keep the approved plates in the local database and set an action on a match.

Can another system receive the readings?

Yes — either a text file it reads, or an HTTP POST per reading carrying the plate, the image and your own fields. VISEC can run purely as the LPR engine for a VMS you already have.

Is plate recognition extra?

No. It is included in every license, including the free one camera license, with no per-plate fee.

Test it on your own lane first.

Plate recognition is included in the free one camera license, so you can prove the camera and the angle before spending anything.

Still stuck on something? Ask us and we will walk you through it

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