Subscriber Discussion

LPR (License Plate Recognition) Minimum Requirements?

I have a prospect looking for an LPR camera. There are speed bumps slowing the car down, but no external lighting. The camera will be fairly level with the license plates at about 20' away. 

The plates are reflective in this state, FYI. Also, I have to stick with Panasonic i-Pro in this situation. Will this camera with HLC work fine? :

https://www.security.us.panasonic.com/docs/wv-s2531ltn_specsheet.pdf

 

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From a PPF standpoint, that camera should be sufficient, unless you are trying to capture 3 lanes wide, but using the Camera Calculator, for a single lane at 20' you will get ~180 PPF:

The primary question is what LPR system are you going to be using? This will have the most impact on the top speed vehicles can be traveling for plate recognition. Even with speedbumps, depending on the size and depth, I have seen vehicles travel 30mph over speedbumps on university campuses, which could cause problems with some LPR systems.

We tested that camera (Panasonic Extreme H.265 Cameras Tested), overall it performed similar to comparable Axis and Hikvision cameras, however, we noted blurring caused by Panasonic's digital noise reduction, which could cause problems with night-time LPR reads. WDR and low light image quality were good. Also, while H265 support is increasing from a VMS standpoint, it could be an issue for 3rd-party LPR systems, so you should be careful about that.

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Panasonic's LPR product through Video Insight: https://www.security.us.panasonic.com/applications/license-plate-recognition/

Cars should be traveling around 10 mph. Perhaps the digital noise reduction can be minimized or shut off completely?

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Automatic DNR can be reduced with the understanding that it could be a much more noisy image.  From the IPVM report:

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I wonder if IPVM could test this camera, with an oncoming car in total darkness except headlights.  I believe that’s what is proposed. 

Daytime should be great, I think total darkness with headlights will be an issue.  Prove me wrong ;)

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I have not used this camera or that LPR product, but my application is very similar, and I get recognition at 30-40mph and around 100ft. with the Axis Q17 series.

I would think setup would be similar on most cameras, so I'll offer a bit of my experience.

I have to use two different presets for day and night. Day is pretty straightforward, just make sure you have the correct PPF, and that the analytic is seeing the plates. Turn off auto-focus and set the day preset.

Night is a little more tricky, but once I have it set, I rarely have to touch them again. Obviously, your PPF and IR illumination need to be sufficient, but you also need to manually set exposure time and max gain. Those two settings are what will allow you to compensate for noise and blur, especially at night. Once you are satisfied the analytic is hitting correctly, turn off everything that is "auto" and set the night preset.

Then I configure a day and night trigger, so that when IR cut occurs, the camera resorts to the appropriate preset. Works great in this city environment.

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