Poor IR contrast in new Tennessee license plates

Flintstone61

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I wonder what the Aliens from Zetareticula use to find cows in the middle of the night. And what kind of laser do they use to cut out thier organs. Maybe Neutrino IR.
I bet they have some info on what works.
Somebody greased the political wheels to make " better cheaper faster" plates, All in a guise to continue running Moonshine, Hookers and Blow thru Tennessee unmitigated.
Thankfully im not a Conspiracy theorist. I just play one in the forums.
 

ARAMP1

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I wish I had a TN plate I could test with for my Axton IR unit. I only have a handful of them come through the neighborhood from time to time but I don't have any record of one at night.
PM me your address and I'll send you an old one.
 

wittaj

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PM me your address and I'll send you an old one.
The new plates only came out in January 2022, so by an old one I am assuming it is the newer 3M printed plate that you have received since January 2022 and have already replaced it or got rid of a vehicle?
 

ARAMP1

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The new plates only came out in January 2022, so by an old one I am assuming it is the newer 3M printed plate that you have received since January 2022 and have already replaced it or got rid of a vehicle?
Yeah, this whole new plate thing has been a debacle. Plate for my vehicle is due in January. I replaced it with a new, blue one in Jan of 2022...well, I paid for it on 6 Jan, 2022 but the new plate didn't arrive until mid Feb. I renewed it for Jan of this year and instead of sending me a new sticker, they sent a whole new plate. On a facebook community forum, someone described how they ordered a box of cigars and received a full up box of 200 new, unissued TN license plates. People are describing hours of wait times at the county clerks office. (some instances where you can't renew online). All this going on while the elected county clerk took a two week vacation. "Shitshow" would be a good description of this license plate rollout. But hey, look at the bright side, we don't have an airplane flying backwards on our plates like Ohio does.

But anyway, I have the new blue plate from 2022 that they replaced for me in 2023 that I can send him.
 
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It's good to see that manufacturers are responding to the 3M-style printed plates that lack contrast under 850nm light. This is the way of the future, with LPR cameras switching to 730nm IR or visible light. I have become convinced that the growing number of states that are using the 3M plates don't give two flips how visible they are to LPR cameras. They just want the revenue from being able to print hundreds of different vanity plates.

I checked with @EMPIRETECANDY, and he confirmed this camera model is available for $490, but requires a special order with extra waiting time. The main drawback is that it lacks the full varifocal range of the Z12E cameras. I'm hoping that Dahua will address that in a future model revision. I'd particularly love a cheaper model that doesn't include the onboard ALPR software.

Amcrest has a visible light LPR camera available at Amcrest 4MP UltraHD License Plate Reader ANPR AI IP Camera Bullet IP4M-1062EW-AI. This is a copy of another Dahua model, but again demonstrates the trend away from 850nm illumination for nighttime LPR.
 

biggen

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I'm curious how visible this is. I would think it would be much more noticeable than 850nm.
 

Starglow

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Years ago NC changed from blue & white plates to red & white, but apparently the police scanners had trouble reading them so now we're back to the old blue & white. They also passed a law requiring new plates every seven years but that has been suspended due to aluminum shortages and some older NC plates are so worn and faded you can't hardly read them anymore.
 
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So why do you expect that 730nm will solve this issue? This is just beyond Inferred. How will this be any better than 850nm?
The printed plates have much better contrast under 730 nm light as opposed to 850 nm light. It's all a function of the reflectivity of the materials.

This video shows the difference:


So the future is either 730 or 740 nm illumination, or visible light. 850 nm illumination is a dead end, because these 3M printed license plates are becoming more and more widespread.
 
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I'm curious how visible this is. I would think it would be much more noticeable than 850nm.
It is unfortunately quite visible, although not extremely bright. So they would be quite noticeable in a residential installation, but not blinding by any means.

I am taking a much different approach with my illuminator design. I'm using a soft white LED, which blends in very nicely with the porch lights people use around their homes. I will be showing some results very soon.
 

erkme73

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It sounds like it's more than just changing the IRs - but actually the sensitivity of the imaging sensor in the camera, correct? IOW, simply replacing (or adding to) the old illuminators with 740nm LEDs won't fix the issue?
 

erkme73

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I am taking a much different approach with my illuminator design. I'm using a soft white LED, which blends in very nicely with the porch lights people use around their homes. I will be showing some results very soon.

Would that then require the cameras to be set to day mode (no IR) for that to work? What about those of us without any ambient lighting, where drivers aren't expecting any lights at night? In my use-case scenario, I have a completely dark street. Having any lighting (even the 740nm) would be very obvious - with white light being potentially blinding.
 

Parley

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I have been experimenting with the plates here in California. I have added a 60-degree 850nm IR illuminator within a foot of my LPR cameras and it has helped a lot. I am in the process of adding a 2nd IR illuminator and I have a couple of choices. One, which I have on order is around twice as powerful as the current one. I want to test it out to see if it is too powerful and overpowers my LPR cameras. Otherwise, I will go with the style I currently have as the other option, if the other one is too powerful.

One thing about the test they did not do in the above video is that they did not give out the distance to the plates they were testing. The power of the IR beam fades rapidly with distance. Also, dirty plates make a difference.

Where I am at now is that during the day, I get virtually 100% of the plates. At night, I am in the 98% plus range. However, what is happening in my neighborhood is that more and more people are spraying a non-reflective coating on their plates. This is due to two intersections close by that now have 4-way license plate cameras installed. The price of the tickets is $600. This has been all over our Next Door site.
 
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It sounds like it's more than just changing the IRs - but actually the sensitivity of the imaging sensor in the camera, correct? IOW, simply replacing (or adding to) the old illuminators with 740nm LEDs won't fix the issue?
You are correct. It is not just a matter of changing the illuminators. It is a matter of changing the optics so that the different wavelength will focus correctly on the sensor.

I learned this in my own experiments. Even with a very strong 740 nm illuminator, my cameras did not work in nighttime mode. This was also confirmed by Andy in his conversations with the Dahua engineers.

The solution is to keep the camera in daytime mode at all times, and use visible light illumination at night.
 
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Would that then require the cameras to be set to day mode (no IR) for that to work? What about those of us without any ambient lighting, where drivers aren't expecting any lights at night? In my use-case scenario, I have a completely dark street. Having any lighting (even the 740nm) would be very obvious - with white light being potentially blinding.
That is correct, you leave your camera in daytime mode. However, I am constructing my illuminators with a reduced duty cycle. Furthermore, I’m using a warm, white LED color. To a person driving by, the light will look like a porch light.
 
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Where I am at now is that during the day, I get virtually 100% of the plates. At night, I am in the 98% plus range. However, what is happening in my neighborhood is that more and more people are spraying a non-reflective coating on their plates. This is due to two intersections close by that now have 4-way license plate cameras installed. The price of the tickets is $600. This has been all over our Next Door site.
Reflective coatings won’t help one bit against an LPR camera with white light illumination. If it is visible in the daytime, then the LPR camera will read it.
 
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