Poor IR contrast in new Tennessee license plates

looney2ns

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Seems like a pretty big blunder on some of these states to not think about this.
That's what governments do best....screw up.

Someone thought it would save the "taxpayer" pennies per plate. So they spent 4 million $$ to study the issue. And another 8 million to retool the plate making machines'. Police depts will have to ask for another 10 million to replace the LPR cams.

You can see the savings, right?
 

wittaj

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That's what governments do best....screw up.

Someone thought it would save the "taxpayer" pennies per plate. So they spent 4 million $$ to study the issue. And another 8 million to retool the plate making machines'. Police depts will have to ask for another 10 million to replace the LPR cams.

You can see the savings, right?
And let's not forget to add this million dollar plus mistake LOL:

 
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My progress so far: I've ordered an inexpensive 850nm illuminator, and I have some unmounted cameras to use in my tests. I've also contacted the plate manufacturer to see if I can get some sort of test tag using the same colors and materials as a standard tag. If I can do that, I'll be able to experiment with different camera settings and different levels of IR illumination to see if I can improve the contrast between the lettering and the background. I'll also check to see if different camera models from different vendors make any difference.

It is difficult to find inexpensive 740nm illuminators. This isn't surprising, as they are more visible to the human eye, and hence less useful for general security purposes (outside of LPR). There are some cheap ones available from China on eBay, so I may gamble and order one of those if I can't find something from a domestic vendor.

It is possible that some local agencies may not be aware that their LPR systems are going "night blind", because the new tags have only begun to roll out. Modern LPR systems do allow you to check for vehicles with unreadable tags, but unless someone does so, it may be a while before they realize what's going on.
 
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So as it turns out, 740nm illuminators (which are one of the standards for municipal LPR cameras) are extremely difficult to locate. But as I learned after communicating with one of the engineers at Axton, 730nm LED light sources are a completely different matter.

730nm LED "grow bulbs" for indoor horticulture are quite common. (Let's hear it for the cannabis industry. :)) I ordered a couple of 7 watt 730nm bulbs with a PAR30 form factor and an E26 base. I was even able to specify the illumination angle of the LEDs in the order. Once I receive them, I will place them in an outdoor floodlight fixture, point them in the same direction as my cameras, and use a smart outlet or switch to turn them on and off at sunset and sunrise.

It should be interesting to see how my Dahua cameras work with 730nm illumination. I'll update everyone as I get results.
 
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And your neighbor will wonder how they have a growth patch about 20 feet wide going thru the middle of their yard :lmao:
Sacrifices must be made for the greater good. :)

Besides, my neighbors like me a lot. I just gave one of them the license plate of the hit-and-run driver who sideswiped her parked car. And for another I gave the police the license plate of the vehicle driven by the people who broke into their truck by smashing a window.

But there is one thing I'm now curious about: what if these 730nm bulbs enable my cameras to read paper tags at night? From what I've been reading, that is one of the reasons why 740nm illumination is used in dedicated LPR systems. If so, I may wind up keeping the bulbs installed regardless of what happens with the license plates.
 
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wittaj

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Yeah I can't wait to see your results! Do the bulbs give an effective distance range?

It appears DOTs are starting to use 730nm to be able to see the occupants in vehicle too, so maybe in conjunction with an overview cam, we can start to get occupants?

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Yeah I can't wait to see your results! Do the bulbs give an effective distance range?

It appears DOTs are starting to use 730nm to be able to see the occupants in vehicle too, so maybe in conjunction with an overview cam, we can start to get occupants?
No effective distance range, but from what I could see these grow bulbs use the same LED emitters as the IR illuminators do. They are even specified in the same illumination angles (I chose 30 degrees). Given that I'm about 60 feet from the road and will be using a 7 W bulb in each direction, I expect good results. And I can always order bulbs with different illumination angles if needed, or 21 W bulbs if I really want to light up my street.

I hadn't thought about being able to view the occupants, but I'll definitely do some experiments along those lines as well using my PTZ camera. The police would absolutely appreciate that if a carload of door checkers hits my street.
 

wittaj

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Yeah, this will be great because I suspect many states are going to plates that are going to make this harder!

I guess the experiment with trying to adjust the white balance failed with B/W and infrared?
 
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Yeah, this will be great because I suspect many states are going to plates that are going to make this harder!

I guess the experiment with trying to adjust the white balance failed with B/W and infrared?
It had no effect whatsoever. I did wind up increasing the contrast, which seemed to help a bit, but either the DoT will have to replace these plates or 730nm illumination will be required going forward. Of course, that assumes the plates will be viewable even at that IR wavelength, but at least in that respect I'm hopeful.
 

wittaj

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Buy a couple of these bad boys lol


This one says it has a range of 820 feet


 
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Buy a couple of these bad boys lol

This one says it has a range of 820 feet
With that much IR power, I could illuminate my entire street. :oops: For those who are interested in a somewhat smaller scale deployment, Axton quoted me a price of $319 each for their PoE Nano illuminators customized with 730nm LEDs.

But I'm going to see if I can do this a bit more cheaply. $34 for two 730 nm LED bulbs + $30 for the mounting hardware and fixtures + $20 for a smart switch will go over much more easily with the CFO (i.e. my wife).
 

ARAMP1

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Not sure the original source...someone posted it on our community fb page in (just outside of) Memphis.
 
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For those who are interested, here are three sample plates I photographed using a portable 850nm IR camera that I put together. You can see the contrast issues with the new plate and also with a Woman Veteran speciality plate. Only the older license plate has good contrast.

As it turns out, these color plates were manufactured using a 3M process. Unless black lettering is used, everything fades out due to poor contrast. What is interesting is that 3M screwed up the plates in Ontario two years ago, forcing the province to go back to their old design (with a white background).
 

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