License Plate Capture Shootout 2014

Geutebruck USA • IPVMU Certified

The right tool for the right job. Don't try and shoe horn cameras not specifically designed for tag capture into that role, unless you have reliable light controlled scenes.

Alon Hasson

I was hoping to see various LPR cameras versus each other (i.e. Bosch vs Messoa vs Geovision) ... not LPR vs a dome.

Luis Carmona

Geutebruck USA • IPVMU Certified

In reply to Alon Hasson

I think that's a good test for IPVM to do, but this was an important one as well as it's been looooong overdue showing people, particularly end users and integrators who swallow too much of the manufacturer sales pitch about how great regular megapixel cameras are at capturing tag shots.

Ethan Ace

In reply to Luis Carmona

That's essentially it right there. Doing a shootout of capture cameras or LPR software isn't out of the question. We felt that this fundamental test was a better place to start.

Undisclosed #1

Interesting test, but none of these images would work with any LPR software I've tried day or night. To do LPR correctly, you need to do three things;

1. you need to get a much tighter shot of the plate, about the width of a car and not much more, hence the reason the Geovision has such a long lens. We run our 5-50mm lens on our LPR camera at 50mm at about 60-70'. This will solve some of the issue you are having with head or tail lights and give the plate the resolution it needs for LPR. Expecting the camera to adjust properly when the plate is so small relative to the entire scene is a problem. If you need more than VGA resolution it's because you are expecting the camera to capture too much of the scene.

2. The other issue you have is the relative angle of the lens to the plate. The car has to either be further away while still maintaining the tight shot or the camera has to be closer to the road. This will address the motion blur issue as the car will have less lateral motion relative to the camera.

3. The last issue is you need a good illuminator, one that can overcome the backlighting caused by the headlights. LED's built into a camera are never going to cut it as they are designed to light a wide area to match the focal length of the camera. You need a good narrow beam illuminator capable of lighting say 4x the length you want.

Ethan Ace

As we mention in the report, the point of this test was to show the tradeoffs between these three types of cameras, and to overcome a lot of the manufacturer marketing you hear about what's needed to capture plates. Reality is, people ask to simply capture far more than they ask to recognize. As you mention, real LPR systems are specialized and require different setups. It's not out of the question that we test them in the future, but that was not the scope of this test.

One note, the angle to the plate in this case was fairly shallow, only about 15 degrees, which is well within the ranges of recommendations I've seen from LPR providers. It may look like more in the images, but it was kept shallow. Cameras were right on the shoulder of the road, and aimed fairly far.

Undisclosed #1

In reply to Ethan Ace

You mean like when one German camera company claimed that with their camera you can clearly read license plates across 4 lanes in a gas station?

Jon Dillabaugh

Pro Focus LLC

That works well if you have a high MP camera and plenty of light.

Undisclosed #1

In reply to Jon Dillabaugh

And live in Europe with their giant plates.

Ethan Ace

I just measured, out of curiosity. American plates have a character size of about 2.75" tall by 1.25" wide. The EU plate has a character size of about 3" x 2", a little wider in some cases. They seem to be more of a variable width font that North American plates, where we fix the character width.

So for anyone wondering, there's the character size difference.

Undisclosed #1

In reply to Ethan Ace

Good to know. But besides the character size, they seem to be thicker/chunkier fonts however one would describe it. The main problem I have in the U.S. is license plate frames that obscure part of the characters, for example, a 7 & Z or Q & O may look the same if the bottom part of the character is cut off from view. Not sure if euro countries are more strick on this or have more white space above/below the characters to compensate for this.

Luis Carmona

Geutebruck USA • IPVMU Certified

Even if your missing some characters, I'd imagine you should still be able to look up a plate based on the readable characters position and narrow it down by the statisctical probability of the same make and model car having a plate with, for example, a Honda Civic having the first character of G and the last two characters of 1 and 7. Of course what I assume to be obvious is not always so. It'd be nice to hear from some law enforecement on how easy or difficult it is to track down the correct vehicle in an incident based on partially readable characters of a plate in a picture.

Jon Dillabaugh

Pro Focus LLC

These findings match what we have have found in our own tests. We ended up using a Dahua 3MP dome, but we don't use the integrated IR. Our customer has placed enough lighting in the target area so that IR wasn't needed. However, if you don't have the ability to add traditional lighting (we found we needed at least 20 lux on target), then you will need to add some IR floods. We used a Raytek white LED lamp in our testing, but would probably recommend using IR instead, so that you don't blind the drivers.

Undisclosed #1

Interesting that you mention white lights as our local toll roads are switching to LPR and they use flashes like still cameras. So annoying, everytime you drive through it flashes in your eyes, especially if you are a camera geek and look up to see what type of cameras they are using, LOL.

Simone de Titta

I'll definitely cut&paste this link to anyone who (almost weekly..) always asks to me "but, is your LPR analytic able to read plates with moving cars and by night??...."... And my answer is always "It does not depend on my LPR analytic!.. It' depends 95% on the camera, that must be a camera for LPR. Give to me a good image and I will read it.. That's it!"...:)

By the way, I am surprised about the decision to test a low light camera and not instead a good WDR camera.. I mean, of course I well expect that a "lightfinder" camera is working bad for this issue: those cameras work on very sensitive open iris, so when the headlight of car is coming of course all becomes "white".. Different thing is to use an IR, that it's a different frequency, not a different quantity of light..

I would be more curious to test instead those WDR cameras such as the Axis Q1604 for example. I had already tested myself infact the Q1602, lightfinder, and of course it's definitely not the correct one for this purpouse.

Anyway, I fully agree with Luis' sentence: "the right tool for the right job". Always!!

Price, price, price........I am sorry, to go by bicycle to Brasil is surely cheaper but probably not always reliable...;))

Cheers,

Simone

(TechnoAware)

Undisclosed #1

In reply to Simone de Titta

We are using an Axis lightfinder camera, the Q1604 and it works amazingly well day or night for LPR use. When at the last ISC West (actually coming up again in 3 weeks), I asked everyone that sold LPR software what camera they would recomend to complement their product and they all said the same thing, the Q1604 (not to be confused with the Q1604-E which would not be good for this).

Brian Selltiz

•Mar 16, 2014

IPVMU Certified

In reply to Brian Selltiz

Can you explain why the E version of the Q1604 would not work and the indoor model would?

Undisclosed #1

•Mar 17, 2014

Because the housing for the "E" version is too small to accomondate a large lens and the lens it comes with is too wide a focal length to be useful for this purpose. I think it only goes to 8mm. I put in a Fujinon 5-50mm to get a nice tight shot. Wether for LPR or LPC, to get good clarity, I would not go wider than about 8' wide at the point of plate capture. It's best to use a seperate camera to cover the entire scene. What was tested above is great, actually helped me personally, but to get a good plate capture at 1/500/sec, the overall image is too dark any way to serve a purpose as an overview camera.

Lee Zanter

•Apr 04, 2014

IPVMU Certified

Do you put it in a different enclosure then? Why not use the Lens that Axis recommends? Like Theia which is 9-40mm. The only reason im asking you is that im going to propose Axis 1604-E with the theia lens. Im fairly new to LPC. I have to go with Axis because i need to use exacq edge setup.

Undisclosed #1

•Apr 04, 2014

In reply to Lee Zanter

The problem with the "E" model is the enclosure is too small to put in a larger lens so it makes more sense to go with the regular version and buy the Axis enclosure seperately, about the same price. Why would Axis recomend a Theia lens when they sell an Axis branded 15-50mm lens? Add a good illuminator and you can go full LPR instead of LPC. This year, at ISC, I've seen more LPR vendors than in year's past.

Lee Zanter

•Apr 05, 2014

IPVMU Certified

In reply to Simone de Titta

Im sorry but im confused. Are you using different brand enclosure then Axis? OR are you using T92A vs T92E? As far as there lens they have recommendation under accessories tab Here "Are these lens not suited for the job"?

All i'm wanting is to be able to read plates day or night. No analyics

illuminator was going to be raytec

Undisclosed #1

•Apr 05, 2014

In reply to Lee Zanter

We use the Axis T92A enclosure but you can use any enclosure, Pelco makes nice ones for a much lower price. I'm just not using the enclosure that comes with the q1604-e because it's too small to hold 3rd party lenses, so better to say a few hundred and get the Q1604, use the money you save to buy the T92A enclosure. As far as the lens, you can use any lens you feel comfortable with. Being a pro-photographer, I have a preference towards Fujinon but you need an adapter to make it work. The Axis lens probably works without an adapater. Never heard of the brand lens you mentioned. Raytec makes some nice new illuminators and the Axis is actually made by Raytec. You'll be able to view plates just fine and one day you'll appreciate the ability to capture the plate numbers so you can search to see how many times a suspicious car has been by the property or trigger an alert if a certain plate number was read.

Brian Selltiz

•Mar 16, 2014

IPVMU Certified

+1 for testing the Q1604

Jason Vidéo

M15 from Mobotix with an LPF

Subhash Challa

We have gained a lot of experiance in LPR solutions over the last 3-4 years and one of the key factors that determine the quality of image is the 'reflectivity of plates'. All these tests seems to be on vehicles that have very good reflectivity properties for the license plates. However, over time reflectivety of these plates degrade and have varying quality of images for a given camera settings - especially in the night. In Asian countries where traffic is composed of a mixture of reflective, non-reflective and partially reflective license plates none of these cameras provide consistent high quality images. They are usually good for some vehicles and not so good for other vehicles. We ended up working with a manufacturer to provide a combination of cameras to help with the getting usable images for dealing with varying reflectively for both day and night.

Undisclosed #1

In reply to Subhash Challa

I agree, there are plates in the US that may be 50+ years old and clearly one can't expect the reflectivity to still exist even it it existed when new. Our city replaces traffic signs every 8-10 years because they no longer meet reflectivity standards but car owners are never encouraged to change their plates. Even a coat of dust on a plate can cut it's reflectivity down dramatically.

Ethan Ace

Car owners are never encouraged to change plates? Here in PA, we changed all of them in the mid-2000s. NY just went through a change from the old white plates to black/orange. NJ changed theirs in the past decade, as well.

For what it's worth, the Volvo in this test is mine. It has not been washed all Winter, I've been driving on brined roads during the snowy months we've had, and that rear plate is about four years old.

Undisclosed #1

In reply to Ethan Ace

Not the case on the left coast. Here the plate goes with the car for life. Actually, the plates are ordered when you buy a new car and come within 6-8 weeks, so you drive without any plates, not even a temporary plate until you get yours. So if you have a 1954 Oldsmobile, you have plates that where made in 1954 and are 60 years old. If you have vanity plates, they stick with you for life from car to car. You can have a brand new car and put 1954 plates on it. There are Ford Model T's at car shows with plates 100 years old (BTW, 1914 was the first year for license plates here, not sure they were reflective then).

The interesting trend is many states are printing flat license plates. California still has raised letters & numbers. I'm waiting for the first state to have barcode or QR code plates.

Subhash Challa

Here are some images from our experiments to demonstrate the impact of the nature of the license plates.

Reflective & Non Reflective Challenges

Undisclosed #1

In reply to Subhash Challa

I know it sounds wrong, but our experimentation showed that at night, the best way to see a reflective plate is to throw a lot of light on it. Sounds counter-intuitive, but works. Imagine this, when do do get the the absolute best license image? The middle of the day, with the power of the sun to illuminate yet that is not too bright and doesn't blind the plate number. So what you need to do is recreate that as best you can. We use a RayTec RM100-30 and honestly, wish we had gone with the RM200-30 but we get very clear plates, day or night, reflective or not. I'm hoping we can swap out the RM100 with the RM200 on the next phase and use the RM100 where we have closer proximity to the plate.

Subhash Challa

Increasing illumination will work until you start washing out the plate eventually. The amount of illumination that will lead to this is not straight forward to calculate. Another variant is if you position the illumination on axis or off-axis. On axis like what most integrated IR cameras do and off-axis is where you provide additional IR illumination with some off-set to the camera. This will help get better balance but it will increase cost and complexity to some extent.

Undisclosed #1

In reply to Subhash Challa

It's almost hard to get too much illumination and on axis or off does not matter as the camera will adjust the iris, shutter speed and gain to compensate. Here in California, some cities have red light cameras to catch if you run the traffic light. They use white lights about 1' in diameter and use two of them shined on the subject if I run the red light to make a pretty picture of the person driving, the plate number and color of car, all on axis as they put one each on either side of the camera. It is blinding.

Any built in illuminators will be too weak because these are PoE cameras. Don't know if you ever used a managed switch, but usually they tell you the power usage. When you have IR cameras pulling 3-4W during the day, and go to 5-6W at night, that means effectively, you have 2W or LED lighting and don't think that can possibly overcome head or tail lights. So what happens is the camera sets the shutter speed as slow as you let it, cranks up gain, opens the iris and you will get noise, motion blur and the exposure will be balanced to the point of making the plate look white.

Subhash Challa

One can get too much illumination - at least that is our experiance. We ran into this problem when we are dealing with LPR in APAC region where we have a mixture of non-reflective and reflective license plates. Settings that make non-relfective work at high speeds at night will almost surely wash out the plates that are reflective and settings that make it work for reflective plates will lead to poor contrast and low visibility for non-reflective. We have overcome this by using a dedicated 'non-reflective' friendly camera and illumination and dedicated 'reflective' friendly camera and illumination - and we need to have a sophisticated ANPR engine to deal with this (which we have built) to meet the user acceptance criteria in several of our installations.

John Honovich

IPVM

"Any built in illuminators will be too weak because these are PoE cameras."

Your claim is contradicted by our test results above.

Undisclosed #1

John, with all due respect, yes, I did contradict the results and here's why. When cars are moving at even neighborhood speeds, say 25mph, most cameras can't adjust exposure or leverage WDR fast enough to go from a dark night time scene to one with 2 glaring headlights that comes and go within a few frames.

When you take a still shot on a stationary car as in that test, the camera has time to correct the exposure and if the camera has good WDR capabilities, yes, you can read a plate with weak lighting. I know because I read plates at night with ordinary cameras on cars that have to come to a complete stop at a gate.

To be able to achieve this on a moving vehicle it's different. The additional lighting is to light the scene so the camera does not have as far to adjust and can overcome the rapid change in lighting.

It is possible to use built in IR illuminators in theory, but the car would have to be very close to the camera and any general purpose camera with built in IR illuminators is not likely going to have as narrow a field of view as would be required for LPR, at least my definition which is the optical character recognition of a license plate.

John Honovich

IPVM

"When you take a still shot on a stationary car as in that test"

Yet again, your are making claims that are obviously false and easily resolvable by even a casual review of our report. We tested at 40+ mph. We even included a series of videos that showed this above.

If you don't read the report, don't comment. Ok?

Undisclosed #1

I was referring to the "report on headlights" that you refered to in your comment, I do not see anywhere in that test where it was done at 40 mph or any of the vehicles were in motion and if the images were crops or full sized images. Maybe you can clear that up.

Yes, I do see that you did the tests at 40 mph when I read it the first time and I'm not convinced one single nighttime image above in this article can be read by any LPR software and provide any level of success. I am at your service if there's any help I can provide to prove this out with any LPR software.

John Honovich

IPVM

This report was done with headlights as well, as the videos above show, and the integrated IR cameras were able to capture license plates with headlights. Either way, your statement misrepresents and is contradicted by this test.

Secondly, this is not an LPR report. That's why we titled it explicitly 'License Plate Capture Shootout'. There's a difference between LPC and LPR.

In my experience, many of these images will work with LPR software but I'll leave this whole topic to a future specific LPR test. The goal of this test was LPC, as stated in the title, and was chosen because it reflects a far more common use case (LPC vs LPR).

Undisclosed #1

Thanks John, this has been a great help. I took at look at cameras we have for this purpose, installed way before the LPR stuff. My problem is brake lights blow the image away. I set the image to meter much darker, actually so dark it was worthless for anything other than counting taillights and viewing plates. Where the plates were totally unviewable before, they are now very dark, but you can make out plate numbers.

Never would have though about doing that if not for this article. Thanks.

John Honovich

IPVM

Our report on headlights shows a similar benefit of adding illumination. In particular, it helps to counterbalance the light that the car is producing itself.

Deegan Pope

•Mar 17, 2014

I think most of us are not trying to do LPR at less than 1lux at 40mph+. That seems nearly pointless. It's the parking lot exits at 10-20mph and 3-20 lux that seems to be more common.

John Honovich

•Mar 17, 2014

IPVM

Degan, both tests were performed in this report - fast and dark, and slow and 'relatively' bright. Even in parking lots, were you have 3+ lux, the problem is not that it's too dark, it's the light emanating from the vehicle itself that causes issues unless additional illumination is added (IR or white).

Jon Dillabaugh

•Mar 18, 2014

Pro Focus LLC

Deegan,

My experience is that my customers expect clear images from cars driving up to 45MPH without adding much visible lighting. We can throw some IR LED, either integrated or external floods, but the one project we have been working on doesn't want to blind the drivers with visible light. And for good reason. You need a direct light source that can overcome the strength of both headlights and taillights. You will need additional overview cams as well if any info other than plates is important.

Undisclosed

•Mar 24, 2014

We are interested in installing this at the front gate of our home. The camera will be facing north, and will be mounted on a monument approx. 7' up. Our main goal is license plate reading at day and night (car will have to pull up to the gate and stop).

Should we stick with the 2.0W, or would going up to the 3MP or 5MP be a better option?

Thank you for the articles!

John Honovich

•Mar 24, 2014

IPVM

In reply to Undisclosed

Greg, it depends on the width of the FoV / number of lanes you want to cover. Presuming it's 2 lanes, I think 2.0MP will be fine. Also, in general, for night time viewing, I am skeptical of the additional benefit of higher pixel counts even with IR on.

Undisclosed

•Mar 25, 2014

In reply to Marcin Kucharski

Thanks John. It will just be our front gate, which is about two lanes wide (it's wide :).

Since we'll use it for daytime also to see who is at the front gates, should we go with higher MP? Would going with 5MP and the lower FPS mess up the nighttime license plate capture?

Marcin Kucharski

•Apr 01, 2014

Have you applied some IR illuminator for SNB-5004 tests? If not then it's a little ridiculous comparison.

John Honovich

•Apr 01, 2014

IPVM

It's not a 'ridiculous' comparison because LOTS of people like or want to use professional cameras with no IR illumination. For all of those people, this is an important comparison to show them the limitations of such an approach.

Marcin Kucharski

•Apr 01, 2014

That is why the more it should tested with additional IR illuminator for such types of cameras...

Deegan Pope

I had a challenging LPC job in the DC area where the closest place we could put the camera without going 35 degrees off axis was 185ft away. We used a samsung SNB-7002 and a tamron M13VG850IR 50mm megapixel daynight lens.

Even with the lack of lighting and 17ft FOV (full zoom on the 50mm) we're pulling plates at night in both lanes as well as the car colour, make and model. I may add an iluminar for good measure, in case we've just always had moon light, but i'm very impressed with the outcome.

Luis Carmona

Geutebruck USA • IPVMU Certified

Deegan, that's pretty good. What speed are the cars usually going at?

Deegan Pope

In reply to Luis Carmona

Coming towards the came probably 20-40km/h and going away from it likely 40-60km/h. I found that if there was cloud cover and no moon we had a harder time making out the plates. So it might be time to add an IR or some white light.

We just in the last hour here finished putting up a Hikvision 3MP cam in the back alley of our building here and we'll see what it can do at night. We do a lot of low light testing and i'll try and put up some of the shoot outs here.

Luis Carmona

Geutebruck USA • IPVMU Certified

Brilliant!

John Honovich

IPVM

Deegan, thanks for sharing!

"I found that if there was cloud cover and no moon we had a harder time making out the plates."

From the look of the road, it seems fairly well lit from ambient / street lighting. I think that is what is making the difference there between a dark/darker roadway.

Deegan Pope

•Apr 11, 2014

I don't think it's very well lit. It is a large area and there is only one dim light. This samsung cameras can really make things look brighter than they really are.

John Honovich

•Apr 11, 2014

IPVM

In reply to Juan Castaneda

It's worth measuring with a lux meter because there is a big difference in low light performance between under 1 lux (dark road) and 3 to 5 lux (street lights nearby). This is for all cameras. Oh and the Samsung cameras we tested are newer and better in low light than the 7002 you used (compare 7002 specs vs 5004 specs).

Juan Castaneda

•Jan 14, 2015

John,

Do you remeber the frame rate on this tests? Do you think lowering the FPS could have a negative impact on capturing the plate at a greater speed?

I am using a low light camera with WDR (120 dB), 3D Noise filtering and Add on IR to do this. Do you think the better WDR spec could give me some balance with the fact that the IR is not "Smart IR"?

Reactions:

John Honovich

•Jan 16, 2015

IPVM

Juan, what is the speed of the vehicles you are planning to monitor? what frame rate do you plan to use?

For example, a car going 30mph travels 44 feet in a second, so if you only do 1fps, the chances you miss the plate are very high.

As a rough rule of thumb, I'd make sure you had a frame every 3 feet or more. In the case above (30mph / 44 feet per second), that would mean 15fps. Of course, you still need to have a short shutter speed to eliminate blur.

If you are using external IR, as long as the range is sufficient that should be fine. In our testing, WDR does not make a big difference in LPC performance.

Reactions:

Juan Castaneda

•Jan 16, 2015