Subscriber Discussion

We Need To Catch A License Plate At Dusk

NR
Nick Riedman
Sep 22, 2017
IPVMU Certified

Good morning,

I work in the City of Greenfield IT department. In the central East portion of Indiana and central West portion of Ohio the cemeteries have been getting robbed of urns. These urns can be collectable and often carry large amounts of bronze. Hundreds are missing across several small town cemeteries. We have installed several cameras in attempts to grab a full license plate or clear facial image of the thieves. With no luck so far.

Currently we installed another camera and tested it last night at dusk.The images were not useful at all. We had an issue with auto focus following night bugs and the headlights washing out the image.

The main camera is a Axis Q6045 with the following changes from default (changed as of this morning).

Auto Focus - Off

Wide Dynamic Range - Off

Allow Slow Shutter - Unchecked

Enable Highlight compensation - Checked

Day Night shift priority - Night

Noise reduction - Off

We also have a P3367 at ground level but oblique to the vehicles. I do not see where I can lock the focus on that camera. The daytime picture is quite good but night is terrible. The following settings have been changed from default.

Day/night shift level - Night

What else can we do? This has become a priority for our PD detectives as the majority of our urns are now missing and the only license plate we have ever captured was partial and came back as no vehicle of the type we recorded had a plate within that number range, it was stolen.

We need a clear picture at the difficult time of dawn or dusk when the thieves strike.

Thanks for any suggestions.

Dave

JH
John Honovich
Sep 22, 2017
IPVM

Nick, sorry to hear that.

Do you have any IR illuminators or cameras with integrated IR? We'll pass this to Axis in case they have recommendations but the combination of headlights and dusk are hard to deal without IR.

Related: Top-Used License Plate Capture Cameras which has many Axis recommendations but not the models you used.

NR
Nick Riedman
Sep 22, 2017
IPVMU Certified

We do not have an IR illuminator available, we have one watching a critical point now but no spares. We will see what effect the changes I made have this evening, but I am not hopeful.

A grandpa with a shotgun would, I think, be a good solution.

Thank for the response,

 

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U
Undisclosed #1
Sep 23, 2017
IPVMU Certified

A grandpa with a shotgun would, I think, be a good solution.

Grandpa would still need additional illumination :)

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U
Undisclosed #4
Sep 27, 2017

Knightscope has a security robot, you can call him grandpa.

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JH
Jay Hobdy
Sep 22, 2017
IPVMU Certified

 

 

 

 

Here is an example of the results we have had with tags. This is real world, unedited. The first camera was a camera the customer got with a previous integrator. We left the camera and installed ours underneath it. Our camera was zoomed in.

 

This is a Speco camera but we get the same results with Uniview cameras and I would recommend them. The Univiews will be hard to find, as they are dealer only. This model is only carried by a couple distributors.

If you can't find someone local to help, we would love to help remotely. Just let me know and I can get my info to you.

 

 

UM
Undisclosed Manufacturer #2
Sep 23, 2017

We use our AVIGILON Bullets with IR on a regular basis to capture number plates either using digital zoom during playback or for LPR purposes. When used as an LPR camera we supply the SI with a document with instructions how to modify the cameras setting for LPR purposes. The request for number plates at site entrances is one we have at nearly every site we come across, same as filling stations etc. so it's one we deal with all the time. Make sure your pixels on target calculations are done right and you should be able to fix your issue.

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UI
Undisclosed Integrator #3
Sep 23, 2017

Would an Avigilon camera work in this instance, based on your SI settings without IR?

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UM
Undisclosed Manufacturer #2
Sep 27, 2017

I would prefer the IR supported option in this scenario.

Avatar
geert Huisman
Nov 05, 2017

I am in interested in using the avigilon for LPR purpose or number plates at site entrances. what is the best route to follow

JH
Jay Hobdy
Sep 23, 2017
IPVMU Certified

How are these cameras monitored? 

Are these cemeteries closed at night?

 

I am wondering if there is anyway to use line crossing, or thermal detection to see if there is activity at night? Try to find a way to stop the theft in action, before they get away.

 

KK
Kamen Kostov
Sep 25, 2017

Was wondering the same thing as well. Capturing license plates at night or dusk is very challenging. Hopefully Axis will provide some information. A while back I had a chance to visited Axis's main demo lab outside Boston. I specifically asked if there are filters that can block car headlights and at the same time allow some IR light come in. Unfortunately I didn’t get a good answer.

Some research needs to be done on the spectrum of light being emitted by halogen/xenon headlights and the same from the tail lights. Then a bandpass filter needs to be installed blocking this light but allowing shorter wavelengths IR light to come through. Lastly an IR illuminator above that range needs to illuminate the scene.

This should allow capture of license plates. Has anybody had good experience doing this at night?

Avatar
Brandon Knutson
Sep 26, 2017
IPVMU Certified

I just replaced a couple of Axis P3367 cameras that were terrible in dim street scenes. I tried everything adjustment wise. Forget about license plates, I couldn't even figure out make and model of passing vehicles.

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Brandon Knutson
Sep 27, 2017
IPVMU Certified

FYI, I'm no Axis hater. My above post was made because the original poster was also trying to use the same Axis P3367 for street use. I really like Axis products, but this older 5MP model doesn't like low light scenes.

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Avatar
Skip Cusack
Sep 26, 2017

In low light I would make some changes to the settings you've shared: 

Auto Focus - Off (probably fine)

Wide Dynamic Range - Off - ON. Why run without WDR? 

Allow Slow Shutter - Unchecked. CHECK. In low light the camera will want to take more time to collect enough signal for a meaningful SNR. I understand the license plate may be moving which will lead to blurring. If possible position the camera where the car slows or stops, even if you have to introduce a road block or chicane to force the issue. 

Enable Highlight compensation - Checked (probably fine unless target is blurred)

Day Night shift priority - Night (good)

Noise reduction - Off - ON. With so little signal at twilight, the amp will rail up the gain and introduce noise. This can be mitigated, especially if the target is not moving much.

Bottom line, low light and LPR are a bit incongruous. You may have to get creative. Get the car to slow or stop in one place. Put some light there with a fixed IR illuminator if you can. Set up the camera for low light especially if you can't illuminate the scene. Then get your photo. Of course there's nothing like a few good dry runs to experiment.

Good luck!

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Avatar
Paul Grefenstette
Sep 27, 2017

Without IR you will never get the plate at night or dusk - go raytec or illuminar -- what is the distance from the plate to the camera and what is your exposure setting?  We use 3mp IR Avigilon 9-22mm under 50' with Raytec IR

I believe you can run openalpr on that axis camera which would start building a plate database in the cloud but you must have it connected to the net obviously.  First things first tho get a decent IR illuminator 

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Avatar
Jubal Routley
Sep 29, 2017
IPVMU Certified

We (Infiniti Optics) use NIR (Near Infrared) technology to cut specific wavelengths from the image. This allows you to get a crisp image that is not as affected by headlights and other atmospheric conditions such as fog. This could work well for your application.

Feel free to e-mail me for more information. Thanks!

jroutley@infinitioptics.com 

JH
John Honovich
Sep 29, 2017
IPVM

Jubal, your products look incredibly expensive for the relatively straightforward tasks of capturing a license plate, e.g.:

What exactly are you recommending for this application?

UI
Undisclosed Integrator #3
Sep 29, 2017

I would think the one on the left would do just fine!

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U
Undisclosed #1
Sep 29, 2017
IPVMU Certified

Jubal, your products look incredibly expensive...

This project's got money to urn...

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Avatar
Jubal Routley
Sep 29, 2017
IPVMU Certified

Indeed, the models in the picture above can be quite expensive as they are military grade models. We also offer commercial/industrial models that could possibly be within Nick's budget. While our models will likely be more than the Axis Q6045, if it isn't working for his application then he could take a look at some of our lower cost models.

I also mentioned it because Kamen was interested in something that cuts certain light wavelengths, which is basically what we do.

Avatar
geert Huisman
Nov 05, 2017

would like to receive more info

 

geert@innotechbv.com

U
Undisclosed #5
Sep 29, 2017

Look at the XNO-6120R from Hanwha. X-Series handles tough lighting very well.

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U
Undisclosed #6
Sep 29, 2017

1.) No surprise that the P3367 image is bad at night if there is no additional lighting. The higher the resolution of the camera, the worse the images in low light will be. While the P3367 is a phenomenal camera, it also doesn't take advantage of any of Axis' newer technologies like Lightfinder. Funny enough, the less-expensive P3227-LVE would likely be a better fit, although I have not done a head-to-head in low light -- I would just be willing to bet that it's a fair margin better.

2.) I will echo the poster above who said that without IR, you are unlikely to consistently get anything. No matter what you do, you need to add IR to the mix. Spend you money there regardless of the camera you're using to capture.

3.) My recommended solution --

Perform a pixel density calculation to determine the lowest resolution camera that you can get that will provide at least 50 pixels on target (not 40 as some suggest) with only the exact field of view of the entrance. I would personally replace the PTZ unless it is used for a very specific reason that I'm not aware of. If you can find a camera with built-in IR that will reach the distance AND also has a lens that will get the density you need, go that route. As an example, HERE is a link to a cemetery in Greenfield where I've placed a camera 60 feet from an entrance at full zoom with an Axis P1425-LE bullet camera with built-in IR.

The IR range of 66 feet is within the range and the camera is producing 53.7ppf with a field of view only on the drive itself. You need to ensure you have no more than about a 20-degree offset to the street, and ideally the camera would be no higher than 8 feet.

Also, the camera should be set to black and white mode 100% of the time, with the IR illuminator active 100% of the time. The illumination that you get from the IR with B/W will ensure that the plate is visible regardless of the amount of light available.

If you can't get that close, then get a box camera with a bigger lens (i.e. Axis P1365-E MKII with a Theia 9-40mm) and an external IR (i.e. Axis T90B20/B30/B40) to reach a minimum of the specifications above.

My personal approach to license plate capture is that anything tasked with capturing license plates is a unitasker. Don't try to do anything else with that camera. Yes, that means it gets a bit more expensive because you often need a license plate camera and an overview camera, but you're unlikely to have consistent success otherwise.

Good luck.

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U
Undisclosed #5
Sep 29, 2017

I disagree. It isn't a matter of resolution, it's a matter of pixel density on imager and quality of imager. There are plenty of 5mp 1/1.8" imager cameras that will outperform their smaller imager, lower resolution counterparts. A 5mp 1/1.8" imager will drastically outperform a 5mp 1/3.2" imager no matter how much marketing jargon you throw at it.

Anything with the 1/3" 2mp and 4mp imager typically won't be the best for low light. I think many of the low end cameras are utilizing this same imager.

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U
Undisclosed #1
Sep 29, 2017
IPVMU Certified

Yes, in general agree with you re: pixel pitch.

An interesting recent test of high resolution and big sensors is 

Axis vs Sony Super Size Shootout (Q1659 vs SNC-VB770)

U
Undisclosed #6
Sep 29, 2017

I'm not saying you're wrong, because you're not, but you're also not exactly "right" as far as I'm concerned either.

1.) Fundamentally, yes, it is about resolution. The more pixels you have in an image, the more light is required to illuminate those pixels. So, all things equal, the image with a higher resolution will require more light than one with a lower resolution. I don't think there's any disputing that.

2.) I do agree that imager size is a good measurement as well, but it's not AS important in the scenario that I outlined above. The 1/2.8" imager in the Avigilon 3MP box cameras works amazingly well for the exact scenario I'm referencing, as I've done it a number of times. I would say that imager size should be a tiebreaker, but I don't think it should be the only consideration. And, I would still err on the side of the lowest resolution that could accomplish the pixel density that is needed for the application. Not only does it decrease bandwidth, it just gives you the best chances for success in all conditions.

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U
Undisclosed #1
Sep 30, 2017
IPVMU Certified

So, all things equal, the image with a higher resolution will require more light than one with a lower resolution. I don't think there's any disputing that.

If the pixel pitch (size) is equal between the high and lower res cameras, then each pixel needs the same amount of illumination.  

It just takes a proportionately larger sensor.

I don't think there's any disputing that.

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