Why can't I read this license plate?

[cachecreekcctv 0]

Tried to upload pic today. Got the same error message also.

[Scruit 0]

I have a home-made LPR setup that captures about 90% of plates 24x7. IT has an IR illuminator and IR filter so it doesn't get blinded by headlights. The illimnator lights the plate up really nicely dusk to dawn.

 

I also aimed the camera at the thinnest section of my driveway so I know where the car will be, so I can zoon into the width of the car.

 

All of the plates that I have missed fall into the following categories:

 

- Car has no front plates, drives in forward, backs out. Our mail carrier does this, so does the electric meter reader.

 

- Vehicle with license plate mounted to extreme left or right. UPS trucks are bad for this. The dump truck that brought my driveway gravel was the same - plate was mounted to the extreme left, behind the wheel of a vehicle that was wider than a car.

 

- Smoked licence plate covers

 

 

The setup work fine for me right now, just a residential setup. Not worth me freaking out and spending anouther coulpe hundred bucks every time I miss a plate. Did that for a while and wasted a lot of time. My two biggest issues were getting the car in a preduictable spot for a close zoom, and reading plates in low light / blinded by headlights. once I fixed those two issues my plate reading success jumped out to 90%, but there will always be exceptions.

[tesfeld 0]

Scruit, I am trying to duplicate the suggested setup, but can't find IR filters or filter material anywhere. Could someone point me in the right direction?

[Scruit 0]

Scruit, I am trying to duplicate the suggested setup, but can't find IR filters or filter material anywhere. Could someone point me in the right direction?

 

 

Got mine from ebay. My lens is threaded for 52mm, so I did a search for "52mm 850nm"

 

http://search.ebay.com/search/search.dll?from=R40&_trksid=m37&satitle=52mm+850nm&category0=

[jeffpa 0]

The guy I talked to said with the Lens I ordered, I'd be good up to 100ft. no problem.

 

I've also noticed that if the plate is either old or dirty, it is completely unreadable as well.

I tried the 80ft route and got almost 100% capture.

 

I got a different lense, set at 20 ft ,because it has a slightly wide FOV.

 

Capture rate 99%.

 

Only failures in capture are due to old or dirty plates, as the Reg series

are highly dependant on the IR reflectively of plates for night time capture..

 

Also some people use the plastic plate covers, which also deflect IR.

[cctv_down_under 0]

There are so many things to consider when doing licence plate recognition that it is often left well alone...here are some things that I have learned with it.

 

1/ Your camera will need to adjust shutter speeds on the fly and keep in mind that when doing this your light level exposure will change accordingly, also to avoid motion blur you need to be careful, if your shutter speed is too low then motion blur will occur on fast moving objects, and if set too high then you will need much more light, so having a camera that can adjust on the fly is imperitive.

The best cameras can adjust shutter speed according to light level...IE it sets the best speed based on available light and when that light deteriorates then it will adjust the shutter in increments until it finds a balance. You will need at least 1/500 shutter speed to read the plate on a fast moving vehicle.

 

2/ The license plate characters must take up a minimum of at least 5% of the monitor height for display identification and for digital recording the plate must be a minimum of 30 pixels in height before you add compression.

 

3/ Recording resolution of your DVR will matter, because this can be the difference between being able to read the plate or not.

 

4/ Compression really counts, some compressions take objects of the same contour and texture and compress those pixels most, flat objects can often be overly compressed unless the contrast between character and plate can be amplified or inverted.

 

5/ You need a camera that can handle the bloom effect and vertical smear associated with headlights of vehicles

 

6/ Your going to need to set a peak level for white, so that it does not affect the range of your camera, IE a wide dynamic range camera with programmable mask will help.

 

7/ Zooming in from distance affects the Field of View, so getting closer really can help.

 

8/ Do not use much gain at night time, gain will amplify the brightness of the headlights, you will find that the best result will occur when you actually set the camera so low in gain and peak that the picture is almost black until a car goes past, the MOST common mistake is to park a car with headlights on and use that scene to get the setting right for a camera, you will inveriably try to allow for too much lighting to ID more than the plate, the lights from the car will definately light up enough for the plate to be seen so it is best to set all your settings to low.

 

9/ Full TV Frame recordings will not have an interlacing effect and therefore a good de-interlace must be used for fast objects if your DVR can not record a full frame.

 

10/ Remember that light reflects and that angle is critical, remember also that asphalt has little to no, scene reflectance.

[Scruit 0]

Here's an example image from my home-built setup:

 

 

This is using a $100 hi-res B&W camera, 50mm zoom lens, 850nm IR filter and a matching 850nm illuminator. The car is about 80' away from the camera when it's being captured.

 

I'm still playing with the design - off and on for about 4 years - I have a auto-iris 50mm zoom lens on order and I'm hoping that will improve the night time recognition. I can capture plates at night, but when everything is dark the compression creates a bunch of colorful artifacts on the screen.

 

I would advise purchasing a true LPR before hacking together a homebrew like mine. It's only just reached 90% capture rate in the last year or so and I usually spens a couple hours a month adjusting it in response to missed plates.

 

This car approached my house and left a flyer. I was in the back garden and never heard them.

 

[rory 0]

where's the night picture though .. or is that at night?

 

Anyway, as you can see it can be done without an LPR specific camera, but for someone making a living out of it, its really not worth the extra time, when there are so many other things they should also be doing.

[Scruit 0]

where's the night picture though .. or is that at night?

 

Anyway, as you can see it can be done without an LPR specific camera, but for someone making a living out of it, its really not worth the extra time, when there are so many other things they should also be doing.

 

I'll get a picture tonight.

 

 

I have older pictures, but what I did recently was move the aim point of the camera about 10' closer to the house, making everything appear bigger on the screen. The illuminator only lights up the license plate - but it lights it up very bright so reading it is very easy.

 

EDIT: Wait, I found one of my test images from the most recent adjustment...

 

 

This is staring directly into the hi-beams also - and the plate is still very clear.

[rory 0]

Cool man.. she looks good

 

Though like you said .. you spent alot of time on it .. most installers cant charge the client enough to keep going back and forth to the clients location over and over ... man after all that labour and gas, they may as well just get the LPR one time ..

[Scruit 0]

Cool man.. she looks good

 

Though like you said .. you spent alot of time on it .. most installers cant charge the client enough to keep going back and forth to the clients location over and over ... man after all that labour and gas, they may as well just get the LPR one time ..

 

Agreed. If I had known how much time I'd be putting into tuning this camera I'd have gone with a true LPR from the start, or simply not tried for LPR functionality.

[rory 0]

Cool man.. she looks good

 

Though like you said .. you spent alot of time on it .. most installers cant charge the client enough to keep going back and forth to the clients location over and over ... man after all that labour and gas, they may as well just get the LPR one time ..

 

Agreed. If I had known how much time I'd be putting into tuning this camera I'd have gone with a true LPR from the start, or simply not tried for LPR functionality.

 

just throw down some spike strips attached to a siren and run out there with your camera when it goes off

 

or put a wireless camera on a dog and let them chase around the cars .. you will even get the underneath of the car then ..

[Scruit 0]

just throw down some spike strips attached to a siren and run out there with your camera when it goes off

 

or put a wireless camera on a dog and let them chase around the cars .. you will even get the underneath of the car then ..

 

Nah - I need a little RC car on autopilot that will chase him down the street.

 

 

I joked with a friend of mine a while back; "What if your home security system had a remote controlled plane that was launched when the alarm goes off, then flies around following anyone who leaves your house."

 

We laughed about that, right up until I saw the Isreali, British and US police are all running pilot programs (no pun intended) of autonomous helicopter drones that will launch themseves and hover at a couple throusand feet while an operator operates a PTZ to watch events from above - riots, disasters, missing persons etc.

 

Missed my chance - should have developed it myself.

 

http://news.bbc.co.uk/1/hi/england/merseyside/6676809.stm

[rory 0]

the way consumer electronics go, and false alarms .. we'd probably have alot of planes dropping out of the sky ..

[Scruit 0]

the way consumer electronics go, and false alarms .. we'd probably have alot of planes dropping out of the sky ..

 

Especially when you buy cheap OEM drones from eBay.

[Ivica 0]

Have You tried to do it with Megapixel IP cameras?

 

I can send You pictures over day and night.

[Scruit 0]

Have You tried to do it with Megapixel IP cameras?

 

I can send You pictures over day and night.

 

I'd need an NVR for that, right? at the moment my setup is all analog/RG6/BNC but starting now I'm going to install new cameras with CAT5/baluns so that I can upgrage to an NVR in the future. I saw a really nive DVR/NVR device the toher day - can take analog or IP cameras - and I'm sure as IP prices drop I could get much better quality from that.

 

The other advantage of running cat5 is I can send the power downt he same wire and not rely on local power - meaning I can run the cameras off the same big UPS as the DVR. And I also have 2 or 4 wires left for running a motion sensor near the camera, or possiblly for remote-triggering a ligth near the camera. Using a true motion sensor would be more reliable than visual motion detection (that's always being triggered by rain/snow/insects etc) for the close detail cameras over the doors.

[Ivica 0]

Yes, You need a NVR or a Hybrid solution. I know, that NetAvis, an Austrian/Hungarian company has all things You need. They can do Hybrid (analog via GrabberCard) and/or pure IP solutions. From IP in CIF format up to 5MP. Every channel can be set up for licence plate recognition. The LPR is an option. If You need contacts, let me know!

 

Regarding triggering:

Most of the cameras themselve have a TriggerInput, where You can directly connect an IR PIR sensor; but with a LPR the better solution was to connect that input to a Inductive Loop in the road. Much better solution, almost False-Alarm-Free.

If You want to have a really good LPR You need to work with IR. I can send You pictures with/without IR, made with a Megapixelcamera, judge Yourself! IR is not so expensive!

 

Working with Software-MotionDetection is really not a very good solution, but working with a Hardware-MationDetection is ok, but very hard to adjust. You have to come to the installation site several times to eleminate all false-alarm factors. I had once a look at that at an Airport installation - lot of money, but...

 

You could do it with a LaserScanner from the company SICK. 1 Dimension-scanning, triggering with two areas (logic combinations) - together with LPR... but again, pricing...

 

Ivan

[kao 0]

I can send You pictures with/without IR, made with a Megapixelcamera, judge Yourself! IR is not so expensive! Ivan

 

You should post pics for all of us to see!

There is a section for posting videos and pictures...or do it here. Also tell us what cams/lenses/software/etc... The more info the better.

[Ivica 0]

Here are two pictures, one with IR and one without, both done with the IQeye752, a D/N 2 Megapixel camera from IQinvision. It could be a 1 Megapixel, not problem at all.

Its a Electronic Tollroad, where cars just driving through. The speed: between 30-60kmh (19-37mph).

The shutterspeed was 1/200, and the gainstyle like Average. The Exposurewindows was set to the whole picture, Gainspeed to medium. The lens was an IR corrected one from Tamron. The NVR was triggered by the inductive loop, but anyway, the car with its Licenceplate can be seen from at least 20m, no really triggering necessary.

 

The picture without IR was not OK for LPR, not enough contrast on the Licence Plate.

[kao 0]

Awesome! thanks for the pics. I love seeing pics and videos from "in the field" and not some manufacturers website where everything looks pristine.

[Ivica 0]

No problem! I have a lot of pictures, real installations, so when I see a related topic, I will jump in and post them!

[megavolt512 0]

Hey guys thanks for all the great information! This is one of those threads I'll have to re-read many times. I've already improved the LP readability considerably by changing the zoom and adjusting the level down.

 

On a similar note, I was looking up close at one of the many toll booths they are building here in Texas. They pretty much have it set up to photograph every single plate. They appear to be using strictly still digital images with a flash (even in the day time). It looks like fireworks with many vehicles blasting through the toll-tag lanes (where you don't have to stop).

 

Haven't seen much mention here of digital still for LPR.

[Scruit 0]

Hey guys thanks for all the great information! This is one of those threads I'll have to re-read many times. I've already improved the LP readability considerably by changing the zoom and adjusting the level down.

 

On a similar note, I was looking up close at one of the many toll booths they are building here in Texas. They pretty much have it set up to photograph every single plate. They appear to be using strictly still digital images with a flash (even in the day time). It looks like fireworks with many vehicles blasting through the toll-tag lanes (where you don't have to stop).

 

Haven't seen much mention here of digital still for LPR.

 

 

A digital still, especially from a megapixel IP camera, would be an excellent way of capturing the plate - it should even allow for the capture of a plate in the wide turn-around spot from the original picture - assuming all other things are correct such as lighting and the plate not being intentionally obscured. A regular analog camera is not going to reliably read a US license plate (after the image is compressed

and the decompressed for viewing) unless the car takes up almost all the frame. You can't just point the camera at the car, look at a live image and expect that same quality on playback. Whenever I set up a camera, especially my license plate camera, I always check the playback quality.

 

Megapixel IP cameras are in the $1k range to start with, and unless you have terabytes of hard drive space you can't run a megapixel image as a realtime video. You still have the other issues like lighting / dazzled by headlights etc.

 

I have a driveway alarm that signals a computer attached to my CCTV system to email me a picture of any car that enters my driveway. If I had a megapixel IP camera then I'd have it take a picture with that instead, but only when triggered by the driveway alarm. I'd still have a regular camera showing the driveway overall and what is happening.

 

 

I did try taking a picture of a car in my driveway using an old 2.1 megapixel digital camera (not CCTV camera, just consumer handheld) that produces a 1600x???? image - very nice. Of course my 8MP camera can take a picture of a car from 50' and I can zoom in to the image an read the make/model from the emblems on the back of it.

 

For the big turnaround area in your first post I'd try to aim the camera at the tightest bottleneck (the road before the turnaround?) and use a zoom len and a VERY good hi-res camera. If you have the $$$, that big area screams out for a megapixel camera.

 

Of course, you could have what happened to me recently - some guy came into my driveway to take a close look at the car parked near my house - and his license plate was covered with a piece of paper...

[Guest]

Here is a few shots from a late 2002 project.

 

Inclueded a link to a video clip as well, it is in Mpeg1 so should be easy to just copy and paste into Windows Media Player.

 

Video:

www.dvr.no/published/carplatempeg1.mpg

 

Picture 1

Taken from a photo camera of the GUI, you can read the number here too.

 

 

Picture 2

Taken from a photo camera of the outside cameras, not the cameras we usually use, but they wanted some cameras matching the 200 000,- USD roof.

 

 

This has been working good for 5 years soon and it is good quality 24 hours a day. It have good help from the outdoor lights!

 

 

Angle, camera, lights, and how big is the plates on the recorded files and what compression and how much compression!

 

 

JD