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dvarapala

Licence Plate Cam: Please Critique This Approach

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My goal: to put together a dedicated cam for capturing license plates - manually at first, but with the possibility of going to an automated system later. I really like the Mobotix M12 with the LPF lens, but at ~$2000 that's just way more than I can afford. I'm thinking the following combination would work for less than half the price of the Mobotix:

 

 

Any obvious problems with this approach? Is the manual iris lens going to be a problem?

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What are you recording with? If you think $2k is expensive for mobotix... wait until you see the final project costs on that arecont setup you got going...

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What are you recording with?

 

http://www.zoneminder.com

 

If you think $2k is expensive for mobotix... wait until you see the final project costs on that arecont setup you got going...

 

Well, ZoneMinder is free, and so is manual review of the captured footage. If/when I go to automated capture, I'll be developing the software myself as a ZoneMinder plug-in. There is at least one open source ANPR package I can use as a starting point. But all that is beside the point; regardless of what kind of camera is feeding the images into the system, the back end hardware and software (and their costs) are going to be the same.

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Ahhh... I didn't realize you were interested in ANPR in the future..

 

I have not used Zoneminder, but I get the impression the majoity of the people happy with it have never used anything else? Is that the case? I always felt it was desgined for the tinkerer at heart, and not a business... I could be wrong??

I know with my paid for VMS soltutions, I couldn't run a business without having brilliant people only a phone call away to support the software... lots of variables from an install/ maintinence standpoint. I would imagine there is no dedicated support for ZM? Only forums, Wiki, and Google?

 

I had no idea there were free SDKs for ANPR... Please keep us informed of your progress! "Good" ANPR software we've evaluated in the past ran upwards of $6,000 per lane... just for the software!

 

My thoughts on Mobotix is that there is nothing better for a standalone (video only) solution out there... However throw a NVR (or a dedicated PC) in the loop and it's like why have Mobotix??

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What are you recording with?

 

http://www.zoneminder.com

 

If you think $2k is expensive for mobotix... wait until you see the final project costs on that arecont setup you got going...

 

Well, ZoneMinder is free, and so is manual review of the captured footage. If/when I go to automated capture, I'll be developing the software myself as a ZoneMinder plug-in. There is at least one open source ANPR package I can use as a starting point. But all that is beside the point; regardless of what kind of camera is feeding the images into the system, the back end hardware and software (and their costs) are going to be the same.

 

 

 

dvarpala. this is a subject that always gets to me. when people say thay want to build there own ANPR system. ANPR is a database system and you have to be licenced to use it. are you looking to catch number plates or are you looking for a true ANPR system.

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Zoneminder works great! It is for people who know their way around Linux, and are able to tinker some. The motion-detection is spot-on, but requires a lot of tuning. Evidence downloading is extremely easy. You can download events in 4 clicks, with all the frames as individual JPG's. It keeps every bit of quality from my Analog cameras. Or, you can choose the Video option and download a video of the event in many formats.

 

I just decided to buy a 1TB SATA drive, and set it to Record. Records 10-minute events right after another for each channel. Quality can be set from 1-100, mines at 90, I can keeps a few weeks of video at once. I set the "PurgeWhenFull" filter, so it operates just like any DVR, purges oldest events when HD fill is above 95%.

 

What makes it nice is that it can be ran on almost any computer, I using an OLD Pentium 4 system with about 300MB of RAM! Zoneminder can be installed on many Linux distros, I chose Ubuntu 10.04. I can capture 4 channels at 5-7 FPS each, at D1 resolution. Zoneminder is served by Apache, so its ready to go on most all web servers. I have it set up so I can view from anywhere with DDNS.

 

Probably best of all, it can easily connect to and capture from a plethora of IP cameras. You just need to get the URL of the IP camera that pumps out the raw images, and paste URL into Zoneminder.

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Adam,

 

What other VMS software have you used? What would you compare ZM's ease of use and functionality to anything else out there?

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In the realm of free solutions, I've tried almost all, ZM is one of the best in the free category.

 

Now if your going to pay $80+ for software, of course you will get something that is even more easy to use, and simpler to set up.

 

I would rather tinker for a few hours to set it up - (install capture card, install HD, install Ubuntu, install ZM, test, etc...)

 

I just rave about it because I'm like "Wow, all this is really free?!?" Seems like similar commercial software costs above $100, and you may have to use a newer computer (don't forget OS), and buy a card that costs over $100.

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I believe you!

 

Sounds perfect for your wants/ needs!

 

However, it still sounds like something I would never want to install for a customer.

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That is for sure! Setting up ZM for any sort of customer is not something I would ever do. Too many small tweaks needed... For example, if you want to record cameras above 320x240, you have to edit the shared memory settings in /etc/sysctl.conf. This involves calculating memory that needs to be reserved, so for 4 cameras @ 640x480, you would have: 640 x 480 x 3(RGB) x 40(image buffer) x 4(# of cameras).

 

On a side note...

 

Do any other VMS software support using SSL encryption, as well as .htaccess password protection? Since ZM is used with Apache, I have it set up to always use SSL and .htaccess, (much more secure!)

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I have not used Zoneminder, but I get the impression the majoity of the people happy with it have never used anything else? Is that the case? I always felt it was desgined for the tinkerer at heart, and not a business... I could be wrong??

 

Well, that works out just fine, since I'm a hobbyist and not a business.

 

I had no idea there were free SDKs for ANPR... Please keep us informed of your progress! "Good" ANPR software we've evaluated in the past ran upwards of $6,000 per lane... just for the software!

 

For that price, it had better be six-sigma reliable, and when it does fail, their lead software engineer had better be over at my place in a hour to fix it.

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dvarpala. this is a subject that always gets to me. when people say thay want to build there own ANPR system. ANPR is a database system and you have to be licenced to use it. are you looking to catch number plates or are you looking for a true ANPR system.

 

Forgive me if I've used the terminology incorrectly. I assumed the "Recognition" part was simply the Optical Character Recognition algorithms required to pull the plate numbers out of the video frames.

 

BTW, I'm not the only one who uses the term in this manner. The open source javaanpr package also lacks a database look-up component, and focuses solely on the character recognition:

 

http://javaanpr.sourceforge.net/

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dvarpala. this is a subject that always gets to me. when people say thay want to build there own ANPR system. ANPR is a database system and you have to be licenced to use it. are you looking to catch number plates or are you looking for a true ANPR system.

Huh?? Its a general term used for Automatic Number Plate Recognition Software. I normally call it LPR though.

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I had no idea there were free SDKs for ANPR...

Yes, there are also many for facial recognition etc .. software developers normally use these to cut down on the time it takes to roll their software out and so they can concentrate on what they do best and leave the other part up to others that have already done that part.

 

here are a couple (not free)

http://www.anpr.net/anpr_09/anpr_sw_development.html

http://www.dtksoft.com/dtkanpr.php

http://www.warelogic.com/

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For that price, it had better be six-sigma reliable, and when it does fail, their lead software engineer had better be over at my place in a hour to fix it.

 

Idk... I get the feeling it's some pretty complex software/ algorithims... not something I would think even the brightest MIT kid could do in the whip up in a weekend... I would imagine it's a little more complex than the OCR software that comes with your flatbed scanner.. Maybe I'm wrong?

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I tried Zoneminder... and perhaps my *nix-fu is weak, but I found it to be a royal PITA. The memory tweak that was mentioned up-thread for resolutions >320x240? I've never seen that documented anywhere.

 

Disclaimer: I've been a linux user since the early 2.0 kernel days... and even I found Zoneminder to be a little painful to set up. Don't get me wrong... I got it work... but getting everything to work right was neither simple, nor easy.

 

If you don't have strong *nix skills, you should probably forget it. If you must run your VMS system on a unix platform (and there are plenty of good reasons why you might want to), I'd go with Exacq... it was FAR easier to set up under Ubuntu than Zoneminder.

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I'd go with Exacq...

 

+1.

 

I run Exacq on Ubuntu. Easy to install, and a solid performer. And the iPhone app never fails to impress.

 

Best,

Christopher

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Was the speed of the vehicle and distance mentioned and I missed it?

That is going to dictate a few parameters.

 

Speed is typically 15 MPH or less. I'm at the end of a cul-de-sac, so cars have to slow down somewhat in preparation for turning around.

 

Distance is roughly 30 feet. Also, a straight-on shot is not possible; the camera will be offset horizontally by about 15 - 20 degrees.

 

One of my big concerns was the manual iris lens (and camera) being used in an outdoor environment. While there will be a visible light filter and full-time IR lighting, I can only imagine that there will still be a lot of variation in the amount of light. Does this approach even have a chance of working, or should I forget about the manual iris stuff and go auto?

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Does this approach even have a chance of working.....?

 

 

Depends on your definition of "working."

 

Do you have any other goals other than capturing the plates?

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Does this approach even have a chance of working.....?

 

Depends on your definition of "working."

 

"Working" in this context shall indicate that the camera apparatus can capture a clear image of the license plates on passing vehicles under all ambient lighting conditions.

 

Do you have any other goals other than capturing the plates?

 

At some point in the future I want to experiment with some automated image processing software to OCR the plates automatically. Initially, however, it is enough to capture clear images for manual review.

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As long as you have enough pixels on target and you have enough lighting to contrast/ reflect the LPs you'll be fine.

 

Don't count on the picture being useable for anything else other than plates. Your shutter speed will need to be crazy fast...

 

Let me know if you get a working prototype of ANLPR/ OCR software. We'll go in biz together and make millions!

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Yea...If you did not know this already, LP cams usually look like this:

 

 

It uses a special lens, IR light, and a rather fast shutter speed to get good license plate pictures.

 

If you also want details about the vehicle itself, your need a normal camera as well, probably a TDN camera, maybe even WDR as well (so bright head/tail lights don't blind it).

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As long as you have enough pixels on target and you have enough lighting to contrast/ reflect the LPs you'll be fine.

 

The lighting is the toughest part. I can capture sharp, clear plate images all day long; night time is when the problems crop up. Right now I'm experimenting with IR illuminators...

 

Don't count on the picture being useable for anything else other than plates. Your shutter speed will need to be crazy fast...

 

Through experimentation I've found that a 1ms shutter speed works quite well as long as there is enough light.

 

Let me know if you get a working prototype of ANLPR/ OCR software. We'll go in biz together and make millions!

 

Here you go - start raking in the big bucks!

 

http://javaanpr.sourceforge.net/

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