Setting up an automatic license plate recognition system

To really take advantage of your license plate recognition camera, you need to integrate the camera with dedicated LPR software

Dressed in expensive clothing and driving a shiny Mercedes around the tony town of Tiburon (Calif.), the woman looked like she truly belonged among the affluent residents in the San Francisco suburb. 

However, she was working for an identity theft operation, using her "camouflage" to steal mail from people’s mailboxes. Upon her apprehension by police a few years ago, the town made national headlines when the decision was made to install license plate recognition cameras on the only two roads into and out of town.

Basically, if you visit Tiburon — which reportedly has a median home price of $2.62 million and is ranked by Forbes as one of the most affluent zip codes in the country — somebody in the PD will know about it.

Four Fundamentals
Understandably, commuter criminals were largely to blame for the majority of crimes being committed in Tiburon before the installation of those LPRs in 2009 and consequently, it stands to reason that such crime has since dropped.

Even at the time when Tiburon’s LPR installation caused privacy experts nationwide to go downright delusional with disdain, LPRs were not new, and in recent years LPRs have become ubiquitous in many areas.

But even as their use has skyrocketed, understanding of them has remained relatively static (despite continuing rumors to the contrary, these devices do not snap images of drivers, for example). To get a slightly clearer picture — pun very much intended — I recently connected with Loc Nguyen, a technology engineer for 2M CCTV, a provider of license plate recognition systems and cameras for law enforcement agencies.

Setting up an LPR system is not as simple as just mounting it to a pole and letting the camera do the rest. These things require proper planning and excellent execution to ensure that your investment properly captures, analyzes, and stores license plate data without distortion. In fact, Nguyen said that when setting up an LPR, there are four important factors in getting it to function well:

Camera angle
Shutter speed
Area lighting
LPR software

What follows are a series of brief tips that can help you adjust to any obstacle that may present itself as you set up a pole-mounted LPR, as well as some thoughts on getting the most out of your chosen LPR system.

Camera Angle
“The angle of the camera is essential in capturing the license plate,” Nguyen explained. “The location of the camera can also dictate what kind of license plate camera you are going to get.

“The two main LPR cameras are going to be a box camera with a vari-focal lens or a bullet camera with a vari-focal lens. If the area you are trying to catch is broad, I would recommend a box camera. If the distance is short, I would go with the bullet LPR.”

Nguyen cautioned, however, that there is no exact specification that will work all the time. He says that the best way to find the perfect angle is to set up the camera, and test run it, and make adjustments accordingly.

Shutter Speed
Nguyen said that when you’re looking at an LPR camera on live view, sometimes you won’t be able to see the license plate clearly — which is a particular problem if the vehicle is moving at an excessive speed.

“You should be able to slow down the recorded footage and the license plate should come up clearly. If the plate is still blurry, you would need to go into the camera on-screen-display and change the shutter speed to a faster rate.

“My advice is to gradually increase the shutter to fit your needs. The reason you don’t want to automatically turn up the shutter speed to the highest setting is because it will darken your image and make the image grainy. Once the shutter speed is properly adjusted, the license plate should come up clearly,” Nguyen explained.

Area Lighting
Nguyen says that it’s imperative to take the lighting of the area into account. If it’s a well-lit area during both day and night, then you should be able to capture images without needing a camera with IR or IR illuminators, but if you are using a box camera in a dark area you’ll need IR illumination. The illuminator can be mounted just above or below the camera, and will obviously have to be pointed in the same direction the camera is pointed.

“This illumination will provide enough light to see the license plate,” Nguyen said.

LPR Software
“To really take advantage of your license plate recognition camera, you need to integrate the camera with dedicated LPR software. There are a lot of brands out there but they all basically have the same function. The main function of the LPR software is to store the pictures of license plates into a database. This comes in handy for almost any situation,” Nguyen said.

For example, imagine that this were implemented at a retail establishment and someone is observed stealing and manages to get away in their car. If they drive by a gate that has the LPR camera that is linked to the software, the license plate will be stored on file.

“Once it is stored on file, you should be able to set up an alert for that specific plate. Now let’s say the thief comes back; once he drives through, the camera alert will automatically notify the security guard that is monitoring the surveillance equipment. This will allow for a quick apprehension of the perpetrator,” Nguyen said.

“If you want to get the most out of your LPR camera, it is a must to use license plate recognition software with the camera.”

Two Conclusions
Critics of LPRs — from the liberal ACLU to various libertarian groups — argue that the retention of records on the movement of a law-abiding citizen is an unwanted intrusion into a person’s reasonable expectation of privacy.

LPR proponents counter that such an expectation of privacy goes out the car window as soon as you voluntarily drive on a public road, and that LPR records are rarely kept for more than 30-90 days before becoming totally irrelevant and written over with new data.

Two things are certain, in my humble opinion. First, LPRs are a force multiplier for law enforcement — one LPR system can capture and analyze hundreds of license plates in the time it would take one police officer to do a handful.

Setting up a system such as that which exists on the two entry/exit points in a town like Tiburon can serve to not only apprehend violators, it can serve as a deterrent against criminals commuting to “work” in affluent neighborhoods.

Second, until such time as the issue is seriously challenged on Forth Amendment Constitutional grounds (and that may never happen), LPRs are here to stay.

What do you think? Add your comments below or send me an email. 

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