Posts Tagged ‘ cameras that recognizes license plates’



How to Setup a License Plate Capture Camera

Written By:
Thursday, February 13th, 2014
TP-LP700 License Plate Capture Camera

I often get asked how to best capture a license plate from a vehicle with a camera system. I generally tell the customer that it is done with magical leprechauns, the tooth fairy, and a dash of pixie dust! Then when I get serious I will go into the long explanation of the proper setup to capture the image. With license plate capture there are several things that need to be considered and in place to be able to capture a license plate on a vehicle. You need to be between a certain height and angle, need to be focused on a concentrated area, need speed control of the vehicles, and need the proper camera.

The Right Height and Angle

With any camera, the right angle and height are very important when trying to achieve specific shots. A license plate capture camera is no different, and actually it is more important than most. There are several schools of thought as to what is the idea height and angles for this application. The one that I have found works the best, is to ensure the camera is between thirty six inches from the driveway up to ten feet. The height of the camera plays a big role in how clear the image will be, if the camera is too high and the vehicle has some sort of plate cover on it, you can get an image that is too distorted to make out.

If you think about it, most vehicle license plates are between twenty inches and forty eight inches from the driveway surface, so you don’t want to create a crazy angle to try and capture a license plate from. Another important thing to remember is how far off the lane of travel the camera is situated, this plays into the angle created on the capturing of the image. Typical rule of thumb is to have the camera as close to the lane of travel as possible. So the closer to the curb the better!  Now, I know you are asking yourself, “what if someone comes up and vandalizes the camera?” Well, the way to help protect this is by having a camera that watches over the location of the license plate capture camera.

Focused Area of View

Another big factor in license plate capture, is not trying to do everything with one camera. In order to properly capture a license plate, the camera needs to be focused on one lane of travel. So, if you are trying to capture multiple lanes of travel you will need as many cameras as lanes you are trying to capture. A good rule of thumb is to have a camera per lane and a camera that gives overviews of the area. The overview camera will give you the description of the vehicle, while the license plate capture camera will get the license plates. If you try to do too much with one camera you will fail at doing anything useful except get a description of the vehicle. It may cost you a little more upon initial setup for the extra camera, but what you will gain with useful information is priceless!

Speed Control

A very important factor to be considered is the speed the vehicle will be going. If you have a vehicle that is traveling at a high rate of speed and you expect to capture it’s license plate you better plan to spend some very very big dollars on a camera. Now if you are realistic and have an area where a vehicle has to slow down or even better stop, you will be in tall cotton. The most ideal way to capture a license plate from a vehicle is to have an area where the vehicle will have to come to a complete stop. Whether that is at a stop sign, a severe speed bump, or a gate that has to open does not matter, as long as you can get a vehicle to stop. The next best solution is where a vehicle has to slow down extremely, ideally under ten mile per hour or so. Now if you do not have the ability to slow the vehicles down, you are going to have to look into the cameras that most interstate systems use which generally cost in the thousands of dollars per camera.

Proper Camera

Barring needing a specialty high speed camera that interstate systems use, you can generally find a good camera with a reputable company. The right camera will depend on several things. The first and foremost is the distance from camera to target. Why this is so important is because you need the right lens to narrow down on your target. If you are at thirty feet and trying to use a 2.8mm – 12mm varifocal camera and narrow the shot down to a eight foot by eight foot area, you will fail. This is because at a thirty foot distance to target and the camera zoomed all the way to it’s 12mm setting, your area of view is going to be over ten foot by eight foot. This generally will be too wide of a shot to capture a clean enough image. I personally would suggest going with a 9mm – 22mm lens for anything over twenty feet to about forty five feet. For any shot that is from about fifteen feet to about one hundred and twenty five feet you should use a camera with a 6mm – 60mm lens. If you are unsure of the millimeter lens that you will need, you can always use the lens calculator on Security Camera King’s website.

If your project meets all of these requirements, your license plate capture should occur with minimal issues. With every job and every location there are different obstacles that will be needed to be overcome, no two jobs will ever be identical especially when it comes to license plate capture. The best thing you can do for yourself is to survey the area, taking lots of pictures and measurements. Find any possible available power source and possible areas to burry conduit to get to the camera location. Keep in mind to always obey local codes and pull the necessary permits. The last thing you want to have happen is an inspector/ code enforcement officer to flag the site and cost you time and money.

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License Plate Capture Camera vs License Plate Recognition Camera

Written By:
Wednesday, January 2nd, 2013

License Plate Capture Camera vs License Plate Recognition Camera by Ryan Newkirk

When talking to clients about the requirements of their security system, I often run into business owners and homeowner associations who are looking to place a security system at an entrance or exit to view vehicles coming into and leaving from their establishment. One of the biggest things that I have learned to do, is to inquire about what they expect to be able to accomplish with this camera system. The reason why, is that a lot of people assume that license plate capturing and recognition are one in the same. What the general public needs vs. what government agencies need are typically two totally different things. The general public typically only needs to be able to capture an image of a license plate, whereas a government entity and some corporations need to be able to not only capture a plate but also recognize the information on the plate in realtime. There is a difference and you can’t do recognition without capture and I am going to explain the differences.

License Plate Capture

The majority of consumers looking to monitor vehicle traffic at their location, will only need to be able to capture license plates with a camera. To capture means to record an image of the information for future use when needed. In order to properly capture a license plate you should have a traffic calmed area, generally a gate or stop of some sort. This is to give your system a better chance to get a useable image of the license plate. To ideally accomplish a license plate capture, you should only strive to cover one lane of traffic per camera. For the best possible shot the camera should be mounted at a lower level than you would normally mount a camera, approximately 36 inches from the height of the street and as straight on as you can get without being in the lane of travel. This camera will be used only for the capturing of the license plate image and you should use another camera in conjunction for an overview of the vehicle to acquire details, such as color and make. This is only part of the equation, you will want to make sure that you recording unit can do D1 resolution at 30fps for the best chance to capture a usable image. Also, the camera that is being used will need to have features for eliminating interference from lighting sources and a varifocal lens for narrowing the field of view.

An ideal camera for license plate capture will have what is referred to as an on-screen display (osd). In a camera that is suited for license plate capture there are settings in the OSD to help reduce the interference of headlights or taillights. Generally it is called headlight compensation (HLC), what this feature generally will do is give you the ability to select regions in the picture zone that you want to have lighting filtered out to help prevent interference of the plate region. Most cameras have boxes that you are able to move into place. When setting up these regions, you will want to place a vehicle in the lane to place the boxes in the areas where the headlights and taillights will travel through. Make sure to leave an area large enough to accommodate the possible areas that a car will travel through, this is because not all drivers will pass through the lane in exactly the same spot.

There are typically two styles of cameras that work the best for this application, bullet and box cameras. You will want a varifocal camera with enough zoom to tighten the picture up just wider than the lane of travel. The amount of varifocal you will need is dependant on the distance the camera is mounted away from the target location. For application where the camera is within 50 feet of the target a 9mm-22mm lens will be sufficient. You can find really high quality bullet cameras that have this size lens and generally will have infrared (IR) illuminators built in to help with nighttime capture for reasonable prices. Just make sure that whatever bullet you choose has the OSD control with the HLC options, built in. If your target is at the far end of this distance and beyond you will want to look into a box camera solution with a larger varifocal lens. Typically when you are buying a box camera, you will buy the camera, the lens, and the housing all separately. This will allow you to get the correct lens and camera for your situation. If you need more light on the plate area, there are separate IR illuminators which can be used in conjunction with most cameras. You just want to be cautious not to over illuminate the plate causing it to be unreadable caused by IR washout.

Now that you have your system in place and your camera setup, it will take some tweaking of the OSD configurations to get the nighttime and daytime image to meet your needs. For this fact, I like to use a camera that has an RS485 connection on it that I can run back to the DVR and control the OSD functions remotely. This way you can remotely login to the system at various hours of the day and adjust the settings until you get the best quality image you can under all circumstances. Once you have got your system setup exactly the way you want, you are ready to capture the license plates of the vehicles coming into and out of your property. This is called capturing because the information will only be stored in the DVRs recorded footage and not accessed unless it is needed. If you need to register or log the information you will need to have recognition as well.

License Plate RecognitionLicense Plate Capture Camera vs License Plate Recognition Camera

With license plate recognition, you need to be able to capture the license plate information and have a system in place to read the captured information and process it. There are several ways that this can be done. One way is to have a system setup like in the license plate capturing process and have the video stream from the license plate camera going into a computer system. This system will then take the images and analyze the plate information in a process called License Plate Recognition. You can have the system analyze the information against a known database, for use with access control. There are services out there that have access to larger known databases that the information can be checked against.

There are even more sophisticated systems out there that are all self contained in the cameras themselves. These systems have a camera dedicated to do nothing but record all of the plate information for every vehicle passing in its view. They can then just store the information or transmit the collected data to an offsite location for further analysis. This type of system is often used when government entities put up red light traffic camera and toll road cameras. When the system is used for a red light camera application, there is a camera that is always recording the intersection and one that snaps a very high definition picture of the intersection at the moment the sensors dictate. These scenarios have multiple cameras at the corners to capture both directions of travel. The information is generally stored at the location and transferred back to a centralized computer based on the companies schedule. This type of setup is often used with toll roads to help catch toll violators and can be done at much higher rates of speed.

Some law enforcement agencies have implemented a newer technology that not only does the recognition, but it does it in real time. This offers the officer the ability to catch offenders of a variety of different crimes in their tracks. These systems are generally mounted in the trunk of the vehicle with cameras that are roof mounted with a 360 degree view. Allowing the officer to patrol as normal with the system doing all of the work notifying the officer of any potential problems.

There is a difference between capture and recognition, I hope that this will better clarify what you may need. There are not too many entities out there that need recognition. Most can settle with license plate capture and if the information is needed it can be retrieved. Normally you will only need the information when a crime has been committed, otherwise you will be able to go on with your normal day to day surveillance.

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