How to Setup a License Plate Recognition Camera System

License plate recognition cameras are a staple for outdoor AI-based security camera systems. Keeping a track of all the cars going in and out of your site is crucial in keeping it secure. However, installing and setting up an LPR camera is not as simple as setting up a regular camera for surveillance.

This blog talks about setting up an LPR camera and what you should consider to ensure that your camera license plate captures the maximum amount of cameras.

If you have thought about or researched LPR cameras, you may have realized that it is unlike any other security camera installation. While some people are put off by complex formulas to figure out camera angles and ideal locations, all of the process can be simplified once you understand how LPR cameras are to be set up to get the best performance. For general guidance, you can refer to our guide on how to install a security camera.

LPR cameras are placed at spots where cars would slow down enough for the camera to take a clear picture of the license plate with sufficient lighting.

Once an LPR camera captures an image of a vehicle’s license plate, the plates are read through Optical Character Recognition (OCR). Through OCR, security cameras are able to differentiate between and recognize characters. They can not only read the text, but also understand and adapt to various changing designs of license plates. These plates can then be stored in a database to cross-reference when required or just to keep track of who comes and goes. Integrating video analytics in security cameras can further enhance the capabilities of LPR systems by providing real-time data analysis and alerts.

LPR cameras are used mostly for law enforcement, parking management as well as access control systems.

With varying vehicle speeds, it is difficult to capture license plates. Some vehicles move by faster while some take their time, which makes it difficult to have one setting to accommodate all of the scenarios especially during night time when lighting is an issue and the shutter speed has to be slowed down to get a clear image of the license plate for better readability. Implementing a motion sensor alarm can help enhance the overall security and detection capabilities, ensuring better monitoring even under challenging conditions.

While it is not an issue during daytime, capturing front plates during night time means facing car headlights straight on. This throws off your camera’s exposure settings and leaves you with just two blobs of light instead of a clear image of a license plate.

Knowing and handling these challenges can improve your LPR camera performance. Consulting a security professional that knows the ins and outs of the system can help further improve efficiency of your system.

Setting up an LPR camera can be a daunting task. From finding the right position for it to handling the configurations with NVR and the rest of the system, it involves a lot of integrations and manual settings.

Here are the steps to follow when you are looking to install LPR cameras on your site:

The first step in installing an LPR camera is figuring out where it would go. This essentially is a point where it is easier to capture license plates. The camera angle should not be too sharp so as to give a warped image of the license plate, or too far away that the license plate is not readable.

Ideally, the camera angle from the ground should be around 15 to 30 degrees, while the horizontal angle from the vehicle should be 15 to 25 degrees and the camera should not be too high up from the ground.

Usually this involves doing a bit of mathematics to figure out the right angles and set up the camera, however, you do not have to do this yourself. There are tools available that can do it for you, such as this one from Nelly’s Security. Ideally, it is better if the camera has a large optical zoom so that you can zoom in on a license plate and not have to be too picky about all the angles and distances.

A choke point is a place where the camera would be zoomed in and focused on to capture the license plate. Ideally, it should be a place where vehicles pass through at a slower speed which allows for better image capture. Common choke points include parking lot entrances, toll booths, and one-way roads.

There are a few factors to consider when picking your choke point, which are the following:

Once set up, have the camera pointed towards the choke point and ensure that the license plate takes up more of the frame. It is better to zoom in on the choke point instead of having a general view of the area. You can opt for two different cameras, one for LPR and another for general purpose surveillance for the best results in both.

Now that the LPR camera is set up and ready to capture license plates, it is important to talk about the camera setup, such as resolution, frames per second and other video settings so that your camera functions optimally.

Log into your LPR camera interface using your web browser and the default login and password provided. It is a good idea to change the password once you are logged in to the interface so that you are protected from cyber attacks. Here are a few important settings to change once you are in the camera interface to ensure the best video quality and image captures:

Now that the security camera is all set up, it is capturing and storing license plate data locally. This means that if the browser is closed, your data would also be erased. You would require an NVR in order to view, manage and store the data coming from the LPR camera. This NVR stores all the snapshots onto a photo server for record, through which license plates are recognized.

Having an LPR camera set up is not as simple as installing it and forgetting about it. There are a few considerations when it comes to real-life scenarios that may impede your system’s ability to recognize license plates.

Ensuring a reliable power source is crucial for continuous operation. An uninterrupted power supply for CCTV camera system can help maintain functionality during power outages, preventing any gaps in surveillance.

Additionally, it’s important to be aware of common security problems for commercial plazas, as these environments often present unique challenges that can impact the performance of your LPR camera system.

Following are a few things to look out for when setting up your LPR camera for the optimal license plate capture:

While it is not as big of a problem when capturing rear license plates, when capturing front license plates, the headlights can be a problem at night. This is because the camera’s ISO sensitivity adjusts according to the available light coming from the headlights and is unable to take a clear image of the license plate as it gets blacked out.

While it gets significantly more difficult to capture front license plates with headlights shining right at the camera, here are a few things you can do to make the situation better:

• Try shortening the exposure of the camera to accommodate headlights at night. This would, however, make the overall scene darker as well so treat this as a trade-off.
• You can add in IR or white light illuminators to the mix to moderately help the problem.
• Choose color instead of black and white footage since colored footage significantly reduces glare and helps with the dynamic range of the entire scene.
• Be sure to check multiple resolutions of image capture as well, since a higher resolution captures more detail but also increases headlight glare significantly.

If you have sufficient lighting available, such as during the day time, the camera is able to capture license plates properly, even at speeds of more than 40mph. Adjusting the shutter speed of the camera to accommodate faster moving cars means that you would be compromising on clarity since the scene becomes darker and more difficult to read license plates successfully.

• Set up a trade off and realize that you will not be able to capture all the license plates. Set up a high enough shutter speed so that your image quality does not suffer beyond a certain point.
• The best way to navigate this, is to ensure that your choke point is such that vehicles have to slow down to a reasonable speed for the LPR camera to do its work before they speed off again.

Night time surveillance is always a challenge, however, with a few tweaks and proper ambient lighting at the area being surveilled, you can improve the quality of your LPR system and get the most out of it.

If you have your LPR camera framed to cover a wide area and have license plate recognition enabled as well, the success rate would be significantly lower. This means that one camera with its configuration set to accommodate the entire scene would not be able to read license plates efficiently.

It is best to have two cameras. One for general surveillance, and a dedicated one for license plate recognition. This way, you get the maximum security and your cameras operate at their best settings for both scenarios.

General purpose cameras usually have a 3 to 8 mm lens while purpose-built LPR cameras have between 9 to 22mm. For much larger sites, these can go from 30mm up to 80mm for a much larger parking lot where the camera is placed far away from the parking entry/exit or any other choke point.

Lower light conditions significantly contribute to the blurriness of fast-moving images, especially at night. This is because LPR (License Plate Recognition) cameras rely on adequate lighting to capture clear, readable license plate images. In low light, the camera’s ability to freeze motion diminishes, resulting in blurred images that are difficult to decipher.

For instance, if a vehicle stops directly in front of your wide-angle camera, whether during the day or night, the likelihood of capturing a clear license plate image increases. However, this scenario is uncommon since vehicles rarely stop at the perfect position for optimal capture. Therefore, it is crucial to ensure that your LPR camera is equipped with features such as infrared illumination or low-light sensitivity to enhance its performance in challenging lighting conditions.

To mitigate the impact of low light, consider installing additional lighting sources near the camera or using cameras with built-in infrared capabilities. This will improve the overall effectiveness of your LPR system, ensuring better accuracy and reliability, even in low-light environments.

At night, images captured by LPR (License Plate Recognition) cameras may appear poor due to the lack of light, making it seem like the camera isn’t functioning effectively. However, when a vehicle passes by, the light reflecting off the license plate often allows for successful image capture. Achieving a good balance in camera settings is essential to control the amount of light entering the lens during the day, preventing the image from being washed out. Conversely, insufficient light at night results in overly dark images.

Capturing license plates at night can be challenging, so it is important to consider factors such as megapixels, lens quality, and camera placement when selecting your equipment. Planning is crucial to achieving the best results with your LPR system. Ensure that your camera settings are optimized for varying light conditions, and consider using cameras with infrared capabilities or additional lighting to enhance nighttime performance. With careful planning and the right equipment, LPR cameras can effectively capture license plates even in low-light conditions.