Ten Factors to Consider when Buying License Plate Recognition (LPR) Cameras

There are two types of license plate cameras on the market: true LPR (license plate recognition) cameras, and standard security cameras that are capable of reading license plates. The second type of camera is commonly known as LPC, or license plate capture.

True LPR cameras usually cost over $1000, have tested daytime and night-time reads of license plates on vehicles traveling at certain speeds, and have the ability to interface with some type of software database which has some type of reporting function. They are generally able to read license plates on one or more lanes of vehicles traveling at highway speeds and have some type of built-in or optional diffusable infrared to illuminate the license plate but not over-illuminate to the point where the reflection is all that is seen. Popular manufacturers of LPR cameras in this category include Messoa, Vivotek, Hikvision, and Digital Watchdog. Dahua offers ANPR (or automatic number plate reader) cameras, but as of the date of this post, Dahua’s offering only includes the reading of license plates (LPs) of vehicles which are stopped at gates; not those of moving vehicles.

Most consumers and small to medium-sized businesses would rather spend no more than a few hundred dollars per camera to be able to read license plates of vehicles going in and out of their driveways, streets and intersections, or entry/exit points, also known as choke points. Infrared is generally not diffusable at this price range. These “fake LPR cameras” are not designed for LPR, so vehicle speeds have not been tested, nor has the effective range or number of lanes.

The configuration of cameras to be able to read LPs in daytime and night-time include adjusting frame rate, exposure, and lighting to coincide with vehicle speeds. In 2016 Custom Video Security was asked by an HOA in the upscale neighborhood of Bel Air, CA to install LPR cameras in two intersections leading into this residential neighborhood to help prevent crime in this area, as well as to identify the owners of vehicles used in conjunction with the home burglaries and home invasions. In the summer of 2017, Custom Video Security replaced three analog SD single-lane LPR cameras with 3MP IP dual-lane LPR cameras by Messoa during an industrial installation in Fullerton, CA. Photos will posted at the end of this article.

Ten factors to consider when researching LPR/LPC cameras:

  1. Price or budget. This is the most important factor because if the budget is not at least $800, then either the end-user expectations need to be adjusted, or the budget needs to be raised.
  2. Reporting and integration. In addition to using some kind of DVR or NVR, there are LPR or ANPR software options on the market that compile a database of vehicle license plates that allow for reporting. Standard reporting features typically include the ability to list or filter license plates beginning or ending with certain characters, blacklisting certain license plates (for example former employees at a company or expelled students at a school), and counting or listing the number of times a vehicle plate has been identified in a given period of time. Our preferred choice of reporting is Milestone XProtect’s LPR.
  3. Output format. There are several types of camera formats on the market: Analog SD (standard definition), HD-SDI, EX-SDI, HD-TVI, HD-CVI, AHD, and IP are the most common. There are several variations of the analog HD formats (TVI, CVI, AHD), separating the various resolution options. For example, HD-TVI 4.0 identifies HD-TVI cameras up to 5MP, while HD-TVI 3.0 identifies HD-TVI cameras up to 3MP. Choose the format that is compatible with your recorder and/or LPR software.
  4. Angle, distance, and installation location. It is important to install the camera as close as possible to being perpendicular to the vehicle’s license plate. This means a head-on angle. The more off-to-the side the LPR camera is installed, the lower likelihood of getting a clear reading. If a plate is not read clearly, then it is of little to no use. The most effective horizontal angle is no more than 15-degrees. The maximum vertical angle should be no more than 30-degrees. If the camera needs to be installed higher, for example on a highway or road, it should be capturing plates at a farther distance. If capturing plates at a vehicle stopped at a gate, it’s a best practice to install the camera(s) as close as possible to vehicle license plate height (while considering environmental conditions mentioned below in numbers 8 and 9).
  5. Lighting and exposure. For the highest chance of LP readings, LPR/LPC cameras should be configured in black and white. The faster the vehicle moves, the faster the exposure. For vehicles moving up to 35 MPH, the exposure should be lowered from a default of 1/30 to 1/500. Keep in mind, when the exposure time is lowered, the less light passes through the camera’s lens, and the more infrared light is required. For LPC cameras, the amount of light passing through to the camera is so low at 1/500 exposure rate that the camera will be nearly black after the sun sets. It would be best to keep an LPC camera in night or infrared mode to achieve best captures throughout the day and night. In addition, if an LPC camera has HLC or WDR, both should be enabled. HLC or head-light compensation (also known as HLM or head-light masking) helps to block bright headlights so that a license plate can be read more easily. True WDR or wide dynamic range can help to equalize exposure of reflective surfaces, e.g. sunny asphalt, wet asphalt, etc. Do not confuse WDR with DWDR (digital WDR), as DWDR is not nearly as effective as true WDR.
  6. As of 2016, a lot of people are using starlight technology for LPC cameras because no additional infrared light is required and LPs are displayed in full color. Starlight is more ideal for vehicles traveling at lower speeds. In order to see with Starlight, the camera must have infrared mode disabled.
  7. Speed and frame rate. For moving vehicles, the frame rate of the camera should be set to 15fps (frames per second) or more. For stopped vehicles, 5fps is more than enough. The faster the vehicle speed, the higher the frame rate.
  8. Number of lanes. True LPR cameras post the tested number of lanes in the features or specifications. LPC cameras don’t post this information, as they are not designed for the purposes of capturing license plates. It would be best to test the effective range and angle on an LPC camera before deploying it.
  9. Weather conditions. Over time, there may be a need for a new front cover due to environmental damage from the sun, salt (in marine environments), or wind/water from heavy storms. To help protect against environmental maintenance issues, sun-shields are highly recommended, and you can opt for an IP67 or better water/dust-proof rating. LP readings in wet or snowy conditions will be more difficult to achieve than on clear days.
  10. Vandal-proofing. Cameras should be vandal-proof (also known as vandal-resistant, impact resistant, tamper-proof, or IK10) whenever possible, especially if installed near arm’s reach. DahuaACTi, and Uniview have various vandal-proof bullet camera options. Vandal-proof dome cameras should not be used for LPR purposes, as the curved dome cover slightly skews the image enough to result in an LP read that is not as clear as the read from a bullet camera with a flat polycarbonate lens cover.
  11. Maintenance. Over time, it’s possible that a camera with varifocal adjustable lens may need to be re-focused. It’s a good idea to use a remote focus camera (also known as motorized lens) so that you don’t have to go to the camera to re-focus it. If using a motorized lens camera with Internet access (either to the camera or DVR/NVR), you should be able to login to the camera remotely so that you wouldn’t even have to go to the site to refocus the camera. Ensure ports are forwarded to achieve proper remote access. Additionally, the camera may need cleaning from spider webs or bird nests. An ideal solution is the DotWorkz dome cleaner.

Here is a sample video of a fake LPR camera (ACTi E413) in action. This is a 5MP IP Camera with DWDR. Note that there is no true WDR or HLM, but the 10x motorized lens and vandal-proof body made it a low-cost alternative to our competition, and that is what allowed us to win the bid. Some of the LP reads are not as clean as they could be, and that is mainly due to the fact that the camera is installed to the far right of the sidewalk of this intersection. The customer was happy with the price and performance of the cameras because they can make out plates well enough in both day-time and night-time conditions.

Here is a sample video of a true LPR Camera (Messoa 3MP Dual-Lane IP Camera, model LPR030A-ORV0750 with LS101 sun-shade). Setup options are explored.

 

Here is a sample video of a true LPR Camera (Messoa 3MP Dual-Lane IP Camera, model LPR030A-ORV0750 with LS101 sun-shade). This is a sample video for daytime and night time views on initial configuration. Another video will be created once the camera has been configured properly for night-time LPR capture.

Here is a sample of a 1080p Starlight IP PTZ Camera (Dahua SD59225UN-HNI-OEM) with 25x optical zoom. Daytime mode, shows clear capture of vehicles and people and license plates across two lanes at 400+ feet away.

UPDATES AS OF 2018-Q2:

Hikvision recently introduced a true LPR camera, but it has several limitations, some of which contradict what the camera’s specifications sheet states. More information can be learned from this unbiased field-testing from IPVM. The disadvantages to using this camera are: 1) beyond 15 MPH, the accuracy of the reads starts to drop by double-digit percentages; 2) traffic should be going in the same direction in all lanes, otherwise two or more cameras would be required for accurate reads; 3) a Hikvision NVR would be required to record footage and have LPR recognition with LPR database entries. We can offer the camera for $799.95 with free shipping within the Continental USA, $64.95 for 128GB SanDisk Ultra MicroSDXC class-10 cards, and free lifetime technical support. There are two models of this camera available: one with 2.8-12mm motorized lens, and another with 8-32mm motorized lens.

Digital Watchdog (DW) recently introduced their DWC-MB44iALPR 4MP LPC camera with 5-50mm motorized zoom lens. We can offer it for $749.95, which is slightly less than the Hikvision, but consider that it has no built-in LPR option. It has double the resolution of the Hikvision and a longer telephoto zoom lens to see further away. None of our customers who have purchased this camera has reported any issues or limitations with this camera, and speeds are rated to up to 50 MPH.

UPDATES AS OF 2018-Q4:

Here is a video of the DW LPR camera in action, on the DW Spectrum IPVMS software:

Lastly, we have successfully used a Dahua OEM 4K (8MP) H.265 Starlight bullet camera with 2.8-12mm motorized zoom lens for LPC and an IP67-rated housing to withstand harsh environmental conditions. Starlight mode allows the camera to see the colors of vehicles at night time, as long as there is sufficient ambient lighting. The 8MP resolution makes it ideal to view plates across 3 lanes of traffic in crisp detail, but the 12mm lens limitation is not ideal for viewing farther distances as are the other Hikvision or DW LPR/LPC cameras. The price point on this one is between $379-$399 depending on quantity desired. And for a limited time, we are offering a free upgrade to the ePoE (extended PoE) version of this camera. Here is a video of this camera in action when properly configured for nighttime and daytime settings at another HOA in Southern California:

If you would like assistance in calculating ideal megapixels and focal length for your LPR application, or if you have a video surveillance project to discuss, please contact Custom Video Security DBA Custom Video Security at 1-310-370-9500 or toll-free at 1-877-DEALS-79 (1-877-332-5779) x1 for Sales. You may also chat with a security professional on our website during business hours at http://customvideosecurity.com, or email us at [email protected].

We can setup LPR/LPC remotely over the Internet for a fee of $450 or less per camera, depending on project complexity. In order for us to do this, we would require the camera to be online, ports to be forwarded if connecting to it directly, and the login for the camera. The horizontal angle of incidence should be within 20-degrees ideally, or up to 30-degrees maximum, with a vertical angle of 20 to 30-degrees. There should be sufficient lighting where license plates are to be captured.

By Raymond Shadman

Direct/SMS/Fax: 310-370-9500 x1

Phone:           1.877.DEALS.79 or 1.310.370.9500 x101

Email:            [email protected]

Web:             http://customvideosecurity.com

Skype:           rshadman

Raymond Shadman2017-08-22