License Plate Recognition - A Tutorial

August 2005

This brief provides a short introduction to Internet Protocol (IP) surveillance systems that

use digital cameras networked via standard Ethernet networks. The brief explains basic

technology concepts, provides a benefit overview, describes advantages for specific

security applications in selected vertical markets, and details the necessary requirements

and considerations for implementation of the technology.

D-Link Systems, Inc.

August 2005

The growth in IP Surveillance systems is quickly gaining significant ground on

conventional analog closed circuit television (CCTV) security camera installations for

reasons of both performance and cost-benefits.

IP Surveillance systems digitize video streams at each camera on the network, this digital

stream is then transferred over a standard wired or wireless Internet Protocol (IP)

network. Unlike traditional analog closed circuit television systems that transport analog

signals back to a centralized video recording device, IP surveillance systems digitize and

compress the video at each camera and send a digital signal across a common IP or

Ethernet network. IP Surveillance employs a decentralized data encoding system that

sends binary data across a shared, standards-based IP network – the same one used for

email, Web pages, file transfers, and other data network applications.

Since digital networked surveillance is IP-based, users can monitor, store, and archive

video, audio and associated application data over the Internet or across private data

networks. Compressed video can be carried anywhere that the IP network extends as

opposed to CCTV systems that are built on and require dedicated coaxial cabling.

Anyone with the proper access credentials and a standard browser can monitor video as

well as control and configure the camera from any location that has Internet or private

network connectivity.

Since networking equipment and IP protocols adhere to open standards, the IP

Surveillance system itself is low cost, and new integration opportunities and applications

are continually coming into focus. Event-driven alert and alarm software for IP systems

already far exceed the capabilities of old CCTV systems. Digital IP cameras can be used

to monitor on a 24x7 basis and be configured to trigger on events while immediately

alerting administrators when certain conditions arise or specific thresholds are reached.

A growing number of security organizations, small and medium sized businesses, and

home users throughout the world use networked IP Surveillance equipment, and industry

analysts expect that number to rise dramatically as organizations of all sizes continue to

understand the benefits of the technology. The advantages that IP Surveillance has over

traditional analog systems are numerous, and the benefits usually fall into one of the four

following categories:

When compared to analog CCTV systems, networked IP camera systems have several

cost advantages. First, the wiring required is less expensive. Most buildings contain

installed Cat-5 data networking cable, and if additional wiring is necessary, Cat-5

costs less per foot than single purpose analog coaxial cable. Thus, IP Surveillance can

often use the existing wired infrastructure and not require the installation of a second

and parallel cabling infrastructure.

A digital, packet-switched network enables centralized, cost-effective management.

IP networks carry all kinds of data, including video, audio and standard document

files like email and web pages. Any existing infrastructure and personnel used to

manage the data network can easily absorb a new IP Surveillance application.

Infrastructure maintenance, monitoring and management of IP Surveillance

applications are easily learned without the need for specialized components, cabling,

or training required for a separate analog CCTV alternative. The elimination of a

separately installed and managed infrastructure will save time and resources.

Since IP networks employ well documented, understood, and heavily deployed

standards for cabling and transmission protocols, the costs for equipment and service

have diminished as application adoption increases. Technology advancements and

adoption have already had a profound effect on the price of networking equipment

and digital cameras. Expect that trend to continue as competition naturally flourishes

in a standards-based deployment environment.

Event Driven Intelligence

as smart as the person monitoring it at the moment it is being monitored. With IP

networks there is access to a wide range of automated software settings and alert

systems that make security management more efficient, less costly, more intelligent

and less error prone.

IP systems handle motion detection, event triggers, and alert automation and have a

multitude of options for changing frame rates, resolution and timed record cycles.

For example, certain cameras might only send data to the recording servers when a

specific threshold of motion is detected. Sensitivity settings can be adjusted so

insignificant movements will not trigger a recording. This saves recording space and

human analysis time by keeping only what is relevant to the particular security

situation at hand. With digital images, integration is possible with available third

party applications for license plate recognition, people counting, Geographic

Information Systems (GIS), and face recognition.

Alerts can also be configured and emailed to any email address or group and retrieved

with any IP-connected communication system containing an email client. This

includes notifications to handheld PDAs, cell phones, or other IP connected devices.

With an analog camera system, none of these applications can be performed without

some digital conversion. The multiple analog/digital conversions required, however,

reduces image quality. With IP Surveillance systems, the digitization process occurs

once at the camera and is carried across the digital IP network. The video data starts

digital and stays digital throughout the infrastructure.

Superior Image Quality

Network IP Surveillance equipment also provides better image quality than analog

systems. Analog coax cables can compromise image clarity, since signals can degrade

over long cabling distances. Analog cameras adhere to NTSC/PAL standards,

effectively limiting resolution to 0.4 megapixels.

Network cameras, on the other hand, use progressive scan technology and high

resolutions that depict moving objects more clearly and cover larger areas with

sharper images. These technological advantages enable digital pan, tilt and zoom

features that analog systems can only perform with additional, dedicated cabling.

Securing the Security Camera

IP Surveillance systems can encrypt data across the network, so only the cameras and

servers know what kind of packets to expect across the system. Without the proper

authentication keys, outsiders cannot break into the network to steal video data or

feed false video into the system.

With analog systems, access is needed to the cabling to tap into the electrical circuit.

Video can be fed into the wire or recorded off of it at will without raising any

intrusion alarms. The analog system sees electricity coming across the wires. IP

systems are much more difficult to compromise because encryption requires two

nodes that agree on exactly what is being sent and received (and have the algorithms

or keys that decode the data). Any interruption to the data stream can automatically

trigger alarms and alerts.

One-Way or Two-Way Audio

Since IP Surveillance systems are merely passing around information packets, any

kind of additional data (sound, graphics, applications, event triggers, etc) can

accompany the data stream. Thus, one-way or two-way audio requires only

microphones and speakers at the end points when used with appropriate IP cameras

that support audio capabilities. Analog systems, on the other hand, can’t handle single

channel audio or two-way sound channels without added cabling and expense.

Deploying audio with the video images becomes very simple in IP Surveillance

applications.

Back-Up and Storage

Storage systems are easier to configure and more reliable with IP systems as well. All

the redundant components found in standard computer based systems like RAID

disks, uninterruptible power supplies and secure off-site storage can be leveraged in

IP Surveillance applications. In many cases, the infrastructure may already exist and

available staff will not have to learn new storage systems. Analog systems, however,

require proprietary recording and back-up systems that add significant component,

maintenance, and training costs as the system grows. In addition analog tape based

recording systems require ongoing replacement tapes. After a period of use the tapes

become stretched, can no longer be effectively used, and must be replaced.

Standards Based

The Internet Protocol itself offers a wide range of flexibility because it is a global

standard that runs on a wide range of open, standardized, low-cost equipment. “Best

of breed” products and services can be combined from an assortment of vendors.

Price competition and vendor choices truly make it a buyer’s market.

Of course, IP Surveillance data can be securely viewed anytime, anywhere from a

standard Web browser like Internet Explorer. This simply cannot be done with analog

systems that are relegated to the local redundant cabling infrastructure that has been

established. Remote site monitoring becomes difficult with analog CCTV systems.

PoE and 802.11 Wireless LAN

There are a couple of other features or standards that make IP Surveillance even more

attractive: Power over Ethernet (PoE) and 802.11 wireless LAN connectivity.

With external PoE adapters, power is delivered to the IP Surveillance cameras via

Cat-5 Ethernet cabling. This eliminates the need for costly electrical wiring and opens

up more opportunities for effective camera placement. Equipment can be placed

based on the needs of the application versus where power outlets may be available.

More effective camera placement will lend itself to a more effective surveillance

system. PoE enables flexible, more efficient network designs, simplifies and speeds

installation, and generally reduces costs across the board. PoE also facilitates

changing environments or temporary deployments.

PoE technology allows for centralized power management. With centralized power

management, the IP network is protected by uninterruptible power supplies with

battery back-up (UPS). If power goes down, the critical network and surveillance

infrastructure can stay online. Centrally managed power enables remote shutdown or

remote reset capabilities, saving the time and expense of dispatching a technician to a

camera location. With analog CCTV systems all distributed devices need UPS power

supplies adding complexity and costs to the overall system.

Wireless installations offer similar kinds of benefits. If running Ethernet cable is

undesirable, installing low cost 802.11 wireless access points and placing wireless

cameras anywhere within the cell of coverage is an option. The 54 Mbps 802.11g

standard is sufficient for many video surveillance applications. Current wireless

security standards, like WiFi Protected Access (WPA) offer robust authentication and

encryption for the wireless signal to prevent snooping and interception of the video

signal.

IP Surveillance applications are also highly scalable. Cameras can be added one at a

time, whereas DVR analog systems may require increments of 8, 16 or 24 additional

cameras. As a company grows, the digital system keeps costs in check.

With Gigabit and 10 Gigabit Ethernet readily available, the IP network is scalable as

well. Several cameras can be supported on the same IP infrastructure. Typical

switches and routers available today simply segregate traffic for larger scale video

applications. With proper network design, installations with 200-300 cameras are

common, and some organizations are easily using more than 1000 cameras at a time.

Storage and server systems scale easily and cheaply, with no need for specialized

recording equipment or training. The IP protocol is familiar to network

administrators therefore they have the knowledge needed to deploy IP Surveillance

applications.

IP Surveillance solutions cover a wide range of possible applications, including

security/safety, observation, and quality control monitoring. A typical example is remote

building surveillance where the interior or exterior of a building may be monitored safely

from a second secure building.

Examples of and requirements for IP Surveillance solutions can be identified across a

wide mix of vertical industries. All types of organizations, from government agencies

and educational institutions to research labs and retailers, can benefit from IP

Surveillance systems. Consider some of these possible uses:

installation protection (military, energy, infrastructure), and transportation security

measures require continuous, intelligent surveillance in large scales.

theft, and vandalism.

internal and external theft as well as from other criminal activity. Retailers want to

provide a safe environment for their patrons while also protecting themselves.

airports.

A wide variety of businesses, research organizations and manufacturing facilities require

monitoring for productivity measures, workplace safety, and the protection of intellectual

property, logistics systems, and warehouse supply chain systems.

Several considerations come into play when implementing an IP Surveillance system.

The following points or options should be considered when implementing an IP

Surveillance application.

A number of network variables dictate optimal network speeds, storage capacity and

server performance. Ideally, the network switches and routers should provide high

performance and offer a range of speeds from 100 Mbps to 10 Gbps. For high quality

feeds or large numbers of cameras, consider 100 Mbps attached cameras with backbone

network speeds of 1 Gigabit or higher. 10/100 Mbps networks can be used for

applications where high-resolution video quality is not as critical. To avoid choppy,

delayed data transfers traffic calculations should be made with respect to network

performance. Estimates of throughput and peak demand requirements that will be placed

on the network and how those demands may impact other network applications should be

considered. Examine how much other traffic is moving around the network at specific

times of the day. Consider switching infrastructures that implement Quality of Service

(QoS) mechanisms to provide the desired level of video quality to your IP Surveillance

application.

The 802.11g wireless standard offers less throughput, but it’s perfectly fine for certain

applications. With a dedicated network of wireless cameras, capturing high-resolution

images without taxing the network is possible. Performance depends on the resolutions

and frame rates selected for each camera. Security is also an issue with wireless

networks. WPA or WEP authentication and encryption are recommended.

With PoE technology, camera placement can be made in the best locations, untethered

and independent from AC power outlets. This enables a centralized power management

strategy with UPS battery back-up availability for all cameras. The same UPS system that

delivers back-up power to servers and data center equipment backs up the cameras – it

can be managed from the same console.

Digital IP camera vendors sell a wide variety of indoor and outdoor cameras that perform

well in all kinds of environments. Enclosures with thermal barriers on certain models

protect the equipment from extreme weather. Others contain heater blowers for cold

temperature climates and waterproof seals to protect from water damage.

Camera capabilities will vary based on the application. The cameras come in video only,

audio/video and two-way audio with speaker attachments and built in microphone

options, as well. Some are stationary while other offer remote controlled pan, tilt and

zoom (both digital and optical). Another camera consideration is the lighting conditions.

Some cameras will be much better than others in low light conditions. Whereas most

cameras would provide no image at all in low light conditions, those with low light

sensitivity can still produce a picture.

Monitoring stations provide multi-camera monitoring via either a hardware or software

interface. Multiple monitors or a single screen split into multiple frames can be

configured with IP camera management software.

Recording and playback options for setting sensitivity levels, motion trigger thresholds,

and screen area triggers are available. Surveillance applications should be analyzed to

determine the requirements for these types of advanced functionality.

Management and monitoring software solutions sold with digital IP systems include

automated snapshot, event, alarm and motion detection features. Check with your vendor

to determine whether these applications are available and if they come at additional costs.

D-Link provides the management and surveillance software free with its IP cameras,

unlike some other vendors.

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I-Cube.   All rights reserved.  Revised: February 18, 2008 .