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TRIAL OF NEW GENERATION AUTOMATIC NUMBER PLATE RECOGNITION

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					TRIAL OF NEW GENERATION AUTOMATIC NUMBER
      PLATE RECOGNITION TECHNOLOGY


                July 2009
                National Motor Vehicle Theft Reduction Council
Trial of New Generation Automatic Number Plate Recognition
                                               Technology
                                     ISBN 978 1 876704 98 8
                         REPORT OUTLINE

Date:             July 2009
ISBN:             978 1 876704 98 8
TITLE:            Trial of New Generation Automatic Number Plate
                  Recognition Technology
ADDRESS:          National Motor Vehicle Theft Reduction Council
                  Suite 1, 50-52 Howard Street
                  NORTH MELBOURNE VIC 3051
                  E-mail:       info@carsafe.com.au
Type of report:   Evaluation Working Paper
Objectives:       To provide an in-field assessment of a low cost, high-
                  performance automatic number plate recognition system
                  developed by SenSen Networks in a vehicle crime
                  environment.
Program:          Enforcement (Improving Local Police Responses)
Key Milestones:   Completed
Abstract:         In 2007 the NMVTRC formed a strategic partnership with
                  technology developer SenSen Networks to trial a new
                  low-cost Automatic Number Plate Recognition (ANPR)
                  system in a vehicle crime reduction setting with the co-
                  operation of Victoria Police.
                  The field trials confirmed the technical proficiency of the
                  SenSen system indicating very high levels of read
                  accuracy compared to the currently most commonly
                  deployed system and fewer false alarms against vehicles
                  of interest data.
                  By using off-the-shelf cameras, the SenSen system
                  represents a significant financial saving over current
                  industry offerings.
Purpose:          Encouraging an improved strategic police response to
                  vehicle crime in local areas is a core objective of the
                  NMVTRC’s work program.

Key words:        Automatic Number Plate Recognition, ANPR, police
                  responses, vehicle crime.
                               DISCLAIMER
The observations contained in this report are provided in good faith and solely
in the interests of promoting innovative responses to detecting and deterring
vehicle crime. The NMVTRC acknowledges that the design of its trial has
some limitations. Readers should take this into account in their assessment
of its findings.
                                FOREWORD
Encouraging an improved strategic police response to vehicle crime in local
areas is recognised as an important part of the NMVTRC’s work program.

Automated Number Plate Recognition (ANPR) systems use a camera and
optical character recognition software to capture an image of a vehicle, locate
the number plate within the image and convert the number plate to a string of
text and numerals. The text may then be compared with databases
containing vehicles of interest to enforcement agencies to generate
appropriate alerts for on-road interdiction or point-in-time tracking.

In 2007 the NMVTRC formed a strategic partnership with technology
developer SenSen Networks to trial a new low-cost Automatic Number Plate
Recognition (ANPR) system in a vehicle crime reduction setting with the co-
operation of police in New South Wales and Victoria.

The principal claimed benefits of the SenSen system over existing
technologies was that it would be much lower in cost and provide more
operational flexibility.

The total cost of the SenSen MANPR system is designed to deliver highest
accuracies at one-third of the cost of the currently most commonly deployed
ANPR systems—with the capacity to simultaneously detect cars up to 3
adjoining lanes.

The field trials confirmed the technical proficiency of the SenSen system
indicating very high levels of read accuracy compared to the currently most
commonly deployed system and fewer false alarms against vehicles of
interest data.

While the wider deployment of a nationally or regionally networked ANPR
capability for Australia will be determined by national and state/territory
governments, the SenSen trial demonstrates the undeniable value of a low-
cost, high-performance system to detecting criminal activity involving the use
of a motor vehicle, including vehicle theft.
BACKGROUND
Forms of ANPR technology have been used in Australia since the mid-1990s.
The first significant example was Safe-T-Cam developed for the New South
Wales (NSW) Roads and Traffic Authority (RTA) by the CSIRO. The system
was designed as a heavy vehicle compliance tool—checking speed (including
average speed between camera locations), driving hours and route access
control. Based on video optical character recognition the system now has an
extensive network of cameras in NSW and South Australia. However, it is
dependent upon expensive camera hardware and site protection (against
malicious damage) and is subject to high error rates in certain environmental
conditions.
More recently tolling systems, which use video capture as a back up to
electronic tag detection, have become increasingly common as part of new
road developments in eastern Australia. However, they too are prone to
relatively high error rates due to the duplication of number plate character sets
between jurisdictions and their inability to successfully read the state/territory
identifier.
Finally, fixed and mobile ANPR technology is increasingly being used by
police and transport agencies to detect unregistered and other vehicles of
interest but have again been limited in their application by their generally
narrow field of view and other practical considerations. Police in NSW have
deployed an extensive network of cameras across Sydney for anti-terrorist
purposes.
In late 2006 the NMVTRC was approached by SenSen Networks—a
commercialisation venture originally based at the University of Technology
Sydney in relation to a new system it had developed.
SenSen indicated it was looking for new ‘application spaces’ in which to refine
its system which utilised off-the-shelf analogue/internet protocol cameras and
processor hardware supported by sophisticated probability and statistical
inference based software—dubbed by UTS as Data Fusion. SenSen claimed
the principal benefits of its system over existing technology was that it offered
greater operational flexibility in—
 using off-the-shelf CCTV cameras that function effectively under ambient
    street lighting with or without the need for infra-red lighting and special
    optics; and
 managing character image aspect ratios (which means that the plate will
    be detected anywhere in the camera’s field of view rather than having to
    track through a narrow ‘channel’ in order to be detected).
This report provides a high level introduction to SenSen Networks’ ANPR
System including its capabilities, advantages and limitations.
As part of the NMVTRC trial the system was subject to extensive in-field
testing via collaboration between the NMVTRC and Victoria Police1.


1
 A Memorandum of Understanding between the NMVTRC and Victoria Police set out the terms and
conditions of the collaboration. The NMVTRC maintained sole responsibility for the contracting and
payment of any fees for services provided by SenSen. Victoria Police contributed by assigning
While the SenSen system can be deployed for a number of applications, this
report highlights the key features in the context of a Mobile ANPR application
(MANPR)—purpose built by SenSen in response to expert feedback from
experienced field officers from Victoria Police’s (VicPol) Region 3 Vehicle
Theft Task Force based in Melbourne’s outer north-west.

THE SENSEN SYSTEM
SenSen was to develop a portable, camera-independent and easy to deploy
MANPR system that would—
 operate from a stationary or moving vehicle using low cost off-the-shelf
  cameras; and
 detect and generate alerts for stolen, unregistered and other vehicles of
  interest, in real-time.
The system is designed to be used with any standard, low cost, off-the-shelf
cameras and can support up to two concurrent cameras on board a stationary
or mobile vehicle.
The SenSen System employs patented image analysis techniques combined
with temporal data fusion, to provide a usable image with standard off-the-
shelf cameras.      As no infrared (IR) light sources are required for plate
illumination, SenSen is able to provide a sound technological solution at a
fraction of the price of the current ‘gold standard’ alternatives. The non-
reliance on IR also enhances its use in covert applications.
The key innovations and technical differences from alternative conventional
products are summarised in the following table:

              SenSen MNAPR System                           Conventional ANPR System

 1   Uses Patented, Temporal Data Fusion;            Uses a single image frame in which the
     fuses information from all image frames in      vehicle is visible.
     which vehicles are visible.

 2   Enables highly accurate readings out of         Needs crisp, non-noisy data where
     noisy data from low cost, low resolution        nothing other than the license plate is
     cameras.                                        visible.

 3   Enables Off-the-Shelf Cameras to Provide        Needs specialist, custom built automated
     High Levels of Intelligence.                    cameras that are both expensive and
                                                     difficult to use.

 4   Can deal with much higher levels of             Can only deal with well specified,
     rotation and skew in plate images.              predefined angles and skew.

 5   Intelligence is in the software with            Intelligence is in the Camera hardware
     flexibility to work with any camera.            with tightly coupled, relatively simple
                                                     software.




experienced personnel to field test the system in a variety of settings and providing feedback to the
NMVTRC and SenSen on how the system could be optimised for efficient operational performance.
The total cost of the SenSen MANPR system is designed to deliver highest
accuracies at one-third of the cost of the currently most commonly deployed
ANPR systems—with the capacity to simultaneously detect cars up to 3
adjoining lanes.
The SenSen system comes with simple plug and play features. An operator
needs to know about only the hardware buttons/connectors and GUI
(graphical user interface) features to operate the system. It comprises the
following hardware and software components—

1. Hardware
       Camera - Off the shelf (e.g., Sony Handy Cam) or Infra-red
       A purpose built Computer with a DSP PCI card
       10” Mini Monitor with Touch screen features
       Car Battery (in addition to the main car battery)
       Accessories such as mounts, adaptors & cables

2. Software
       Redhat Fedora 7; Linux Operating System
       SenSen MANPR Core Engine
       Java based Front end GUI
       PostgreSQL Database

The hardware components may be pre-installed in the vehicle except for the
camera. The user only needs to configure the camera according to his or her
requirements. The software is also pre-installed. Complete details on how to
operate the software are provided in the user manual. The MANPR software
developed by SenSen is easy to install and highly responsive. The GUI
provides user-friendly features which are very easy to operate and navigate
through. Sufficient care has been taken in building the GUI features based on
constant inputs from VICPOL and any additional features can be provided
with quick turnaround.




                      Figure 1: SenSen MANPR GUI
The control options can be used to easily configure the SenSen MANPR
system. The 'Vehicle of Interest' or 'Alert' data can be efficiently uploaded in
the system. For example, a typical data comprising of 300,000 records could
be easily uploaded in less than 3 minutes by means of a simple USB. This
data is used for matching the License Plate Characters. The resultant alert
data generated by SenSen MANPR is stored in the local data base. The
search and drill-down feature is provided to access the stored vehicle and
alert data.

The Export feature in the GUI is provided to export or upload the 'detected
alert data' in CSV & PDF format. It can be customized to any other desired
format (such as CSV) to a storage device or can even be sent through an e-
mail (provided the system has access to the internet).




             Figure 2: Exporting an Alert Report from the GUI

The SenSen MANPR System uses real time video processing to detect the
intelligent information from the video frames. Other system features include—
    1. Secure login
    2. Remote operation meaning that the system can be left unmanned and
        the intelligence gathered in a session can be viewed, stored and
        transmitted over the internet from anywhere in the world.
    3. Real-time alerts of 'Vehicle of Interest'.
    4. Hardware and connectors suited to withstand the typical outdoor
        environment and in-car conditions.
    5. Low power consumption.
    6. Fast processing capability that can detect registration plates of vehicles
        travelling at up to 200km/h.
The Software has been rigorously tested for 24/7 availability. At this time,
there are no known system crashes, software memory leaks or any other
failure issues.
The SenSen MANPR system can be easily deployed at any location or simply
moved on to any other vehicle in minutes. As the system is built with off-the
shelf computers, cameras and accessories ongoing management and
maintenance costs are expected to be low.

SYSTEM ACCURACY
In field tests with Victoria Police the system proved to be highly accurate.
The following comparative results are drawn from extensive testing and
measurement carried out by experienced Victoria Police personnel using
knowledge gained from the use of a number of commercially available
alternative systems in a variety of lighting conditions and operating
environments, including major arterial roads, freeways and car parks. They
compare the performance of the SenSen system using a Sony Handy Cam
with an industry standard IR camera.

Category       Feature                                             Accuracy/False Alarms


                                                                   Sony            REG IR
                                                                   Handy Cam       Camera
Basic          License Plate characters displayed as ‘Last         95%             92%
Accuracy       Cars’ in the MANPR Graphical User Interface         Provides        Provides
               (GUI) – This is the best possible result obtained   much wider      a very
               by data fusion of multiple image frames             field of view   narrow
               captured by the camera. It is one of the three                      field of
               ranks of results available to the user.                             view
Accuracy       As there are two more lower ranked results          98%             95%
For Search     available in the database which can be queried
Application*   at any time, there is a high chance of finding
               cars of interest when queried.

False Alarms   Due to occasional misreads of MANPR system,         2%              4%
               there is a chance to get an alert that matches a
               misread leading to false alarms.

				
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