hd lpr system for toll gate - hikvision vietnam toll gate.pdf · hd lpr system for toll gate 3...

HD LPR System For Toll Gate

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HD LPR System for Toll Gate

Hangzhou Hikvision Digital Technology Co., Ltd.

2015.9


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Content

Chapter 1 System Overview ........................................................................................... 3

1.1 Application background .................................................................................... 3

1.2 Demand analysis ............................................................................................... 3

1.2.1 Business analysis ........................................................................... 3

1.2.2 Functional requirements analysis ................................................... 4

1.3 Building Goals .................................................................................................. 4

Chapter 2 System overall design..................................................................................... 5

2.1 System overall structure .................................................................................... 5

2.2 Front end subsystem ......................................................................................... 5

2.2.1 Car-checking unit ........................................................................... 6

2.2.2 HD image acquisition and processing unit .................................... 6

2.2.3 Communication unit....................................................................... 6

2.3 Model Selection ................................................................................................ 7

2.3.1 Car plate recognition and capture unit (PRCU-4101-T） ............. 7

2.3.2 Compensating light ........................................................................ 7

Chapter 3 System installation ......................................................................................... 8

Chapter 4 Functions ...................................................................................................... 10

4.1 Main functions ................................................................................................ 10

4.2 Charging function ........................................................................................... 10

4.2.1 Prevention of cards exchanging ................................................... 10

4.2.2 Vehicle model classification assistance........................................ 12

4.2.3 Toll free vehicle management ...................................................... 13

4.2.4 Blacklist management .................................................................. 13

Chapter5 Performance Index ........................................................................................ 13

Chapter 6 System Features............................................................................................ 15

Chapter 7 Capture Performance .................................................................................... 16


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Chapter 1 System Overview

1.1 Application background

As the economy soars all these years, highway is developing rapidly. With the

increasing of road networks and tolls, many problems emerge in current highway

charging system. These problems are summarized as follows:

1) Car plate number must be entered manually which involves large

workload and thus greatly decreasing passing efficiency.

2) Cars of opposite directions exchange passing card during the journey so

fewer miles will be counted by system, which leads to large toll loss.

3) Toll collector relegates vehicle types deliberately so as to cheat the

charging system and get illegal income. They even buy and sell passing

card illegally.

4) Poor management on charge-free cars and black-listed cars.

5) Isolation between surveillance system and charging system.

It is a waste of money to build two separate systems for surveillance

system and charging system respectively.

1.2 Demand analysis

1.2.1 Business analysis

1) Improve the service quality of toll gate

By capturing plate number automatically, HD car plate recognition system

greatly reduces manual workload. That also helps to lessen the passing time

and enlarge traffic capacity of toll gate.

2) Prevent toll loss

To prevent the toll loss caused by exchanging passing card, the HD car plate

recognition system must be with following functions. The system can


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automatically recognize the car plate, and then extract binary image and write

it into passing card. At the exit toll gate, car plate will be recognized a second

time. System then compares these two pieces of information. Alarm will be

triggered if they are mismatched.

By correlating the car types and image, there is no way for toll collector to

relegate car type for extra illegal income.

3) Surveillance demands for Charging channels of toll gate

To prevent dispute, HD car plate recognition system should also be with

video recording function to keep a log of passing cars for future

investigation.

4) Resource integration needs

Charging system and operating system are both in need of video surveillance

resource. Given the two systems must be physically independent, cameras

used in HD car plate recognition system must be with two independent

network interfaces which provide those two systems with separated video

signals thereby saving cost and protecting network security.

1.2.2 Functional requirements analysis

1) Vehicle-capturing needs

The current needs require that HD car plate recognition system should

capture the passing car automatically and record its image.

2) Car plate recognition needs

HD car plate recognition system must be capable to recognize the

information on the plate such as letter, number and color. Binary image of

car plate is also required.

1.3 Building Goals

Install HD car plate recognition system to highway toll gate so that car plate can


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be captured and recognized automatically. In that way, the operating efficiency of toll

gate is greatly improved especially in terms of more standardized management,

abundant analyzed data brought by system, elimination of cheating behaviors. The

benefit it brings is obvious both in economic and social aspects.

Chapter 2 System overall design

2.1 System overall structure

HD car plate recognition system includes: front ends subsystem, transmission

system and central subsystem which implements the central management to

information collection, transmission and application.

System structure

The main system involves charging system and video surveillance system,

captured data and video stream are transmitted to those two via two physically

separated network interfaces on each capture unit.

2.2 Front end subsystem

Front end subsystem includes car-checking unit, HD image processing unit and

communication unit.


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2.2.1 Car-checking unit

Currently in our country and abroad, the most of road monitoring systems are

mainly based on two working modes: induction coil and video detection。

1. induction coil

Induction coil is the most favorable car-checking method with high precision.

Car-checking unit communicates with HD capture camera through IO control cable.

When a car passes above the induction coil, car-checking unit gets the trigger signal

and control the HD camera to capture image.

2. video detection

Car-checking algorithm is embedded in the capture camera, so it is no need to

underlay the induction coil. It is a good alternative of induction coil which features

long construction period, damage of road and large maintenance workload. But still

its capture rate is lower than induction coil. This shortcoming could be made up

through multi-frame checking method.

2.2.2 HD image acquisition and processing unit

This unit consists of capture unit, fill-flash unit and column unit. Specifically

camera used in capture unit is 3maga pixels and fill flash unit adopts strobe LED

lamp.

Progressive scanning CCD of industrial level and high-speed DSP are integrated

in HD capture camera. Each unit can complete functions such as image capturing, car

plate recognition independently thus enhancing the processing ability of the whole

system. In that way, the system becomes more simple and easy to extend.

2.2.3 Communication unit

Composed by Ethernet switches and transmission link, this unit is mainly

responsible for data transmission and exchanging


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2.3 Model Selection

2.3.1 Car plate recognition and capture unit (PRCU-4101-T）

1/1.8 inch 300maga pixels high definition color camera

2048（H）×1536（V）；

Support car plate recognition；

Support LED light compensation；

2.3.2 Compensating light

2.3.2.1 White-light LED compensating lamp （SLU-2100）

16 LED lamps；


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Color temperature：5000-7000K；

Trigger frequency：50Hz~400 Hz；

Response time：≤20us。

Chapter 3 System installation

The following picture shows the typical application of HD Car Plate Recognition

System used in highway toll gate. Equipped with HD plate recognition cameras of 3

mega pixels, the capture unit is mounted on toll island.

On-site mounting

The following picture shows the on-site effect：


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On-site effect

Induction loop is under laid 300mm beside the toll window and the exact

dimensions are as below.

100mm

100mm

2200mm 2400mm

800mm100mm 100mm

1000mm

Dimensions of induction loop


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Chapter 4 Functions

4.1 Main functions

Main functions of HD Car Plate Recognition System include: image capturing,

car plate recognition and video surveillance.

1) Capture and recognition function

This system can capture image of automobiles automatically and recognize

plate number.

Plus: oversea version must be customized according to different areas

2) Data provider function

This system can provide key information of cars to charging system such as

binary plate image and HD car image of frontal view.

3) HD surveillance video stream

4) Capture units provide HD video stream to charging system and surveillance

system.

5) Support Countries and regions: Singapore, Malaysia, Indonesia, Australia,

Korea, Vietnam, Thailand, Hong Kong, Macao, Taiwan, Philippines, Turkey，

United Arab Emirates

4.2 Charging function

4.2.1 Prevention of cards exchanging

1) Implementation principles

For Enclosed highway, drivers get passing card at the entrance and hand in it at

the exit together with passing fee. At entrance, capture cameras read in car plate

number and write its binary image into the passing card. When the car gets to the exit,

the system compares these two pictures. An alarm will be triggered asking for manual

intervention if any differences are found.

2) Processing flow


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Entrance flow Exit flow

There is no charging process at Highway Entrance. Camera in lane controller

reads in plate number, converts it to binary image and writes it into IC card (the same

thing as passing card in preceding paragraph) ,

Drivers carry that card all the way to the exit. After charging process, processing

data(car plate recognizing result, entrance number, vehicle model, processing type,

lane number, toll collector number, passing time ) produced by lane controller will be

saved locally and also uploaded to charging system at the same time.

At the exit, lane controller will compare the plate number with which saved in IC

card. If they are mismatched, the system will invoke the original plate images

captured at entrance and exit respectively and compare them again. If the result is

negative then the plate binary image captured at entrance will be displayed on the

screen of lane controller and also an alarm will be triggered.

In actual implementation, recognition rate cannot get to 100%.In some cases, car


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plate cannot be recognized successfully. To make up that deficiency, binary image

comparison technique is adopted in this system. By using that, stained plate

recognition problem is solved. Data size of binary image is very low and can be easily

saved into IC card. Moreover, internet is not necessary for Data transmission between

entrance and exit so system requirements are not high and data transmission is much

safer, faster and more reliable.

3) Comparison algorithm of binary image of plate

Image comparison is a relatively complex problem. This system mainly adopts

techniques such as revolving correction, sliding matching and elastic matching to

judge two pictures if they are from the same origin.

The matching module is packaged into a dynamic link library, so the lane

controller only needs to invoke interface functions to complete matching process.

In the situation when no reliable plate recognition result is available, this

algorithm perfectly extracts the plate number from binary image. By taking full use of

reflecting light, recognition result can be guaranteed even in some special

circumstances where car plate is seriously stained.

4.2.2 Vehicle model classification assistance

1) Implementation method

First is to set up a library including plate numbers and vehicle models, each

number correspond to a vehicle model. Then when toll collector enters the vehicle

model, the data including plate number will be uploaded into sever and compared in

the library.

2) Processing procedure

Establishing data library automatically

When a car first passes through the toll gate, its relative information such as plate

number and vehicle model will be sent to data server. Among them, plate number is

recognized by lane controller while vehicle model is entered by toll collector


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manually.

Alarming automatically

When the same car passes toll gate again, system will compare the plate number

and model automatically with the record in the library. If they are mismatched, the

system will trigger the alarm to remind auditor.

Audit

Auditor confirms the vehicle model through the car image and record. Then the

correct data will be updated into the library.

4.2.3 Toll free vehicle management

Establishing a database for toll free library and only the vehicles in library can

pass for free.

4.2.4 Blacklist management

Establish a data base for blacklisted vehicles. When the vehicles in the blacklist

pass, alarm will be triggered asking for further handling

Chapter5 Performance Index

Serial

Number

Project Index

1 Capture and recognizing time ≤200ms

2 Plate recognizing rate Customization for different areas

3 Captured image index Definition 2048（H）×1536（V），JPEG，about400KB

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Binary plate image index

Dimensions （length × width）: 112×20pixels（depends

on particular case）

size：≤280byte（depends on particular case）

5 Mean Time Between Failures

MTBF ≥20000h


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Serial

Number

Project Index

6 Shutter speed 1/25s to 1/100,000s ，support continuous adjustment

7 Trigger mode Support on-off external input mode and software

instruction trigger mode.

8 Interface two 10/100/1000Mbps Ethernet interfaces，one RS485

interface ，one RS232 serial port。

9 Column dimensions Height 1300，chassis R150（depends on particular case）

10 IP Grade HD plate recognizer：≥IP55(Compensation LED :IP65)

11 Power source 100VAC~240VAC，48Hz～52Hz

12 Power consumption ＜50W

13 Operating temperature -10℃～+60℃（without heater and radiator）

14 Operating humidity ＜95%@40℃，No condensation


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Chapter 6 System Features

1. Intelligent HD cameras integrated with image capture and recognizing

Intelligent HD cameras adopt HD CCD, ISP and high-performance

DSP architecture. It supports JPEG and H.264 video stream output

simultaneously. More importantly, image capture and plate recognition

are both completed in HD cameras. So the system is very simple and

easy to extend.

2. Dual network interfaces and output ports

The two network cards are physically isolated so that data security can

be guaranteed. DSP in the camera generates two copies of original data

and sends them to corresponding network cards whereby the data is then

uploaded to charging network and surveillance network respectively. It is

a very cost-efficient design.

3. High plate recognition rate

The plate recognition technique includes plate locating and character

segmentation and it is in leading level in so many domestic industrial

applications. We also have total property right of his technique.

4. Advanced matching algorithm

In the case where the plate is seriously stained and no clear image can be

acquired, system callouts the original plate image (captured at the

entrance) saved in IC card and compares it to the image captured at exit.

The matching module adopts advanced image matching algorithm which

is able to judge if two images come from the same origin. The

automatically matching algorithm greatly relieves manual workload and

promotes the plate matching rate.


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Chapter 7 Capture Performance

Daytime Performance

Nighttime Performance

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