I. Taiwan Province Third-orderControl Points Reconstruction and Implementation

(1)Project Initiation:

During the Japanese Colonization Era, there were 7,903 control points to be implemented in Taiwan. Some of those control points have been lost or severely damaged due to natural disasters, changes of topography and surface features. Reconstructions are mostly handled by individual units and therefore lack integrated planning to ensure conforming precision. To integrate existing results of control surveys, the NLSC defines plans to make overall third-order control point reconstruction and new implementation in Taiwan area.

(2)Project Contents:

1.Five-year plan for control points reconstruction and implementation of control points in TaiwanProvince:

Execution time: 5 years (1995 – 1999)

Execution area: Keelung City, Taipei County, Taoyuan County, Hsinchu City & County, Miaoli County, Taichung City & County, Chiayi City, Chiayi County (western area), Tainan City & County

Quantity:1967 third-order control points

2.Follow-up plan for control points reconstruction and implementation in TaiwanProvince

Execution time: 4 years (2000 – 2003)

Execution area: Nantou County, Changhua County, Yunlin County, Chiayi County (eastern area), Kaohsiung City, Kaohsiung County, Penghu County, Pingtung County, Taitung County, Hualien County, Yilan County; and Kinmen County and Lienchiang County of Fukien Province

Quantity:about 2500 third-order control points

• Operation Flowchart

(4)Project Implementation Status:

The reconstruction and implementation of Taiwan-Fukien third-order control points uses GPS-based surveying and was completed in 2003 with 4710 points.

(5)Benefits of Project Implementation

1.Integrated planning for survey and implementation of control points enhanced conformity of survey results;

2.Reconstructed and newly implemented third-order control points have been planned with such density that facilitates future references;

3 all levels of control pointsA “control point database management system” was established to manage survey results that can be provided for all sectors’ references. The database enables resource sharing and establishing foundation for national land Geographic information system.

4.Beautificationof the control point landscape facilitates promotion of control point preservation, which achieves the plan for the permanent existence of control points.

(6)Results Statistics:

 

II.Taiwan-Fukien Area Third-order Control Points Management and Maintenance

(1)Project Initiation:

After comprehensive reconstruction and new implementation of third-order control points in Taiwan Area by 2003, a new national base control survey framework was completed. For effective management of all orders of control points, the NLSC conducted inspection and test operation on third-order control points in accordance with inspection on the first- and second- order satellite control points, level points and gravity points carried out by Ministry of the Interior. The purpose was to maintain an integrated and highly accurate national survey coordinate system.

 

(2)Project Contents:

1.To cooperate with the “National Survey and Mapping Development Plan” as promulgated by Ministry of the Interior, the NLSC has, in the period between 2004 and 2007, completed Taiwan Area third-order control points and all orders of tie measurement trigpoints during reconstruction and new implementation of third-order control points. The survey areas were based on county or city, with adjacent counties or cities combined for operation.

2.This project is to be implemented on five-year cycles, in principle, based on the inspection cycle for Taiwan Area third-order control points and all orders of trigpoints. The required expenditure will be budgeted in accordance with regulations.

3.For planning on annual inspection, the "Five-year plan for reconstruction and new implementation of control points in TaiwanProvince (1995 - 1999)" and the "Follow-up plan for reconstruction and new implementation of control points in TaiwanProvince (2000 - 2003)" should be taken into consideration for scheduling and area selection. The top priority should be given to the essential areas of Taiwan's western plains, followed by Kaohsiung-Pingtung plain and the eastern Lanyang plain, Hualien-TaitungValley, and peripheral islands. However, PenghuCounty as the peripheral island and KinmenCounty and Lienchiang County of Fukien Province are areas with less visible changes in the crust and due to limitation of funding approved, they were for the time being not included for inspection. As a result, the total number of points planned for management and maintenance was adjusted to 4537.

 

(3)Work Items:

1.Formulate operation rules for management and maintenance of control points

2.Implement inspection of third-order control points set up by the NLSC.

3.Implement inspection on all orders of tie measurement tirgpointsduring reconstruction and new implementation of third-order control points

4.Implement training on the satellite positioning survey adjustment calculation

5.Specify rules for providing control points survey results.

6.Implement setup, management and maintenance of database for control points.

7.Implement real-time reporting system for control points.

 

(4)Project Implementation Status:

Starting from 2004 and up to the end of 2007, the project had implemented 4,537 points in 21 counties and cities including Keelung City, Taipei County, Taoyuan County, Hsinchu County, Hsinchu City, Miaoli County, Taichung County, Taichung City, Nantou County, Changhua County, Yunlin County, Chiayi County, Chiayi City, Tainan County, Tainan City, Kaohsiung County, Kaohsiung City, Pingtung County, Taitung County, Yilan County and Hualien County. Implementation results are illustrated in chronological order, as follows:

 

(5)Actual Benefits

1.Maintaining an integrated, united and high-precision control point coordinate system, as a basis for national construction to facilitate the sustainable national land development.

2.Avoiding sporadic reconstruction of control points by each unit for purposes of saving costs, manpower and time to enhance national competitiveness.

3.Promoting satellite positioning survey technology, for enhancing data computation capabilities to ensure quality of survey results.

4.Building a comprehensive database of control points through web-based instant reporting mechanism, with detailed precision data of control points to be provided to all sectors for references.

III.National e-GPS Satellite Positioning Base Station Real-time Kinematic Positioning System Setup

With rapid development and flourished application of the Internet and wireless data communication transmission technology, GPS-based survey methods and results computation have evolved from post-processing to nearly real-time positioning model. GPS real-time kinematic positioning technology has the advantage of being simple and fast, with precision up to centimeters. However, due to positioning system errors, radio interference, and limit on radio communication distance, the centimeter precision is achievable only when the mobile station is within a few kilometers from the base station. To provide multi-objective positioning services and value-added applications, as well as to reduce the deployment density of base stations, the NLSC has planned on high-speed, broadband data transmission technology over the Internet. A national e-GPS satellite positioning base station real-time kinematic positioning system was built in 2007. Based on its continuous positioning data observed, an interpolation model was built for regional positioning errors, and high-precision results for positioning was achieved by using virtual base station real-time kinematic positioning technology (VBS-RTK). This system is useful for providing multi-objective positioning services and value-added applications.

 

In view of the availability of domestic high-quality broadband Internet services and mobile wireless data transmission environment, the NLSC adopted the advanced virtual base station real-time kinematic (VBS-RTK) positioning technology to construct the "National e-GPS satellite positioning base stations real-time kinematic positioning system", starting from 2004. The system was built with 76 GPS base stations around the country, each of which consecutively receives data from GPS satellite every single second, 24 hours a day. The collected data are transmitted in real time to the control and computation center located at Liming Office, Taichung where the data are automatically processed. Currently in Taiwan, Penghu, Kinmen and Matsu, any GPS satellite receiver that can receive data from at least 5 GPS satellites is able to obtain real-time kinematic positioning services at a centimeter-level precision, based on user’s requirement, in a very short period of time through GPRS technology or other wireless networking technology. This was not only a major breakthrough in satellite-based kinematic positioning technology, but had also formally announced the new era for domestic surveying and mapping to be in synch with global technology in terms of Internet-based application and mobilization.

 

Other than being the first set of real-time kinematic positioning systems with centimeter-level precision that has full national coverage, the "National e-GPS satellite positioning base stations real-time kinematic positioning system" provides another features of being location-based and being multi-functional and multi-objective, which can be directly used for surveying application like defining national survey bases and serving long-term purposes for national coordinate systems. It can also be used in support of seismic monitoring, observation of changes in the crust, and other earth science researches and application, as well as assisting relevant authority departments to accelerate the establishment of all types of basic national databases aimed to enhance national competitiveness. The system will play a critical role in an era of high demand for mobility, efficiency and value-added applications, and in the “space information” domain which has been identified as one of the three star industries in the 21st century.

 

To assess the accuracy and feasibility of applying VBS-RTK positioning technology in surveying and mapping business, the NLSC conducted, starting from April, 2005, a series of related test at central and northern part of Taiwan, with results preliminarily verified to show that VBS-RTK positioning accuracy is better than 2cm horizontally and better than 5cm vertically. The validated results enabled significant boost in productivity and efficiency of survey, management, maintenance and inspection of all orders of control points and Supplementary control points. In addition to controlling survey operation costs, the system’s multi-functional and multi-objective real-time kinematic positioning features are expected to be widely applied in daily life of the general public, disaster protection and disaster relief, navigation and surveillance, and various kinds of scientific researches. In such domains as policing, fire and disaster relief applications, the system is capable of task dispatching, disaster area surveillance, and incident management. In the construction domain, it is capable of pipeline planning, construction management, piling determination and staking-out. In community services, its quick and accurate locating capability will reduce social cost for finding lost elderly, children and certain disadvantaged person in the future. It can even provide such civil positioning services as navigation, dispatching, or other value-added applications requiring space information for decision support or dynamic monitoring in the domain of transportation, water conservancy, agriculture and forestry, economic planning and development, defense, environmental protection and coast guarding.

(1)Virtual Base Station RTK Kinematic Positioning Technology

To overcome the shortcomings of traditional RTK positioning technology, the Internet is used to set up virtual base stations, of which the real-time kinematic positioning technology can be used for solving the regional GPS base station network error model to effectively increase the operating range over the traditional single-RTK positioning, with positioning results being quickly and conveniently obtained and of high-precision and high reliability. Therefore, users of rover RTK station do not receive the actual data from a specific physical base station. Instead, they receive virtual data that have been error-corrected in their positioning. In other words, the RTK base station is a virtual base station with artificial results (of human processed data) but acts as a physical base station adjacent to the user’s rover station. Such a technology of applying network and wireless data transmission to coordinate for positioning is called Virtual Base Station Real-Time Kinematic positioning technology (VBS-RTK).

 

(2)VBS-RTK Positioning Theory:

The basic concept behind the VBS-RTK positioning technology is the use multiple GPS base stations to consecutively receive satellite data and by transmitting data via the Internet or other communication devices to a Control and Computation Center, where a database of regional correction parameters is derived from the collected data. A virtual base station near a rover station is then formulated with related data calculated. The RTK user has only to set up a satellite positioning receiver on his rover station, and send relevant positioning information, through a GSM-based wireless data communication transmission technology (GPRS) and in the standard transmission format (NMEA) that the GPS receiver defines for data output, to the Control and Computation Center, where simulated observation for the virtual base station is calculated and sent back in standard format (RTCM) of difference GPS to the rover station’s satellite positioning receiver for calculation of "ultra-short distances" RTK positioning. Now the user will have the positioning coordinates with precision up to centimeter. The steps for using VBS-RTK positioning technology to obtain real-time kinematic positioning data are described as follows:

1.Data pre-processing at base station’s regional network: including setting up base station network observation database and network adjustment for the base station.

2.Base station regional network solution: the Control and ComputationCenter compiles and compute each base station’s consecutive observation data and accurate coordinates, to build the regional area positioning error correction database.

3.Building observation data for virtual base station: Using wireless data communication transmission technology, the rover station sends its position data (normally a single-point positioning coordinates), in NMEA format defined by the GPS receiver, to the Control and Computation Center where system error is calculated by interpolation method, and the results are combined with actual observation data of the nearest base station to form a pack of VBS virtual observation data for sending back to the rover station in RTCM format.

4.Rover station coordinates calculation: the rover station receiver conducts the "ultra-short baseline" RTK positioning calculation.

(3) Advantages of VBS-RTK Positioning Technology

1.Enlarge effective region of operation and enhance precision and reliability for positioning.

2.Survey error and initialization time do not increase with distance.

3.User has no need to set up regional base station.

4.Can operate with individual machine by one person.

5.Can shorten operation time, boost productivity and reduce operation cost.

6.Allows all users to conduct real-time positioning under the same framework.

7.Can provide full quality monitoring on positioning results.

 

(4)System Planning, Establishment and Operation Schedule

1.2003 - system planning and test analysis

2.2004 - building northern Taiwan GPS base station network and building control and computation center

3.2005 - building southern Taiwan GPS base station network and establishing Northern and Southern RD Centers for applications; conducting test on network-based DGPS difference and VBS-RTK positioning result.

4.2006 – building GPS base station network on peripheral islands, and building portal-based management system

5.2007 – system integration, operation test, and standards defining (including documents)

6.Starting operation in 2008

(5)Architecture of National e-GPS Real-time Kinematic Positioning System

1.GPS base station network

The distance between GPS base stations should not exceed 50 kilometers in principle. A total of 80 base stations are to be built at various regions around the country. As of the end of December of 2007, 76 stations have been completed and connected for operation, as shown in the diagram below:

(1)2004: planned 23 base stations in northern Taiwan area (with 21 completed and connected)

(2)2005: planned 20 base stations in southern Taiwan area (with 19 completed and connected)

(3)2006-2007: planned 46 stations including those on peripheral islands and those to be densified in Taiwan area (with 36 completed and connected)

 

 

2.e-GPS Control and ComputationCenter

The e-GPS Control and ComputationCenter is built in the equipment room on the 4th floor of the cadastral data storage of the NLSC. Its main functions are as follows:
(1)Conducting continuous quality control, storage, processing and remote monitoring of GPS observation data;
(2)Conducting continuous computation based on the data to produce regional positioning error correction data;
(3)Compiling VBS virtual data;
(4) Sending, through mobile phone GSM/GPRS and RTCM Internet transmission protocol (NTRIP), VBS virtual observation data (in RTCM format) to each rover station.

e-GPS Control and ComputationCenter

3.Rover station:
The basic device for using virtual base station real-time kinematic positioning technology requires only a set of GPS receiver with RTK calculation function, controller and a PDA capable of Internet access via GSM/GPRS or other compatible mobile communications device. With this simple set, you are ready for VBS-RTK positioning calculation. There is no special limitation in terms of brands or models.

 

4.VBS-RTK positioning service area
e-GPS positioning system is at the moment under planning and construction. For smooth testing of survey positioning precision and system feasibility, the connected operating base stations in Taiwan, Penghu, Kinmen and Matsu areas are, together with the NLSC’s reconstructing and implementation plan for third-order control points and annual management and maintenance schedule, divided into 10 VBS-RTK positioning service areas and 4 DGPS positioning service areas, roughly coinciding with current administration unit (County). In Taiwan, Penghu, Kinmen and Matsu areas, real-time kinematic positioning services can be accessed as long as the region has access to GSM/GPRS or wireless Internet. For details on VBS-RTK positioning service areas and their setup, please refer to the following:

VBS-RTK positioning service area for Taiwan-Penghu-Kinmen-Matsu

 

(6) e-GPS Real-time Kinematic Positioning System Exhibition
To comply with the international trend of satellite positioning surveying and mapping technology being Internet-based, mobile, multi-functional and multi-objective, the NLSC held a "National e-GPS Base Stations Real-time Kinematic Positioning System" exhibition at the international conference room on Kuangfu Campus of National ChengKung University on December 1, 2006 as part of a series of celebration activities for the 60th anniversary of the NLSC’s establishment. The exhibition was included as part of the 7th International Symposium on GSP Satellite Technology sponsored by the SatelliteGeoinfomaticsResearchCenter, NationalChengKungUniversity. The exhibition was hosted by Hsiao, the former director, with honored guests such as the Deputy Minister Chung-Sen Lin, Ministry of the Interior; Wu Wan-Shun, former head of Land Administration Department, Ministry of the Interior; Professor Shih Hui-Shun, founding department head of the Survey Engineering Department, National ChengKung University; Principal Yang Chieh-Hao, Ching Yun University; and Director Chang Ke-Chin, General Research Center, National ChengKung University invited to give exciting speeches. 345 guests showed up and two forward-looking lectures were given - “e-GPS Application Services and Precision Verification” by Professor Chen Chun-Sheng, Vice Principal of Ching Yun University, and "Today's Ideas, Tomorrow's Possibility – Single-point Precision Positioning" by ProfessorTseng Ching-Liang of NationalChengKungUniversity. Besides, the dynamic display of system operation and system building process were presented along with five static displays of related research and test results. As regards the two major resources produced by the system, which includes post-processing of satellite observation data and real-time kinematic positioning, the NLSC has made them fully open to the public in 2007 for free trial.

 e-GPS real-time kinematic positioning system exhibition

 

IV. Undertaking Fourth-orderControl Survey and Supplementary control Survey

Taiwan's rapid socio-economic development has triggered high degree of land development. All major construction projects sponsored by the government are required to go through control survey, with results to be used for land planning. According to Cadastral Survey Implementation Rule No. 12, the fourth-order control survey has been consigned to the NLSC for cadastral survey and results review, filing and management, based on the proclamation of authority (Ministry of the Interior) – December 12, 2006, Tai NeiTi zu Ti 0950188002 Announcement. In accordance, in order to maintain the conformity of national coordinate system, the NLSC has started undertaking consignment made by institutions and parties regarding fourth-order control survey and supplementary control survey. In the period between 1998 and 2007, the NLSC had consigned 76 cases of control survey and supplementary control survey, and created 3029 new fourth-order control points and 16,041 newsupplementary controls.

2008 Work List for Consigned Fourth-orderControl Survey andMap RootSurvey

V.Velocity Field Survey and Maintenance of Control Point

Situated in the violent collision zone between the Eurasia Plate and the Philippine Sea Plate, crustal movements have caused displacement of control points and severe twist of coordinate system. As a result, a velocity field model should be constructed for all orders of control points for analysis of impact created by crustal movement on coordinate system. Starting from 2008, in support of the “National Surveying and Mapping Development Plan” as sponsored by Ministry of the Interior, the NLSC has used e-GPS real-time kinematic positioning survey technology to coordinate the third-order precision control point velocity field measurements, and to manage the maintenance work. The project will continue for five years. The five consecutive years of data, together with other institutions’ information will be used for building a detailed database for Taiwan's velocity fields, which will effectively maintain the national coordinate system TWD97 framework, will further facilitate integration of related maps and data, and will ensure people’s rights of land properties.