- Process data of measurements of national GNSS CORS network simultaneously with IGS data to link international coordinates, update on coordinates according to the dynamic reference syst
Trang 1HANOI UNIVERSITY OF MINING AND GEOLOGY
BUI THI HONG THAM
RESEARCH ON THE THEORETIC BASE FOR THE MODERNIZATION OF THE NATIONAL GEODETIC CONTROL NETWORK IN VIETNAM BY GLOBAL NAVIGATION SATELLITE SYSTEM GNSS
Specialty: Geodesy and Mapping
Code: 62520503
SUMMARY OF THE THESIS SUBMITTED FOR THE
DEGREE OF DOCTOR
HANOI – 2014
Trang 2surveying, of Surveying Faculty, Hanoi University of Mining and
Geology
Scientific Supervisors:
1 Prof Dr.Sc Dang Hung Vo
Association of Geodesy, Maps and Remote Sensing of Vietnam
2 Dr Vu Van Tri
Hanoi university of Mining and Geology
Examiner 1: Dr Le Minh
Association of Geodesy, Maps and Remote Sensing of Vietnam
Examiner 2: Dr Nguyen Dinh Thanh
Defense Mapping Agency of Vietnam - Ministry of National
Defense
Examiner 3: Dr Tran Hong Quang
Association of Geodesy, Maps and Remote Sensing of Vietnam
The dissertation will be defended at the University examination Council at the Hanoi University of Mining and Geology, at… h,
……… 2014
This dissertation is submitted to National library and library of Hanoi University of Mining and Geology
Trang 3INTRODUCTION
1 The importance of dissertation
The launching of global navigation satellite system (GNSS) opened a new era for sciences – technology, especially surveying - mapping GNSS has changed basically in the conceptualization and methodology to position points on the ground due to its advantages According to the national controling network, GNSS applications can
be divided into two phases:
- Authenticate, increase points, improve the traditional coordinate network;
- Establish the national coordinate network under a new concept based on the ability of GNSS technologies
Currently, national coordinate network in the world are ordinarily built on GNSS continuously operating reference stations with consistent density, appropriated accuracy, reliability, safety and multi – purposes This is called the GNSS CORS network The name describes technologically "continuous observation to connect points in
an online network system." Density and distribution of points varies from country to country
In Vietnam, the traditional network was upgraded preciseness, improved and modernized by GNSS technology to become national georeference system VN - 2000 This made a milestone of surveying and mapping science of our country
In face of the achievements in the world, it is essential to build continuously the geodetic coordinate network by GNSS technology to replace traditional geodetic network and meet the modern demands of the coordinates GNSS technology applications are the most basic component of geographic information infrastructure and become a trend in the world, so we have to integrate without any other options The Ministry of Defense has been executing the project of constructing the military georeference system GNSS CORS network (finished on 1/2 block workflows), Ministry of Natural Resources and Environment has built and implemented Strategy of measuring and mapping development, of which the modernization of coordinates and leveling network system is the main point (consideration to approval) Although there are scientific basis and practical studies to apply, there has been no thesis which does research in a systematical way of
Trang 4building modern geodetic coordinate network, multi-purposes to meet the demand and integrate development of geographic information in
the world "Research on the theoretic basis for the modernization of
the national geodetic control network in Vietnam by global navigation satellite system GNSS" focuses on the issue
2 Objective of the dissertation
Provide scientific and practical foundations for the modernization
of geodetic control network of Vietnam, serving multiple purposes (surveying - mapping, navigation, researching on modern crustal movements, international information integration, ) based on GNSS technology
3 Subjective of the dissertation
The subjective of the dissertation is the national control network
in Vietnam and the applications of GNSS technology
4 Scope of the dissertation
In terms of science: Feasibilities of GNSS technology (global, continuous-time, methods of measurement, accuracy, reliability, achievements and international experience, ) Data processing of the actual stations continuously demonstrates how to connect coordinates, define and coordinate transformation, velocity of movements in the international coordinate systems ITRF Solutions, methods to build the geodetic network are to establish a unified coordinate base in surveying and mapping, solve the problem of positioning reference system and scientific research to Earth
In terms of space: The national geodetic coordinate network can connect with the international coordinate network IGS
In terms of time: It is counted since Vietnam constructed the traditional geodetic network
Trang 5cadastral and construction), monitoring crustal movements, building the national reference system according to the dynamic point of view
- Process data of measurements of national GNSS CORS network simultaneously with IGS data to link international coordinates, update
on coordinates according to the dynamic reference system point of view, and observation of modern crustal movements
6 The methodology
The dissertation using the following methodologies:
- Methods of synthesis, analysis and inheritance: Collect the historic documents; update the information on the internet, synthesis, analysis of resources and research results, inherit selectively achievements related to the subject
- Methods of collection and processing GNSS data: static measurements, session 24/24 at the continuous measurement points Processing of measurements and IGS data by Bernese 5.0 software, connect coordinates, velocities with IGS network, scalability coordinates, and velocities in the typical dynamic coordinates system ITRF
- Methods of comparisons: Compare the advantages and disadvantages of building geodetic control network according to the traditional method and the method using GNSS technology
- Methods of expert: Learn more knowledge and experience from experts
- Method of application of information technology: using programming languages; setting up spreadsheets to automate the calculation process
7 Scientific and practical meaning of dissertation
- The scientific meaning of dissertation: Approach a further step when to learn about the development of GNSS technology and provides reliable scientific foundations of GNSS technology applications in building modern geodetic coordinate network, multi - purpose consistent with the reality in Vietnam and connect with the world
- The practical meaning of dissertation: The results of the dissertation have contributed to the selection of the appropriate solution to modernization geodetic coordinate network, reference system in Vietnam
Trang 68 Rational arguments and new contributions
a Rational arguments
- First argument: According to a new point of view, National
coordinate network in Vietnam is GNSS CORS network with appropriate infrastructure (receiver, antenna, augmentation systems, information infrastructure, network connectivity, ) meeting modern measuring methods; solving the task of defining and maintaining the coordinate reference system; the detailed measurement for setting up mapping; tracking and navigation; researching on modern crustal movements
- Second argument: because of the structure and density of the GNSS CORS network, methods of collecting and processing relevant data, the national network entirely meet the needs of the surveying and mapping, international connections of geographic information; carry out Earth scientific research in Vietnam according to global standards
- Third argument: The national geodetic coordinate network in Vietnam based on GNSS technology has high performance (advanced accuracy, extend technical scope, timely updates and automation)
b New contributions
- To put forward a GNSS CORS network in Vietnam with full scientific and practical foundations
- To prove the necessity of building a dynamic reference system
in Vietnam by specific data
- To propose the time to update the new coordinates for the GNSS
CORS network in Vietnam
- To put forward the workflow of coordinate transformation, velocities of GNSS points between international terrestrial reference frames ITRF using 14 transformation parameters
- To establish the velocity diagram of GNSS points in Vietnam in
a coordinate system
9 Structure of dissertation
The structure of dissertation includes three main parts: introduction, content as well as conclusions and recommendations, which is presented on 132 pages, 25 drawings and diagrams, 34 tables
Trang 7Chapter 1
OVERVIEW OF APPLICATION OF GPS TECHNOLOGY
IN BUILDING COORDINATE NETWORK SYSTEM
1.1 Application of GNSS technology in the construction of geodetic network in the world
GNSS has become a major technology and has gradually replaced the traditional measurement technology in the construction of geodetic network
1.2 Application of GNSS technology in the construction of geodetic network in Vietnam
From the overview picture of the development of GNSS technology in the world and the process of applying GNSS technology
in Vietnam, it can judge the trend of GNSS technology applications in Vietnam Specifically, GNSS technology helps reduce working time with low cost and high-tech capabilities Furthermore, it provides favorable conditions to change significantly the conceptions and forms
of the national coordinate control network, specifically including:
- Formatting many tiers with dense buried points of the traditional manner has been replaced by the form of the base GNSS CORS network with very little buried points, which creates a new method of determining the number and distribution of buried points at the last grade for measuring detailed topography, objects This is a new form
of national coordinate control network; we have not approached "The Concept of No - Network Geodesy" but access "low density geodetic network "
- It is possible to identify the local geoid model with high accuracy, the combination of coordinate and leveling network in a GNSS CORS network measured leveling is a new approach to unified coordinates - leveling control network
- The dynamic geodetic GNSS network depending on time is a new approach to the national georeference system, suites Earth observation associated with the new tectonics The application of this approach in each country associated with the international reference system requires detailed studies
Therefore, the direction researching of the dissertation has been laid out and presented in section 5 Content of dissertation in the beginning of the dissertation
Trang 8Chapter 2
STUDYING THE POSIBILITY OF GNSS TECHNOLOGY APPLICATIONS TO CHANGE THE NATIONAL HORIZONTAL
NETWORK IN VIETNAM
2.1 The general problem
2.1.1 Conception changes of form, structure, precision of control network since the GNSS technology was born
- Changes of the application structure of GNSS
Figure 2.1 The application structure of GNSS technology [50] Currently, there have been fundamental changes in GNSS in terms
of technology on promoting positioning under the new approach With the present concept, the application structure of GNSS technology is expanded (Figure 2.1)
- Development trends of measurement methods
The principle of measuring real-time NRTK starts with all reference stations in these network online observing satellites continuously with the software system installed on the master system
GLONASS
GALILEO
EGNOS WAAS MSAS
EUPOS SAPOS
Trang 9The aim of NRTK is to minimize the impact of the error depended
on the distance and location calculated within the network Minimizing sources of error in the measurement process is different when the technology used NRTK in is different (MAC, FKP, VRS, ) Each technology will lead to significant differences in performance, reliability and accuracy for rover stations
- Geodetic control network under the new perspective is integrated geodetic points, based on the existing geodetic infrastructure of each country and GNSS technology to exploit efficiently for practice and scientific research The network is based on the following principles:
+ The network must be durable and long lasting;
+ Reasonable density, data in the plane reference, leveling and gravity system;
+ To be the basis for national geodetic reference system;
+ To meet the applications when using of modern surveying technology
As a result, geodetic control network under standpoint ensures the capacity to provide data about the shape, size, gravity field of the Earth, as well as the volatility of quantities over time This network has the following tasks:
- Navigation and tracking: error millimeters
- Surveying and mapping: error position about centimeters
- Research and identify crustal movements: error millimeters
- Supporting research atmosphere,
2.1.2 The method of construction GNSS CORS network playing basic geodetic plane network in the world and Southeast Asia
Today, so many GNSS CORS networks have been established in the world, which are the major infrastructure to provide the necessary applications with high accuracy in surveying, mapping, navigation and the Earth science applications The countries which have set GNSS CORS network have to follow the legal and the rules of the countries Moreover, the countries with great potential of sharing the network also cooperate to form GNSS CORS networks of the region
Trang 102.1.3 Some features when building GNSS CORS network
The main advantages of the GNSS CORS network: reducing depended error sources due to the connection of the permanent stations
to produce the network, the longer distances of points in the GNSS CORS network results in decreasing the number and density of the points, and automating the GNSS measurements referencing , calculation results to unified reference frame
2.2 The ability to change the horizontal control network in Vietnam by the method of construction GNSS CORS network
The control plane network in Vietnam in the future will be the GNSS CORS network (NRTK CORS), which has distance and appropriate accuracy to satisfy most missions
Table 2.1 The number of GNSS CORS stations in Vietnam
N 0 Distance of a GNSS
CORS (km)
Control area of a GNSS CORS (km 2 )
The number GNSS CORS
2.3 Construction GNSS CORS network in Vietnam
2.3.1 The idea of the tier the national GNSS CORS network, structure, density and accuracy
The idea of construction GNSS CORS network in Vietnam must
be multi-purposes network service, and satisfy most missions presented in Table 2.2
Trang 11Table 2.2 Mission and accuracy requirements of the national GNSS
CORS network
requirements
1 To satisfy the requirements of measurement
basic maps as terrain mapping ≤ 10 cm
2 To satisfy the requirements of cadastral ≤ 4 cm
3 To satisfy the requirements of navigation and
4 To satisfy the requirements of researching
5 To satisfy the requirements of establish the
6
To connect with IGS, the network has some
points of attributes IGS to resolve international
scientific tasks regionally and globally
- The sum of the national GNSS CORS network is calculated when this network satisfies the requirements of measurement basic maps - the third GNSS CORS stations
- Some of the third GNSS CORS stations will be selected to meet the mission of the first and the second GNSS CORS stations
- Some of the second and the third GNSS CORS stations will be selected to meet the mission of the first stations
- One GNSS CORS station is able to satisfy many different tasks Table 2.3 Recommended the number of GNSS CORS stations
Vietnam Area
(km 2 )
Distance (km)
Control area of a GNSS CORS (km 2 )
The number GNSS CORS
Trang 12The national geodetic control network will be modernized by GNSS CORS network with minimum and reasonable density of points, consistent and sustainable, including 79 points, in which:
- 4 points join to IGS - tier 1;
- 8 satisfy the requirements of setting up the national geodetic reference Reward - tier 2;
- 11 satisfy the requirements of researching modern crustal movements - tier 2;
- 4 points has DGPS service functions that satisfy the requirements of navigation and tracking - tier 3;
- 79 points satisfy the requirements of measurement basic maps - tier 3
* Comment
Figure 2.2 shows that the application of GNSS technology has changed the traditional network in both structure and density The new one is multi-purpose network; satisfies the requirements of modern surveying; guarantees for solving the task of verifying and maintaining the reference frame, coordinate system; satisfies the requirements of measurement basic mapping; navigation and tracking; researching modern crustal movements
79 points in the national GNSS CORS network are designed on the base map of Vietnam Some points in the network serve many objectives when building the GNSS CORS (eg points in MongCai cover five functions: join IGS, build the national geodetic reference frame, research modern crustal movements, navigation and tracking and serves basic mapping)
In the process of building the national modern geodetic network, some points in VN - 2000 satisfying the requirements will be selected
as the points of the national GNSS CORS These points in two networks will serve for the determination of coordinate transformation parameters This will ensure that close link between the old and new network as well as the unified use of two networks
The above analysis proves the capacity and accuracy of GNSS technology in the current period, shows technical efficiency (improves
Trang 13the accuracy and expands the technical scope, timely updates, automation, ) indisputable of this technology when applied for the construction of the national geodetic network in Vietnam
Figure 2.2 The GNSS CORS network in Vietnam
Research function geodynamics; : DGPS function; : Joined on IGS The green area indicates three main economic Northern, Central, Southern The green lines separate territorial Vietnam into blocks according to the documents [6]
2.3.2 Principles of organization, construction and operation of GNSS CORS network
Each GNSS CORS station has minimum requirements on many aspects of the construction process and operation
MALAYSIA
TruongSa Islands
(Vietnam)
Trang 14Chapter 3
THE NATIONAL HORIZONTAL NETWORK FOR MORDEN
CRUSTAL MOVEMENTS RESEARCH
3.1 Scientific and practical significance of researching modern crustal movements in intercontinental and global scale
Over time, GNSS technology is growing and perfect, problems of geometry and physics of the Earth is resolved Until now, this technology has completely satisfying scale of studies, the accuracy required for the job posting This is the basis to take form concepts of dynamic geodetic
3.2 The network monitors modern crustal movements and achievements when applying GNSS technology
The determination of the Earth's crustal movements requires the highest accuracy and compliances with rigorous technical process at any scale Presently, the realities have demonstrated that this technology can fully satisfy the accuracy requirements
3.3 Monitoring modern crustal movements in Vietnam
In Vietnam, the monitoring system using GNSS technology has been implemented to create a database growing richer These findings have contributed to geodynamic map of the region in more detailed, accurate and reliable way
3.4 Adjustment DGPS/CORS on the international reference system
3.4.1 Measurement data
Table 3.1 Synthetic measurement data
MCRS DNRS PQRS TSRS KUNM NTUS PIMO WUHN