System Introduction

I.Origin

The Land Surveying and Mapping Act was promulgated on 21 March 2007, the reference system were released later, including Geodetic Coordinate System 1997 (TWD97), Elevation Coordinate System 2001 (TWVD2001) and Gravity Coordinate System 2009 (GS2009). The National Land Surveying and Mapping Center, Ministry of the Interior (NLSC) built "Satellite tracking station basic control point Inquiry System" to get the information, and described in detail as follows:

(1) Satellite tracking station

In recent years, satellite positioning has become increasingly widespread. Companies and units, based on their business needs, set up continuous GNSS stations to conduct accurate positioning, earthquake monitoring, measurement, and other scientific research work. NLSC has also built an instant automatic global satellite system, combining satellite positioning technique with Internet and information technology to achieve fast, accurate coordinates.

The Geodetic Coordinate System(TWD97) was started to used since 1998, due to the movement of tectonic plates, many regions have been unable to carry out high-precision measurements job. So the Ministry of Internal Affairs(MOI) invited many experts to discuss since October 2009. Finally MOI announced 18 satellite tracking stations and 219 1st order control points on March 30, 2012, named as TWD97[2010].

Although agencies build continuous tracking stations for a variety of purposes, their data can be used, shard and show the information on the web site.

(2) Basic control points

According to The Land Surveying and Mapping Act, the basic control points measured by the satellite positioning method are known as satellite control points, points using benchmark and gravity measurements standard referred to as benchmark points and gravity points. All the announced results shall be published.

1. Satellite control points

Beginning in 1993, after considering the traditional triangulation points and the satellite points established by the Academia Sinica, MOI announced the the result on 1998, including 105 control points(1st order) and 621 control points(2nd order). From 1995 to 2003, NLSC used the satellite positioning technique to build 4710 control points(3rd order)to increase the control point density.

To maintain the accuracy, MOI announced new result on March 30, 2012. The result is including 105 control points(1st order), 569 control points(2nd order) and 2102 control points(3rd order).

2. Benchmark Points

The construction of a national altitude control system is very useful for monitoring the subsidence of the ground, controlling the groundwater position, building and protecting tunnels and subways, highways system, speed boats, flood protection system, bridges, reservoirs and other economic facilities. Because Taiwan is located in an area where tectonic plates are very active, it is necessary to periodically carry out new measurements and publish results to ensure completeness and accuracy.

The construction of the national altitude control system is usually carried out by leveling measurement method with high accuracy. MOI announced the measurement standard named TWVD2001 and 2,065 benchmark points from 1999 to 2003. These results were measured and announced 2,084 benchmark points in 2009, 2,461 benchmark points in 2016.

3. Gravity point

Since 2003, MOI has planned to build a national standard gravity station.The gravity croordinate system announced(GS2009) in 2009, the measure results were include 2 absolute gravity points(in 2009), 17 absolute gravity points, 683 1st gravity points, 6,084 2nd gravity points.

II. Introduction about construction result

The launch of this information system, the originally was to share the GNSS data and information between the organizations. The goal was extended by publishing the station information to the public and putting the basic control points information together since 2015.

Map display functions include zoom in, zoom out, zoning, entering the administrative area name, satellite owners, coordinate system for search, to avoid duplicate construction that wastes resources.

III. Limitation of use

(1) Sattelite station

Maps can be viewed for search of information on name of the GNSS stations and station construction Owner’s information.

Agency, unit Licensing regulation
Central Geological Survey,MOEA
Website \ Relevant regulations \ Page 2 \ Regulations on application for license and fee collection of geological data warehouse, Central Geological Survey
Water Resources Agency,MOEA
Purpose, plan and dispatch applying for use of GNSS observation documents

10651 Level 9-12, No. 41-3, Lot 3, Tin Nghia Street, Dai An District, Taipei City

Institute of Earth Sciences, Academia Sinica
(include Taiwan Volcano Observatory - Tatun)
Purpose, plan and dispatch applying for use of GNSS observation documents

No. 128, Lot 2, Research Institute Road, Nam Pang District, Taipei City 115

Central Weather Bureau
Home page applying for license to use document of Central Weather Bureau
Taipei City Government

Land Development and Exploitation Team Taipei City Bureau of Land Administration (Phone: 02-87807056, 303 Branch)
1. Notice
2. Application for use of document

Taichung City Land Bureau

Taichung City Cadastral Bureau (Tel: 04-22170518)

Tainan City Government

Measurement Department of Tainan City Land Survey Bureau ( Tel: 06-6355308)

Ministry of Internal Affairs
Satellite Measurement Center Land Survey Department Ministry of Internal Affairs

Ministry of Internal Affairs e-GNSS instant positioning system, national measurement center

◆ Kaohsiung City
◆ Forestry Bureau
◆ NLSC
◆ Hsinchu County Government
◆ Changhua County Government
◆ Chien Hsin University of Science and Technology
e-GNSS instant positioning system, national measurement center

Collection charge and preference: Website\about e-GNSS\current charge

Applying method: Website \applying method

Industrial Technology Research Institute
use documents or e-mail
195, Sec. 4, Chung Hsing Rd., Chutung, Hsinchu, Taiwan 31040, R.O.C.
Manager:Mr.Chien
(Phone:886-3-591-8578,e-mail:jengming@itri.org.tw)

(2) Baseline control points

The system supports finding the distribution of location points, coordinates of the point locations, data can be logged and get the detail from https://whgis.nlsc.gov.tw/

(3) Densified control points (detail measurement results are in the system of cities.)

No. Centrally-governed, district control point information system Construction method
1 Control point information system of Kaohsiung City NLSC supports construction
2 Control point information system of Tainan City NLSC supports construction
3 Control point information system of Keelung city NLSC supports construction
4 Control point information system of Hsinchu City NLSC supports construction
5 Control point information system of Miaoli City NLSC supports construction
6 Control point information system of Changhua City NLSC supports construction
7 Control point information system of Nantou City NLSC supports construction
8 Control point information system of Chiayi City NLSC supports construction
9 Control point information system of Chiayi City NLSC supports construction
10 Control point information system of Yunlin City NLSC supports construction
11 Control point information system of Yilan City NLSC supports construction
12 Control point information system of Hualien City NLSC supports construction
13 Control point information system of Taitung City NLSC supports construction
14 Control point information system of Pingtung City NLSC supports construction
15 Control point information system of Penghu City NLSC supports construction
16 Control point information system of Kinmen City NLSC supports construction
17 Measurement result management system of Taipei city constructs by themselves
18 Control point information system of TaiChung City constructs by themselves
19 Densified control point information system of New Taipei City constructs by themselves
20 Control point information system of Taoyuan City constructs by themselves
21 Control point information system of HSINCHU City constructs by themselves