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 | |
| Taipei City Government |
Land Development and Exploitation Team Taipei City Bureau of Land Administration (Phone: 02-87807056, 303 Branch) |
| 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 | |
|
◆ 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.)