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Geodetic origin point

Geodetic origin point
  • Geodetic origin point
  • Triangulation
  • Measurement of Unified Control Point
  • Leveling
  • Gravity Surveying
  • Geomagnetism Surveying
  • Very Long Baseline Interferometry (VLBI)
Geodetic origin point
Geodetic Origin points
A. Horizontal Origin Point
  • Close-range view of the Korean horizontal origin pointClose-range view of the Korean horizontal origin point
  • Remote view of the Korean horizontal origin pointRemote view of the Korean horizontal origin point
In Korea, geodetic surveying was first carried out in Tsusima Island, Japan, and Geoje Island, Korea, in the 1910s using the triangulation method from the Tokyo Datum. However, in the 1960s, the establishment of a Korean geodetic horizontal origin point was required for the project of setting a detailed geodetic network. The National Geographic Institute (current National Geographic Information Institute) carried out detailed astronomical observation over five years, from 1981 to 1985, in order to establish the Korean geodetic horizontal origin point.

In order to adopt(or introduce) the geocentric coordinate system GRS80 reference ellipsoid the National Geographic Institute also calculated the geocentric coordinates of the geodetic horizontal origin point by observing international geodetic VLBI(Very Long Baseline Interferometry).
Korean geodetic horizontal origin point
Classification of the Korean geodetic horizontal origin point
Classification Details
Location National Geographic Information Institute, 92 Worldcup-gil, Yeongtong-gu, Suwon
Longitude 127°03'14.8913'' East
Latitude 37°16'33.3659'' North
Azimuth 3°17'32.195'' to the metal intersection point of the CORS site, Seoul National University of Science and Technology
History - August 1981-October 1985: Astronomical surveying based on Wild T-4
- December 27, 1985: Publication of results from geodetic origin point (Bessel) (National Geographic Institute Announcement No. 57)
∙Longitude: East 127°03'05''.1451
∙Latitude: Northern 37°16'31''.9034
∙Azimuth: 170°58'18''.190 (Donghak Mountain)
- October 16, 1995: Observation of the VLBI to adopt the WGS-84 (VLBI observational station)
- June 29, 2002: Calculation of geocentric coordinates of the geodetic horizontal origin point
B. Vertical origin point
From 1913 to 1916, the National Geographic Information Institute (NGII) observed the sea level of Incheon bay for three years based on tidal highs and lows, and defined the average value (mean sea level) as reference point 0.0m: the base for observing all elevations in Korea. In 1964, the NGII carried out precise leveling from this mean sea level to a benchmark located in Inha Technical College, establishing the Korean vertical origin point. The vertical origin point is 26.6871 meters high and serves as the base level for all land in Korea.

The vertical origin point was designated Cultural Heritage No. 247 and registered by the Cultural Heritage Administration on April 14, 2006.
  • Korean geodetic vertical origin point
  • Korean vertical origin point
History of the geodetic vertical origin point
The government of Korea measured height based on the average of the high and low water levels around Incheon Bay during the period between December 1913 and June 1916. This figure is referred to as the mean sea level of Incheon Bay. First, the tide level was recorded for over a year at Incheon and four other cities—Cheongjin, Wonsan, Mokpo, and Jinnampo—to calculate the mean sea level for each area. Then, setting the mean sea level as the base level for height measurement, the value for the leveling network was averaged by dividing the Korean Peninsula into northern and southern networks with a leveling route that passed Jinnampo, Pyongyang, and Wonsan. Since no observation records remain from these days, it is unfortunately difficult to access further details.

The reference point of the Korean geodetic vertical origin point, the benchmark for altitude in Korea, is the quartz plate (zero point) on the geodetic vertical origin point established on the premises of Inha Technical College, located at 253 Yonghyeon-dong, Nam-gu, Incheon, on December 2, 1963. Standing at 26.6871m above the mean sea level at Incheon Harbor, this height was obtained by the measurement unit of the NGII between February 28 and March 11, 1964. The institute divided the distance between the geodetic vertical origin point established by the former Land Survey Bureau in Incheon in 1917 and this geodetic vertical origin point into three sections and carried out a precise measurement with a Wild N3 level. The reference point for the mean sea level of Incheon was defined by calculating the mean sea level from the marigram (1/50) of Incheon Harbor from 1914 to 1916 based on the method of measuring area.
Geodetic vertical origin point
Geodetic vertical origin point
Classification Details
Geodetic vertical origin point 253 Yonghyeong-dong, Nam-gu, Incheon (In the premises of Inha Technical College)
Observation equipment Wild N3 level (Level of Precision Class 1)
Appurtenant equipment Class 1 Inver Staff
Observation method Precise measurement of dividing the distance from the geodetic vertical origin point of Incheon (5.477) established in 1917 to the current origin point into three sections
Value of vertical origin point 26.6871m
Period of observation February 28 to March 11, 1964 (Precise observation from the geodetic vertical origin point of Incheon)
Installation date December 2, 1963
Notification date March 22, 1964
Installer National Geographic Information Institute
Former geodetic vertical origin point of Incheon
Period of observation: Observing the tidal level of the coastal waters of Incheon from 1914 to 1916 (5,477m above MSL)
Registration of the Korean geodetic vertical origin point as a cultural heritage
Grounds for the announcement: Announcement of the Cultural Heritage Administration No. 2006-36 (April 14, 2006)
Registration number: Registered cultural heritage No. 247
Name of cultural heritage: Korean geodetic vertical origin point (including its protective case)
Location: 253 Yonghyeon-dong, Nam-gu, Incheon (Inha Technical College)
Supervisor: National Geographic Information Institute
Outlines of the reference origin point
    - Quartz plate (true height from reference origin point: the cross-shaped mark indicating the height of 26.6871m)
    - Protective case (the red-brick columnar construction)
    - Four complementary points (complementary reference points to restore the reference origin point in the event of its damage)
Geodetic vertical reference of islands
The geodetic vertical reference of Jeju Island, Ulleungdo, and Dokdo are to be defined and made public pursuant to Article 6 (1) 2 of the Act on Land Survey, Waterway Survey and Cadastral Records (Announcement No. 2009-1000 of the National Geographic Information Institute) December 21, 2009
President of the National Geographic Information Institute
Outlines of the geodetic vertical origin point of islands
Outlines of the geodetic vertical origin point of islands
Title Location Height Remark
Jeju vertical origin point Top of the vertical origin point sign (Jeju point) at 983-1, 1do-dong, Jeju, Jeju Special Self-Governing Province 11.1319m above mean sea level at Jeju Port  
Ulleungdo vertical origin point Top of the vertical origin point sign (15-00-18-1) at Ulleung Middle School, 223-13 Dodong-ri, Ulleung-eup, Ulleung-gun, Gyeongsangbuk-do 48.2882m above mean sea level at Jeodong Port, Ulleungdo  
Dokdo vertical origin point Top of the Dokdo station of triangulation (Dokdo 11) at 30-1 Dokdo-ri, Ulleung-eup, Ulleung-gun, Gyeongsangbuk-do 87.0610m above mean sea level at Dokdo  
C. Gravity origin point
  • Korean geodetic gravity origin point Korean gravity origin point
  • Absolute gravity system and processor Absolute gravity measurement system and processor