Interpulation of Geoid Undulation

Abstract

Interpulation of geoid undulation this is to find the average value of geoid undulation database in development of precise geoid model of thailand project. By using bi-linear equation, bi-quadratic equation and bi-cubic equation to compare calculate with find geoid undulation by program of development of precise geoid model of thailand project.

Geoid Undulation is the vertical distance between the ellipsoid surface with the geoid surface or mean sea level surface. The ellipsoid was used (World Geodetic System 1984: WGS84) and the geoid was used spirit leveling or gravimetry. Geoid undulation are very important to measurement survey with global navigation satellite system (GNSS) the height value is the ellipsoid height, which is required in construction the height value want above mean sea level (Orthometric Height)

Database in development of precise geoid model of thailand project at one minute resolution or a grid distance of approximately 1852x1852 m. The initial latitude at 3 degrees north, longitude at 95 degrees east. The 780 column 1200 row grid is a database for interpolation to find the mean geoid undulation. By creating a model on the excel program and compare geoid undulation value from the bi-linear equation, bi-quadratic equation and bi-cubic equation

Interpulation of geoid undulation was used with 411 data. The difference geoid undulation was obtained from the bi-linear equation maximum 0.032 m. minimum 0.000004 m. and difference range 0.000004-0.001 m. are 299 data, the bi-quadratic equation maximum 0.025 m. minimum 0.000001 m. and difference range 0.000001-0.001 m. are 319 data, the bi-cubic equation maximum  0.025 m. minimum 0.000002 m. and difference range 0.000002-0.001 m. are 303 data.