A CORRECTION MODEL OF HORIZONTAL COORDINATE FOR ITRF2005 TO ITRF2008 OF THAILAND

Abstract

Nowadays, the International organizations have been improving the ITRF (The International Terrestrial Reference Frame) in accordance with plate tectonics. Thailand organizations, especially the Royal Thai Survey Department (RTSD), which is the main department that defines Zero Order Geodetic Network in Thailand, based on the ITRF2008 at epoch2013.10 since 2014, that is the latest updated and currently used. The aim of this article is to generate the correction model of horizontal coordinate for the ITRF2005 to ITRF2008 in Thailand, consists of (1) Transformation Parameters are used to transform the three-dimensional (Cartesian Coordinate) with 7 parameters (Helmert Transformation) and (2) Grid Residuals are used to interpolate of 4 methods: IDW, Natural Neighbor, Kriging and Spline, then assessment of the horizontal accuracy with the Root Mean Square Error (RMSE) with 100 check points distribute throughout Thailand. The results show the correction model of horizontal coordinate by using the IDW, Kriging, Natural Neighbor and Spline methods give the horizontal accuracy at 2.1, 2.2, 2.3 and 2.4 cm respectively. Thus coordinate transformation can be accurately in accordance with tectonic plate movement according to international standards and connecting the coordinate of the department in Thailand. Also used to apply the correction model of horizontal coordinate to other ITRF in the future.