Creating and updating of topographic maps height base in the new national spatial coordinate system: case Fergana valley

The use of high-precision technology the global navigation satellite system (GNSS) has put forward task developing methods for creation and a new national open coordinate in Republic Uzbekistan. In country, up to now CS42 system, based on Krasovsky ellipsoid used geodetic works. Baltic normal heights (1977), tied mean sea level with zero mark Kronstadt tide gauge, was adopted as height datum. Due lack geoid information territory country determined by modern methods, realization reference datum becomes an urgent task. results GPS measurements usually presented relative WGS-84 ellipsoid, have convert national, local systems solve practical problems. horizontal coordinates can directly computational work, but orthometric (or normal) given area using information. this study made updating topographic maps at scale 1:200,000 deformation matrix between two Fergana Valley. To WGS84 systems, vertical GTX format National oceanic Atmospheric Administration Canada (NOAA) created. create file elevation displacements, classical leveling 144 “common” points entire network known systems. difference “real” values obtained from “modeled” ranges -0.13 m 0.67 m. It revealed that maximum differences are basin itself may be consequence both anomalous gravitational field part territory, insufficient density stations northeastern area. updated map computed EGM2008 high precision geopotential model. discrepancy is range -3.93 0.31