Solution to Improve the Horizontal and vertical Position Accuracy of Points Measured by GNSS/CORS Technology in Creation of Large-Scale Topographic Maps in Vietnam

Abstract

In Vietnam, when creating large-scale topographic maps using Global Navigation Satellite Systems (GNSS) technology combined with
Continuously Operating Reference Stations (CORS) and traditional electronic total station measurements, there will be shifts in both
horizontal and vertical positions. To address this issue, we perform map adjustments by updating the map in an assumed coordinate
system. In the assumed coordinate system, the shapes and elevation differences of the changed objects are accurately observed to meet
the requirements corresponding to the map scale. The coordinates and elevations of clear points on the map or control points in the
field obtained from different methods have differences that are larger than the permissible values according to the map scale. Applying
a 2-dimensional coordinate transformation and the geoidal height calculated for each point with its weight, the coordinates and
elevations of the points can be computed in a unified coordinate system.