Abstract: RTK height fitting method based on DT mesh can not obviously improve the external coincidence accuracy in the case of fewer fitting points. Two methods to improve the external coincidence accuracy of triangular mesh are proposed. In the first method, the minimum external coincidence accuracy is regarded as the limit criterion for triangular mesh connection without consideration about the characteristics of DT mesh. In the second method,both detection points and fitting points are used to generate a DT mesh which makes the external coincidence accuracy achieving the optimal value. Results show that these two methods can effectively improve the fitting
accuracy of triangular meshes, and can meet the fourth-class leveling standard of engineering survey application.

Key words: RTK, height fitting, external coincidence accuracy, triangular mesh