GRIDER

According to the current Law on Survey and Cadastre from 2009, the position of points in the horizontal reference system is expressed by two-dimensional, rectilinear coordinates in the plane of the conformal Universal Transverse Mercator projection - Universal Transverse Mercator - UTM, on the GRS 80 ellipsoid.

The coordinates in the Gauss-Kruger projection on the Bessel ellipsoid have been previously in use.

The connection between these two coordinate systems is achieved through 5374 points, which have determined coordinates in both systems. The transformation is carried out according to the seven-parameter similarity transformation method and position correction using the grid of residuals.

This method of transformation enables uniform accuracy of the transformed coordinates on the entire territory of the Republic of Serbia at the level of 10 cm.

The transformation is performed using the GRIDER 3.1 software, which has the following functional models:

• Transformation of spatial coordinates from the ETRF2000 system into positional coordinates of the Gauss-Krueger (GK) system and vice versa. The transformation model is 7P+GRID of residuals.
• Interpolation of height anomalies from the quasigeoid model SQM2011 and calculation of heights (NVT2 system) from spatial coordinates in the ETRF2000 system.
• Transformation of heights from the precision leveling system (TRIESTE datum) to the NVT2 system (FR-NVT2 datum) and vice versa.
• Transformation of coordinates from the 6th to the 7th coordinate system and vice versa.