Geodetic Control at the Territory of the CR – Additional Information

There was built the planimetric, altimetry and gravity geodetic control in the past in the Czech Republic. Since 20´s of the last century at that time high quality reference framework has been created at the territory of the Czech Republic, determined in all three components, meeting fully the demands of follow-up detailed surveying, surveying of parcel borders, line and other constructions etc. Ground control became the basis for defining of the gradually introduced and utilized coordinate systems.

As for geodetic control administration following works are carried out:

  • Investigation of the existing state of the survey marks in the field, taking measures for their maintenance or renewal according to the technical differences of individual point categories,
  • Monitoring of ground control homogeneity and their necessary refinement,
  • Proceeding regarding setting, shift or removal of survey marks of survey control points (included protecting and marking elements),
  • Stating conditions for protection or limited use of survey control points,
  • Administration of data bases and documentation of survey control points
  • Information provision about survey control points.

Rapid start of new technologies regarding the position determination, particularly global navigation satellite systems GNSS enabling automated processing of results and adjustment of large geodetic networks, transition from support of national systems towards development of continental and global reference geodetic systems and towards monitoring geodynamic stability influences, are changing the approach to maintenance of coordinates´ parameters, usage flexibility of survey control points and as a consequence the way of their setting and monumentation in the field. These facts resulted in 90´s of the last century in realization of two fundamental projects in the most used category of survey control points – planimetric ground control:

  • Project of connection of planimetric ground control of the Czech Republic to the European reference frame EUREF followed by the realization of the geocentric coordinate system ETRS89 and determination of coordinates of sufficient number of trigonometric points in this system. These points density was stated as 4-5 trigonometric points per one triangulation sheet. The project has been step by step realized by surveying of 3 points of triangulation datum in the international surveying campaign EUREF-CS/H/91, followed by construction and surveying of geocentric coordinates of the network of zero order – NULRAD (10 points), by its aerial completing and evolving into the DOPNUL network (containing 176 points) and by final densification into the network of chosen trigonometric points with geocentric coordinates surveyed directly with the number of 3 096 points at the whole territory of the CR. Realization of this project started in 1996 and was completed in 2006.
  • Project of the revision of existing points, completing and positional determination of new densification points with help of GPS technology with accuracy comparable to the one of trigonometric points at the whole territory of the CR excluding the forest complexes. Project is being realized by the cadastral offices. It was launched in 1994 and completed during 2004-2006 according to the difficulty in single regions with result of 35 000 monumented densification points located in such a way which enables direct and easy use for follow-up detailed survey.

The results of previous projects were used for creation of new realization of the ETRS89 system at the territory of the CR based on processing of time observation rows of the GNSS network of permanent stations of the Czech Republic (CZEPOS) and further chosen permanent stations at the CR territory as a follow-up to foothold stations of the European network of permanent stations EUREF (EPN).

The main goal of geodetic control activities is to define and maintain the spatial position of the geometry base of the state, in following geodetic reference systems: national system (S-JTSK), European geocentric system (ETRS89), international Baltic Vertical Datum - After Adjustment (Bpv.) and international gravimetric system S-Gr95.
Current means of surveying and information technology together with economic reasons need other system of building, maintenance and documentation of geodetic control points than the traditional one used to be. The new system of administration is based on:

  • Periodical maintenance and renewal solely of chosen survey control points,
  • Dynamical maintenance of survey control points only in the areas with high number of reported damages   ,
  • Administration of unified database on ground control points providing other information systems and databases (ISKN,ZABAGED etc.) with chosen data and being accessible via internet,
  • Increase of physical and legal protection of significant survey control points,
  • Increase of real estate owners awareness about importance and significance of survey control points located on their properties for their protection improvement and cost decrease regarding the renewal of damaged points (particularly in minor geodetic control).