INSPIRE Thematic Clusters

Common ETRS89 coordinates of the state borders

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Jirí Polacek opened the following discussion topic in the main group, alerting about interoperability problems of commonly agreed state boders when they are provided by different members States:

https://themes.jrc.ec.europa.eu/discussion/view/21479/common-etrs89-coordinates-of-the-state-borders

Original description from Jirí:

Common unique ETRS89 coordinates of the state borders are not only taken for granted but also crucial for crossborder data harmonization.  Taking into account large scale map themes like Cadastral Parcels and Administrative Units, we can identify particular difficulties. From the point of view of data harmonization, cadastral parcels should fit the state border and the state border should contain the same ETRS89 coordinates from both neighbouring countries.

 This premise has been tested in the frame of the ELF project. Practical experience from the Czech-Polish cluster proved that none of these assumptions has been allways met. Discrepancies between parcels (derived from the cadastral maps) and state boundaries are usually caused by mistakes in the map and are easy to fix. On the other hand, if the state boundary is measured and administered in both national coordinate systems (this way is common for the international treaty on the state boundary), the accuracy of the transformation into the ETRS89 is influenced by discrepancies of the national trigonometric network, which results in two slightly different state boundaries in ETRS89. In case of the Czech and Polish boundary, the mean deviation was approximately 10 cm.

The only solution, which enables to fix the ETRS89 coordinates on the state boundary, lies within additional GPS measurements on  state borders. This approach guarantees the accurate official ETRS89 border coordinates, which should be approved by the international treaty.  This has been recently accomplished on the Czech-Slovak state border and is being prepared for the Czech-German and.

As view and download services for cadastral parcels and administrative units themes are being run in an on-line mode in the Czech republic, a special transformation is being prepared, which will convert the local Czech coordinate system JTSK to the ETRS89 as well as preserve fixed ETRS89 coordinates on the state border.

Since the discussion topic is related to Coordinate reference systems, please use this new discussion topic in the Coordinate reference systems subgroup for further discussion.

The topic is also a cross-cluster issue, at least overlapped with the Administrative units and the Cadastral parcels themes.

Feel free to participate!

Replies

    • Public

    By Jordi ESCRIU

    Many thanks Jirí,

    This issue is also related to other INSPIRE themes outside this cluster - Cadastral parcels and Administrative units INSPIRE themes, in Thematic Cluster #6 on "Topographic and Cadastral reference Data", where Jirí also spotted this issue:

    https://themes.jrc.ec.europa.eu/discussion/view/21536/common-etrs89-coordinates-on-the-state-borders

    The issue is illustrated in the slide on page 23 of the following presentation, from the INSPIRE KEN workshop about transformation of Hydrography and Transport networks themes.

    Here you have a screenshoot of this slide.Issue State Borders

    • Public

    By Jordi ESCRIU

    Dear All,

    Find below the poster presented by Jirí Polacek (Cuzk / Czech Republic) on this subject in the INSPIRE GWF 2015, which further explains the issue.

    State Borders in ETRS89 - Poster by Jiri Polacek

    Feel free to comment on it!

    Jordi

    • Public

    By Jordi ESCRIU

    I proceed to copy here the new contribution from Jirí on this issue.


    Dear Jordi !

    Sorry for the delay, but I was searching additional information on this topic.

    From my point of view, there are 3 actions necesarry to be proceeded to solve it:

    1. State boundaries must be measured in ETRS 89 from both sides. This is not just a technical issue, but organizational as well as boundary documentation is a part of international agreement.
    2. Some additional measuring (in a buffer along the boundary) must be proceeded to eliminate discrepances on the control points, which are close to the boundary. Vectors of deviation on these points should be homogenous.
    3. Use boundary and control points with both coordinates (national and ETRS 89) to create geometrical transformation, which will fit to the boundary with satisfactory accuracy.

    The topic is discussed in a working group State Boundaries of Europe Knowledge Exchange Network (SBE KEN) under EuroGeographics. Working group has web pages : http://eurogeographics.org/knowledge-exchange/sbe-ken. Our college Jan Reznicek (on the web page is mistakenly called Reznik), who (I think) takes part in your cluster, is a member of coordination comitee of this working group.

    Best regards

    Jiri


    Please feel free to add any views on the actions proposed by Jirí.

    Jordi 

     

Elevation, Orthoimagery, Reference Systems and Geographical Grids Cluster

Elevation, Orthoimagery, Reference Systems and Geographical Grids Cluster

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