6.4.10 Coordinate referencing

From Geostandards

INSPIRE aims at limiting the number of coordinate reference systems and map projections to ensure a common basis for the geographical harmonisation.

For the horizontal component, INSPIRE will use the European Terrestrial Reference System 1989 (ETRS89) for the areas within the geographical scope of ETRS89. The International Terrestrial Reference System (ITRS) or other geodetic coordinate reference systems compliant with ITRS will be used in areas that are outside the geographical scope of ETRS89. Compliant with the ITRS means that the system definition is based on the definition of the ITRS and there is a well established and described relationship between both systems, according to EN ISO 19111.

The following map projections apply:

• Lambert Azimuthal Equal Area (ETRS89-LAEA) for pan-European spatial analysis and reporting, where true area representation is required;
• Lambert Conformal Conic (ETRS89-LCC) for conformal pan-European mapping at scales smaller than or equal to 1:500,000;
• Transverse Mercator (ETRS89-TMzn) for conformal pan-European mapping at scales larger than 1:500,000.

For regions outside of continental Europe, for example for overseas territories, suitable projections will be used and specified according to EN ISO 19111.

For the rendering of spatial information for INSPIRE View Services, and in case there is a need for plane coordinates, the “Plate-Carrée” projection is recommended for the non-polar regions. For the polar regions a Polar stereographic projection is recommended.

For the height component on Land, INSPIRE will use the European Vertical Reference System (EVRS) for the areas within the geographic scope of EVRS. Other vertical reference systems related to the Earth gravity field shall be used to express gravity-related heights in areas that are outside the geographical scope of EVRS.

For depth values of the sea floor in marine areas with an appreciable tidal range, INSPIRE will use the Lowest Astronomical Tide, as already mandated by Technical Resolution A2.5 of the International Hydrographic Organisation (IHO). In marine areas without an appreciable tidal range, in open oceans and effectively in waters deeper than 200m tide is not measured since it has no significant impact on the accuracy of the sounding.

There are however themes for which in addition to linear systems (that are usually used for the horizontal component) parametric, or on non-length-based systems are used for the vertical component. For the referencing by parameters ISO 19111-2 will be applied.

INSPIRE will use the ISA (ISO 2533:1975, International Standard Atmosphere) as the vertical reference system for the free atmosphere, and barometric pressure for the free ocean.

There are also themes that may require temporal references.

For spatial data using quadrilateral two-dimensiaonal grids for indirect geo-referencing (typically coarse resolution and wide geographical extent), the grid system used in INSPIRE is based on the ETRS89 Lambert Azimuthal Equal Area coordinate reference system with the centre of the projection at the point 52º N, 10º E and false northing: Y0 = 3210000 m, false easting: X0 = 4321000 m.

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