The web map is presented in ETRS89-LAEA, EPSG:3035. This Lambert Equal Area projection is particularly suitable for pan-European maps with preserved area. The largest distance errors in the Baltic Sea area occur in the Northern Bay of Bothnia and reach ca. 0.7%. In all other areas of the Baltic Sea, distance errors are significantly smaller.
Data downloads and OGC services
All data downloaded through the web map download function is provided in ETRS89 geographic coordinates, EPSG:4258. For grid cells of 500m ╳ 500m, ETRS89 and WGS84 may be considered equal in the Baltic Sea area.
The OGC services for downloading imagery and data support the following coordinate systems:
- EPSG:4258 ETRS89 Lat/Lon
- EPSG:4326 WGS84 Lat/Lon
- EPSG:3006 SWEREF99 TM
- EPSG:3035 ETRS89/LAEA
- EPSG:3044 ETRS89/ETRS-TM32 (synonym code EPSG:25832 is also working)
- EPSG:3045 ETRS89/ETRS-TM33
- EPSG:3046 ETRS89/ETRS-TM34
- EPSG:3047 ETRS89/ETRS-TM35
- EPSG:3059 LKS92/Latvia TM
- EPSG:3301 Estonian Coordinate System of 1997
- EPSG:3346 LKS94/Lithuania TM
- EPSG:3785 Web (pseudo) Mercator (synonym code EPSG:3857 works but is deprecated. Synonym non-offical google code EPSG:900913 does NOT work.)
See the GetCapabilities output of the WMS for an authoritative list. Performance should be best for EPSG:3035, as no re-projection is required in this case.
To learn more about the European Geodetic datum please visit http://georepository.com/datum_6258/European-Terrestrial-Reference-System-1989.html.
To learn more about Geographical datums in general please visit http://en.wikipedia.org/wiki/Geographic_datum.
The vertical reference in this project is the EVRF2007. All heights and depths are given in meters above sea level, i.e. depths feature negative values. The reference level is within 30cm of the Mean Sea Levels in the Baltic.
BSHC has an ongoing workgroup for harmonizing the chart datums in the Baltic region, preparing suggestions on how to change from a number of different vertical references to a reference tied to the geodetic references.