6

I have a shapefile of Finland in WGS84 (EPSG:4326), that I would like to convert to projected coordinate system, most commonly used in Finland.

But, here is my confusion: I have found that from 2005, topographic maps should be in EUREF-FIN CS, as ETRS89 realization in Finland http://www.kolumbus.fi/eino.uikkanen/geodocsgb/ficoords.htm

But, here they also list ETRS-TM35FIN to use for country wide displays. So, what is the difference between EUREF-FIN CS and ETRS-TM35FIN?

In ArcGIS, I can find both of them, under different WKID code:

  • WKID: 3067: EUREF_FIN_TM35FIN
  • WKID: 5048: ETRS_1989_TM35FIN_NE

Checking using EPSG codes (https://epsg.io/), the same WKID codes represent the same CS name, but with switched Northing and Easting! (why would anyone do that?!)

  • EPSG: 3067: ETRS89 / TM35FIN(E,N)
  • EPSG: 5048: ETRS89 / TM35FIN(N,E)

SYKE institute provides free open data in ETRS-TM35FIN (EPSG:3067), which again mixes the name (ETRS) with EPSG for EUREF_FIN_TM35FIN.

Well, what is proper coordinate system to use in Finland? and how is it specified in ArcGIS/proj4 library?

Improve this question

2 Answers 2

Reset to default
8

As you found, EUREF-FIN is a realization of ETRS89 in Finland.

Some countries, when displaying coordinates or transmitting data, use the convention northing, easting order while other countries use easting, northing order. Most GIS software wants easting, northing so the EPSG registry (http://www.epsg-registry.org NOT epsg.io) often has both versions depending on what's been requested to add to the registry.

In ArcGIS, on the Coordinate Systems tab in ArcMap or the Coordinate System section in ArcGIS Pro, then browse the folders for Projected Coordinate Systems, National Grids, Finland.

As @Hornbydd said, you should set a geographic (datum) transformation, but this particular one has zeroes for the parameters so won't change the coordinate values.

[edit: fixed link]

Improve this answer
3
  • thank you for your answer. But, why not to use epsg.io? The link to wwww.epsg-registry.org is broken. Can you provide updated one?
    – maycca
    Commented Oct 2, 2019 at 6:27
  • Use only three "w" letters in the address. That is the official registry, epsg.io is using data from the epsg registry for its services but sometimes they have errors or they use old data.
    – user30184
    Commented Oct 2, 2019 at 7:01
  • 3
    ETRS89 based TM zones are usually following the N-E coordinate axis order. See for example epsg-registry.org/export.htm?wkt=urn:ogc:def:crs:EPSG::3049. WGS 84 based UTM zones are usually E-N epsg-registry.org/export.htm?wkt=urn:ogc:def:crs:EPSG::32637. The EPSG:3067 system that is recommended by the Finnish authorities is an exception because it is based on ETRS89 but is still using E-N axis order.
    – user30184
    Commented Oct 2, 2019 at 7:15
6

I can't answer why they would flip N/E but if I had got data (e.g. OSM) in WGS84 and wanted to projected it in ArcMap into EUREF_FIN_TM35FIN (WKID: 3067) then I would have set the transformation as shown below. According to this ESRI documentation the transformation has a WKID of 108227.

Not sure my answer helps?

Screenshot

Improve this answer
1
  • OK, so the corrrect WKID in ArcGIS is 3067, not the 5048? Can you please specify this in your answer as well? Thank you @hornbydd
    – maycca
    Commented Oct 2, 2019 at 6:07

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.