Kuopio coordinate system

History of the plane coordinate system

Previously, Kuopio’s own plane coordinate system was used within the City of Kuopio. It was introduced before the National Coordinate System (NCS). The coordination system was based on the old state system (vvj). National level coordinate systems were discontinued in Kuopio on 1 November 2012. 

Vertical coordinate reference system 

The conversion of the vertical coordinate reference system became necessary due to the isostatic uplift. Since the the implementation of the N43 vertical coordinate reference system, the ground in the centre of kuopio has risen approximately 382 mm. The difference between the N60 vertical coordinate reference system used in the area of joint municipal authorities, with the difference to the current vertical coordinate reference system is 29–30 cm. 

The heights according to the N43 elevation model were changed to the N60 elevation system with a standard 102 mm correction, in which case N60 = N43 + 102 mm. Regional corrections were defined on the basis of precision measurements, with the help of which the height data of the old N60 height system could be converted to the N2000 height system, which is also used by the City’s terrain survey in its measurements. 

The map shows the impact of the post-glacial rebound in the Kuopio area over a period of 40 years (N60->N2000). 

Differences in the height system by district (pdf) 

The ETRS-GK27 coordinate system is best identified by the eastern coordinates. It starts with 27 and has 8 digits before decimal places. Kuopio had only five digits in its own coordinate system and seven digits in the KKJ. The northern coordinates of the ETRS-GK27 coordinate system have seven digits, as well as the KKJ, but the Kuopio coordinate system had only five digits. The ETRS-TM35 coordinate system is also used nationally, for example in basic maps. They have six digits in the eastern coordinates and seven in the northern coordinates. 

Separating height systems is more difficult or practically impossible from numerical values, as heights change only in between 26 and 38 cm. When using elevation figures, it is important to mark the elevation system used in the document or material metadata. 

Below is an example of the same point in different coordinate systems: 

Plane coordinates N (North) E (East)

• ETRS-GK27 6973890.234 27535622.747
  – ETRS-TM35FIN 6971100.678 535608.498
  – KKJ 3-sidewalk 6974022.360 3535794.285
  – Kuopio (vvj) 74020.913 35795.357
  – ETRS-Lan/Lon 62° 52′ 05.60234” 27° 41′ 59.46903”

Vertical coordinate reference system height (m)
– N2000 91,16
– N60 90.88
– N43 90.78