- Swedish grid
Swedish grid (in Swedish Rikets Nät, RT90) is the
coordinate system used for government maps inSweden .While
negative numbers could be used to represent all four "quarters" of the earth (NE, NW, SE, and SW hemispheres) standard application of RT90 is only useful for the Northern half of the Eastern hemisphere where numbers are positive. The coordinate system is based on metric measures rooting from the crossing of thePrime Meridian and theEquator at 0,0. The Central Meridian used to be based on a meridian located at the old observatory in Stockholm, but today it is based on the Prime Meridian at Greenwich. The numbering systems first number represents the largest distance, followed by what can be seen as decimals. As such, X 65 is located half way between X 6 and X 7.The coordinate grid is specified using two numbers, confusingly named X and Y but having inverted positions from mathematical
graphs . X being the north - south axis and y the east - west axis.Example:E1317000 N6620000 (or Y=1317000 X=6620000) denotes a position 183 km (1317km-1500 km) west of the Central Meridian and 6620 km north of the Equator, which happens to be somewhere near the town center of
Arvika .RT90 Map Projection Parameters
References
* [http://www.lantmateriet.se/templates/LMV_Page.aspx?id=4766&lang=EN Two-dimensional systems: RT 90] Lantmäteriet (Swedish Land Survey).
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