The Swedish grid (in
Swedish
Swedish or ' may refer to:
Anything from or related to Sweden, a country in Northern Europe. Or, specifically:
* Swedish language, a North Germanic language spoken primarily in Sweden and Finland
** Swedish alphabet, the official alphabet used by ...
Rikets Nät, RT 90) is a
coordinate system that was previously used for government maps in
Sweden. RT 90 is a slightly modified version of the RT 38 from 1938. RT 90 has been replaced with SWEREF 99 as the official Swedish spatial reference system.
While the system could be used with
negative numbers
In mathematics, a negative number represents an opposite. In the real number system, a negative number is a number that is less than zero. Negative numbers are often used to represent the magnitude of a loss or deficiency. A debt that is owed ma ...
to represent all four "quarters" of the earth (NE, NW, SE, and SW hemispheres), the standard application of RT 90 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 the
Prime Meridian
A prime meridian is an arbitrary meridian (a line of longitude) in a geographic coordinate system at which longitude is defined to be 0°. Together, a prime meridian and its anti-meridian (the 180th meridian in a 360°-system) form a great ...
and the
Equator 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 system's first digit represents the largest distance, followed by what can be seen as fractional decimal digits (though without an explicit decimal point). Therefore, X 65 is located halfway between X 6 and X 7.
The coordinate grid is specified using two numbers, named X and Y, X being the south–north axis and Y the west–east axis. Two seven-digit numbers are sufficient to specify a location with a one m resolution.
Example:
X=6620000 Y=1317000 (X is the northing and Y is the easting) denotes a position 6620 km north of the Equator and -183 km (1317 km-1500 km) west of the Central Meridian, which happens to be somewhere near the town center of
Arvika.
RT90 Map Projection Parameters
References
Three-dimensional systems: SWEREF 99Lantmäteriet (Swedish Land Survey).
Two-dimensional systems: RT 90Lantmäteriet (Swedish Land Survey).
Geography of Sweden
Geographic coordinate systems
{{Sweden-geo-stub