The State Plane Coordinate System (SPS or SPCS) is a set of more than 100 geographic coordinate systems designed for specific regions of the United States. Each state contains one or more state plane zones, the boundaries of which usually follow county lines. The system is widely used for geographic data by state and local governments. Its popularity is due to at least two factors. First, it uses a simple cartesian coordinate system to specify locations rather than a more complex spherical coordinate system (the geographic coordinate system of latitude and longitude). By thus ignoring the curvature of the Earth, "plane surveying" methods can be used, speeding up and simplifying calculations. Second, the system is highly accurate within each zone. Outside a specific state plane zone accuracy rapidly declines, thus the system is not useful for regional or national mapping. In mathematics as applied to geometry, physics or engineering, a coordinate system is a system for assigning a tuple of numbers to each point in an n-dimensional space. ... Geographic data is about much more than electronic pictures of maps. ... Fig. ... A point plotted using the spherical coordinate system In Mathematics, the spherical coordinate system is a coordinate system for representing geometric figures in three dimensions using three coordinates, (ρ, φ, θ), where ρ represents the radial distance of a point from a fixed origin, φ represents the zenith angle from the positive z-axis and... Map of Earth showing lines of latitude (horizontally) and longitude (vertically), Eckert VI projection; large version (pdf, 1. ... Latitude, usually denoted symbolically by the Greek letter φ, gives the location of a place on Earth north or south of the Equator. ... Longitude, sometimes denoted by the Greek letter λ, describes the location of a place on Earth east or west of a north-south line called the Prime Meridian. ...

Each state plane zone is based on either a Transverse Mercator projection or a Lambert conformal conic projection. The choice between the two map projections is based on the shape of the state and its zones. States that are long in the east-west direction are typically divided into zones that are also long east-west. These zones use the Lambert conformal conic projection, because it is good at maintaining accuracy along an east-west axis. Zones that are long in the north-south direction use the Transverse Mercator projection because it is better at maintaining accuracy along a north-south axis. One part of one state, the panhandle of Alaska, uses the Oblique Mercator projection, since that region lies on a diagonal. // Transverse Mercator Projection A Transverse Mercator projection A Transverse Mercator projection is an adaptation of the Mercator projection. ... Hello ... The Mercator projection shows courses of constant bearing as straight lines. ...

History

The state plane coordinate system came into being during the 1930s. It has been revised several times since then. When computers began to be used for mapping and GIS, the state plane system's cartesian grid system and simplified calculations made spatial processing faster and spatial data easier to work with. A geographic information system (GIS) is a system for creating, storing, analyzing and managing spatial data and associated attributes. ...

Even though computer processing power has improved radically since the early days of GIS, the size of spatial datasets and the complexity of geoprocessing tasks being demanded of computers have also increased. Thus the state plane coordinate system is still useful.

Originally, the state plane coordinate systems were based on the North American Datum of 1927 (NAD27). Later, the more accurate North American Datum of 1983 (NAD83) became the standard (a datum is the way a coordinate system is linked to the physical Earth). More recently there has been an effort to increase the accuracy of the NAD83 datum using technology that was not available in 1983. These efforts are known as "High Accuracy Reference Network" (HARN) or "High Precision GPS Network" (HPGN). In addition, the basic unit of distance used is sometimes feet and sometimes meters. Thus a fully described coordinate system often looks something like: "Washington State Plane North, NAD83 HARN, feet". This information is needed in order to accurately transform data from one coordinate system to another. The North American Datum is the official reference ellipsoid used for the primary geodetic network in North America. ... It has been suggested that this article or section be merged with Geodetic system. ...

Problems

The main problem with the state plane coordinate system is that each zone uses a different coordinate system. This is not a major problem as long as one's needs are within the boundaries of a given state plane zone, as is the case with most county and city governments. However, the need to transform spatial data from one coordinate system to another can be burdensome. Sometimes a regional area of interest, such as a metropolitan area covering several counties, crosses a state plane zone boundary. The Seattle metropolitan area is an example of this. King County, which includes the City of Seattle, uses the "Washington State Plane North" coordinate system, while Pierce County, which includes the City of Tacoma, uses "Washington State Plane South". Thus any regional agency that wants to combine regional data from local governments has to transform at least some data into a common coordinate system. The Seattle metropolitan area includes the city of Seattle, Washington; King County, Washington; and several surrounding cities and counties in the Puget Sound area. ... King County redirects here; you may be looking for King County, Texas. ... Nickname: The Emerald City Location of Seattle in King County and Washington Coordinates: Country United States State Washington County King County Incorporated December 2 1869 Mayor Greg Nickels Area    - City 369. ... Pierce County is the second most populous county in the state of Washington. ... Old Town neighborhood in Tacoma, with Mount Rainier (Tahoma) in background Nickname: The City of Destiny Location of Tacoma in Pierce County and Washington State County Pierce Mayor Bill Baarsma (NP) Area    - City 162. ...

See also

• Public Land Survey System
• Universal Transverse Mercator coordinate system

The Public Land Survey System (PLSS) is a method used in the United States to survey and identify land parcels, particularly for titles and deeds of rural, wild or undeveloped land. ... The UTM Grid The Universal Transverse Mercator (UTM) projection system is a grid-based method of specifying locations on the surface of the Earth. ...

External links

• The State Plane Coordinate System, at vterrain.org
• National Geodetic Survey (NGS)