Standard for a U.S. National Grid
The objective of this standard is to create a more favorable environment for developing location-based services within the United States and to increase the interoperability of location services appliances with printed map products by establishing a nationally consistent grid reference system as the preferred grid for National Spatial Data Infrastructure (NSDI) applications. This standard defines the US National Grid. The U.S. National Grid is based on universally defined coordinate and grid systems and can, therefore, be easily extended for use world-wide as a universal grid reference system.
There are a number of coordinate reference systems that can be used either in location service appliances or on printed maps for the purpose of establishing a location. Within automated location service appliances, the conversion of coordinates based on one well-defined reference system to coordinates based on another can be both automatic and transparent to the user. These devices can support multiple coordinate reference systems with little difficulty. However, it is not easy for humans to work in multiple reference systems and humans cannot convert between systems without the aid of location service appliances, calculators, or conversion tables. Furthermore, it is difficult for humans to accurately determine a location coordinate from paper maps when latitude and longitude are used because they do not appear square on the flat map. As a consequence paper maps created for the general public frequently have a square reference grid that overlays the non-rectangular coordinate reference system. It is computationally difficult, labor intensive, and time consuming to convert the reference grid coordinate obtained from one printed map to another printed map with a different grid even when both grid reference systems are well defined. It can be impossible when proprietary grids are used. This situation greatly limits the ability of humans to use location service devices with traditional printed maps. Subsequently, location based services in this country have been limited to totally digital environments, restricting the number of uses and retarding the development of the location based service industry.
This standard seeks to improve the current situation by identifying a single nationally consistent, humanly facile grid reference system as the preferred U.S. National Grid (USNG) and promoting its use within the NSDI.
This standard defines a preferred U.S. National Grid (USNG) for mapping applications at scales of approximately 1:1,000,000 and larger. It defines how to present Universal Transverse Mercator (UTM) coordinates at various levels of precision. It specifies the use of those coordinates with the grid system defined by the Military Grid Reference System (MGRS). Additionally, it addresses specific presentation issues such as grid spacing. The UTM coordinate representation, the MGRS grid, and the specific grid presentation requirements together define the USNG. This standard is a process standard as defined by the Federal Geographic Data Committee (FGDC) Standards Reference Model. Specifically, it is a presentation process standard.
FGDC Standards Working Group
|Proposal||2000-05-03||FGDC Standards Working Group|
|Public review draft||2000-11||FGDC Standards Working Group|
|Comment adjudication log||2001-09-12||FGDC Standards Working Group|
|Final draft||2001-09||FGDC Standards Working Group|
For information and resources, visit www.fgdc.gov/usng
Obtain code for converting USNG values in software: National Geodetic Survey
Articles with information on the US National Grid:
- The United
States National Grid, Surveyor Magazine, September 2004, p.
Focuses on how to read a USNG coordinate. File size: 1.8Mb
- Geoaddress, Where Is
It?, Surveyor Magazine, November 2004, p. 30
Discusses the concept of USNG based geoaddresses. File size: 672Kb
- Introducing the
United States National Grid, ArcUser Magazine, July-September,
USNG educational poster (1.8Mb) produced by the Skagit County, WA GIS Office