The USNG is an alpha-numeric reference system that overlays the UTM coordinate system. A USNG spatial address is broken down into three parts, the; - Grid Zone Designation; for a world-wide unique address. - 100,000-meter Square Identification; for regional areas. - Grid Coordinates; for local areas.
4 digits - 2306 - locates a point with a precision of 1,000-meters (a neighborhood size area). 6 digits - 234064 - locates a point with a precision of 100-meters (a soccer field size area). 8 digits - 23480647 - locates a point with a precision of 10-meters (the size of a modest home). 10 digits - 2348306479 - locates a point with a precision of 1-meter (within a parking spot).
To review, we can see a complete US National Grid spatial address contains three parts as we drill down to a unique location, 18S UJ 23480647 - Grid Zone Designation (i.e. 18S). - 100,000-meter Square Identification (i.e. UJ ). - Grid coordinates of some even number of digits ranging from 2 to 10 (i.e. 23480647 In this case, eight digits identify a place of about the size of a modest home.). You always read right, then up when plotting coordinates.
A spatial address is customarily written as a single string of values. Note how the horizontal datum (NAD 83) has been included: USNG: 18SUJ23480647 (NAD 83)
Floridadisaster.org --------------------------------------------------------------- In an effort to standardize maps in Florida for both emergency and other operations, the State Fire Marshal, as the coordinating agency for search and rescue under the State Comprehensive Emergency Management Plan, and the Division of Emergency Management are embarking on a program to adopt the US National Grid (USNG) as the standard in Florida. This project will ensure a uniform grid mapping system across cities and counties in Florida, and will match the system used by the National Guard, the US Coast Guard and the US military when they are deployed into our state.
Floridas unique geography of miles of coastlines, multiple river corridors, and large watersheds make the use of the common Township/Range/Section grid (PLSS) all but impossible except for a handful of inland counties. As the grid approaches wetlands, river corridors and the coast line, sections become irregular in shape and can be significantly larger than the typical square mile, which is too large to accommodate the needs of ground crews.
Adoption of a national grid system has been identified as critical in a number of after action reports, investigations and studies dating as far back as Hurricane Andrew. FEMA, DHS, the National GeoSpatial Intelligence Agency, and the Federal Geographic Data Committee all promote the adoption of the USNG.
Grid cell values are unique and sequentially numbered.
A note about data scale:
Scale is an important factor in data usage. Certain scale datasets are not suitable for some project, analysis, or modeling purposes. Please be sure you are using the best available data.
1:24000 scale datasets are recommended for projects that are at the county level. 1:24000 data should NOT be used for high accuracy base mapping such as property parcel boundaries. 1:100000 scale datasets are recommended for projects that are at the multi-county or regional level. 1:125000 scale datasets are recommended for projects that are at the regional or state level or larger.
Vector datasets with no defined scale or accuracy should be considered suspect. Make sure you are familiar with your data before using it for projects or analysis. Every effort has been made to supply the user with data documentation. For additional information, see the References section and the Data Source Contact section of this documentation. For more information regarding scale and accuracy, see our webpage at: <http://geoplan.ufl.edu/education.html>
Guidelines for Building US National Grid Polygons with ArcGIS <http://floridadisaster.org/gis/usng/Documents/build_usng_polygons.pdf>
For more information on field calculations please see Guidelines for Building US National Grid Polygons with ArcGIS <http://floridadisaster.org/gis/usng/Documents/build_usng_polygons.pdf>
Added fields: DESCRIPT, FGDLAQDATE, and AUTOID.
Calculated the AUTOID field as follows; [FID] + 1
Calculated DESCRIPT based on LABEL.
Calculated FGDLAQDATE based on the date the data was downloaded from the source.