United States National Grid United States National Grid (USNG) in Florida(USNG) in Florida

Erika Pittman, GIS Analyst850-413-9906erika.pittman@em.myflorida.com

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United States National Grid

• Lessons learned have taught us that standardized grids are needed for positional reporting.

• As far back as Hurricane Andrew, problems were recognized for emergency managers...

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Florida Adopts the USNG• USNG was officially adopted by the FFCA• FDEM to adopt the USNG in the States CEMP• Updates of GIS/Maps in the 11 Regional

Evacuation Studies will include USNG grids• Florida Fire College, Florida Fire Chiefs

Association, FL National Guard to develop curriculum and instructor manuals

• FFC will be incorporating an intro module in the Firefighter II curriculum

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What’s wrong with current systems?

We already have…

– Latitude/Longitude

–Township/Range/Section

– Street Address and Zip

– UTM

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Latitude/Longitude

Multiple formats are confusing

DD -85.990151, 30.272240

DM -85 59.409089, 30.16.334386

DMS 85 59’24.545”W, 30 16’20.063”N

All the same location!!!

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How far is a second anyway?

What is the distance from….

85 59’24.545”W, 30 16’20.063”N

To here….

85 59’26.292”W, 30 16’14.546”N

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Township/Range/Section

Township/Range/Section grid from the Public Lands Survey System is an important and good system…

– basis of land ownership records

– been in use for over 180 years

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Township/Range/Section

• But a perfect section really doesn’t exist

• irregular in coastal areas

• too large to meet needs of ground crews

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Street Address and Zip

• Problematic due to…

– rural routes

– post office boxes

–House numbers missing or obscured

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• What do you do when the SIGNS are gone?

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• What do you do when the ROADS are gone?

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Universal Transverse Mercator• Measuring distances and obtaining

positional accuracy has always been a challenge.

• European allies demonstrated the utility of grid-based conformal maps mapping their territory during the interwar period .

Abbreviated as “UTM”

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• The Universal Transverse Mercator (UTM) coordinate system is a grid-based method of specifying locations on the surface of the Earth that is a practical application of a 2-dimensional rectangular coordinate system . It is used to identify locations on the earth, but differs from the traditional method of latitude and longitude in several respects.

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• The UTM system is not a single map projection. The system instead employs a series of sixty zones, each of which is based on a specifically defined secant transverse Mercator projection.

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• Developed by the United States Army Corps of Engineers in the 1940s

• A position on the Earth is referenced in the UTM system by the UTM zone, and the easting and northing coordinate pair. The easting is the projected distance of the position from the central meridian, while the northing is the projected distance of the point from the equator.

16R 766000 3364820

UTM

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• is the geocoordinate standard used by North Atlantic Treaty Organization (NATO) for locating points on the earth.

• is derived from the UTM grid system, but uses a different labeling convention.

Abbreviated as “MGRS”

Military Grid Reference System

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• Uses a 2 to 10 character geocode– 2 digits implies precision of 10 km

– 10 digits implies precision of 1 m

– 100,000 m grids truncated and replaced with alpha-numeric grid

16R GU 66000 64820

MGRS

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• It resembles the Military Grid Reference System (MGRS). When the WGS84 datum is used, USNG and MGRS coordinates are practically identical.

16R GU 66000 64820

Abbreviated as “USNG”

United States National Grid

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USNG• it has the advantage of being easily plotted

on USGS topographic maps by using a simple "right and then up" method instead of having to plot from right to left when using latitude and longitude in the Western Hemisphere. The coordinates are also easily translated to distance since they are in meters. Thus the distance between two coordinates can quickly be determined in the field.

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16R GU 66000 64820

How to read USNG

100,000 Meter Grid – identification for regional areas

Grid Coordinates – Easting and Northing position

Grid Zone Designation – for a world-wide unique address, identifies the longitude zone number and the latitude band letter

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16R GU 66000 64820

16R 17R

Truncate for locality

• just like you don’t have to dial an area code to make a local call…• all Florida locations will be 16R or 17R

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16R GU 66000 64820

16R 17R

Truncate for locality

• 100,000 meter zone designation may be dropped when working locally

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Truncate for less precision…

Locates within 1000 meters66 64

6600 6482 Locates within 10 meters

660 648 Locates within 100 meters

66000 64820 Locates within 1 meter

16R GU 66000 64820

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USNG

• Easily scaleable

• Pin-point and cell

based locational reporting

• “Grid within a Grid”

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Global Positioning Systems

• I have GPS……..why do I need to care about any of this?

– USNG can be used with GPS

– GPS supplements USNG

– USNG will work when your GPS won’t

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USNG and GPS

• Most GPS units explicitly support USNG as an option for units

• If you choose USNG, you must also choose NAD 83 as your datum (or technically, you haven’t chosen USNG)

• You may also choose MGRS with NAD 83 to be the functional equivalent of USNG

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USNG Sample Maps

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Support for USNG• http://www.floridadisaster.org/gis/usng

– tools and instructions for GIS staff

• FDEM’s Incident Mapper– simple Google Maps mashup with USNG tools

• FDEP’s MapDirect– complex mapping tools with USNG support

• “Geo”PDF’s– new PDF formats have GIS capabilities,

including USNG support

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Support for USNG

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FDEP MapDirect

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USNG in ArcGIS 9.1• USNG National Grid Tools

Repackaging of…

–Military Analyst

–Product line tool set (PLTS)

• USNG Locational Toolbar

Available from ArcScripts

–Less complicated, easier to use

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USNG in ArcGIS 9.2/9.3• Integrated…

– Go to X,Y Tool

– Identify

–Graticules

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Military Analyst in ArcGIS 9.2/9.3USNG coordinates may easily be added to a feature class.

NAR-C isproper NAD 83 choice - “North American Reference CONUS”

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Military Analyst in ArcGIS 9.2/9.3USNG coordinates added to a feature class.

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Map Books in ArcGIS 9.2/9.3

• DS Map Book (free extension to ArcMap

• Produce 4,000 m x 5,000 8.5” x 11” 1:24,000 scale maps

• Style guide, templates and video from Delta State University linked from http://www.floridadisaster.org/gis/USNG/index.htm#mapbooks

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• Guidance for building and using grids.

• Style Guide for using USNG in ArcGIS

• Downloadable grids

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Map Books in ArcGIS 9.2/9.3Sample county map book easily create in ArcMap

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Map Books in ArcGIS 9.2/93

• If you have a county wide map book (with USNG or not), please let us know for inclusion on our website

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USNG in Other Applications• Delorme’s XMAP

• GeoPDF

• Dolph Maps

• New USGS Quad Maps

• The National Map

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Florida Geographic Data Library• To host 1,000

meter and 100 meter grids for each Florida county

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More information…http://www.floridadisaster.org/gis/usng

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Erika Pittman

Florida Division of Emergency Management

850-413-9906

erika.pittman@em.myflorida.com