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Transcript of NGA PowerPoint Presentation - Cloud Object Storage | … · mensuration software, and Application...
Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCYApproved for public release #05-328.
LEADSLEADSThe Essential Elements of a 3-D Geographic CoordinateThe Essential Elements of a 3-D Geographic Coordinate
John W. Dix13 September 2005ESRI Homeland Security GIS Summit - Denver, [email protected]
John W. Dix13 September 2005ESRI Homeland Security GIS Summit - Denver, [email protected]
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NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Know the Earth…Show the WayApproved for public release #05-328.
LEADSOverview
LEADS is a framework for reporting the LEADS is a framework for reporting the essential elements of a three dimensional essential elements of a three dimensional (3(3--D) geographic coordinateD) geographic coordinate
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NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Know the Earth…Show the WayApproved for public release #05-328.
LEADSBackground
• Global Positioning System (GPS) provides a worldwide network for determining precise geodetic positions
• GPS geographic coordinates based on the WGS-84 ellipsoid are global, standardized, precise, and reliable
• GIS provide geographic coordinates in a variety of formats which may not be referenced to a datum and lack information about source and accuracy of a coordinate
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NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Know the Earth…Show the WayApproved for public release #05-328.
LEADSComparison of GPS and GIS
LEADSComparison of GPS and GIS
GPS GIS
• Geocentric• Absolute Positioning• Coherent Network• Precise• WGS-84 Datum• Worldwide
• Image Space• Object Characterization• Various Implementations• Inconsistent Accuracy• Various Datums• Worldwide
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NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Know the Earth…Show the WayApproved for public release #05-328.
LEADSThe 5 Elements of LEADS
• L: Latitude and Longitude• E: Elevation • A: Accuracy• D: Datum• S: Source
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NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Know the Earth…Show the WayApproved for public release #05-328.
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NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Know the Earth…Show the WayApproved for public release #05-328.
LEADSHeight Above Ellipsoid
&Mean Sea Level
Surface of Earth
Mean Sea Level
WGS-84Ellipsoid
Elev
atio
nA
bove
Mea
n Se
a Le
vel
HeightAbove Ellipsoid
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NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Know the Earth…Show the WayApproved for public release #05-328.
9
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Know the Earth…Show the WayApproved for public release #05-328.
LEADSThe 5 Elements of LEADS
• L: Latitude and Longitude• E: Elevation
• Height Above Ellipsoid (GPS)• Mean Sea Level (MSL)
• A: Accuracy• Horizontal• Vertical
• D: Datum• WGS-84 Ellipsoid• North American Datum 1983• Other
• S: Source• GPS Receiver• Paper map or chart series• Geographic Information System• Other
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NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Know the Earth…Show the WayApproved for public release #05-328.
LEADSValue Added
• Provides producers and users a common framework for transferring and assessing geographic coordinates from different sources
• Allows users to correlate geographic coordinates from various sources, such as GIS, paper maps and charts, and GPS receivers
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NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Know the Earth…Show the WayApproved for public release #05-328.
LEADSProcess
StandardizedProduction
Process
SystemDesign
&Development
LEADS
• Standards Based> Systems
Engineering> Application
Interfaces
Procedures&
Training
ProcessedGeographicCoordinates
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NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Know the Earth…Show the WayApproved for public release #05-328.
LEADSSummary
• LEADS defines the minimum set of data elements required to accurately characterize a geodetic coordinate
• LEADS does not satisfy every need, but is a simplified format for describing the most important elements of a geographic coordinate
• LEADS concept can be broadly applied in military, scientific, and technical applications
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NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Know the Earth…Show the WayApproved for public release #05-328.
LEADS Recommendations
• Know the heritage of the coordinate(s) you are using• Build quality into the process instead of inspecting for
quality after production (W. E. Deming)• Define community best practices for determining,
communicating, integrating, and displaying geographic coordinates
• Develop Graphical User Interfaces, applications, mensuration software, and Application Program Interfaces (API) that implement best practices
• Use display format for geographic coordinates that is readily understood– Degrees/Minutes/Seconds (D/M/S) versus Decimal
degrees (D.dddddd)• Adopt best practices in software and system engineering
that display geographic coordinate at a level of precision consistent with the accuracy of the source from which the coordinate is derived
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NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Know the Earth…Show the WayApproved for public release #05-328.
LEADS Conclusion
Geospatial information community would benefit from a standard methodology for correlating geographic coordinates from GIS, imagery, and paper maps and charts with geographic coordinates from GPS receivers.
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NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Know the Earth…Show the WayApproved for public release #05-328.
LEADSTechnical Details Worth Remembering
• Image resolution is not an indicator of geopositional accuracy– One meter pixels do not mean one meter
geopositional accuracy• Adding decimal precision to an inaccurate
coordinate does not make it more precise and dilutes its integrity
• Measuring a coordinate to nearest 0.001 seconds of arc (1.2 inches), is rarely possible, leaves the impression that a coordinate is precise, and complicates correlating coordinates from multiple sources
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NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Know the Earth…Show the WayApproved for public release #05-328.
LEADSTechnical Details Worth Remembering
At the equator:
• One minute of arc equals one nautical mile (~6080 feet)
• One second of arc equals approximately 101 feet:– 0.01 arc seconds = 1 foot– 0.001 arc seconds = 0.1 feet (1.2 inches)
• One degree is approximately 364,800 feet:– 10-5 degrees ~ 3.6 feet– 10-6 degrees ~ 4 inches– 10-7 degrees ~ 1/2 inch
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NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Know the Earth…Show the WayApproved for public release #05-328.
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Know the Earth…Show the Way