leads
Know the Earth…Show the Way
LEADS The Essential Elements of a 3-D Geographic Coordinate
John W. Dix 13 September 2005 ESRI Homeland Security GIS Summit - Denver, CO [email protected] Approved for public release #05-328.
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS Overview
LEADS is a framework for reporting the essential elements of a three dimensional (3-D) geographic coordinate
Approved for public release #05-328.
2 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS Background
• 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 Approved for public release #05-328.
3 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS Comparison of GPS and GIS
GPS
GIS
• Geocentric
• Image Space
• Absolute Positioning
• Object Characterization
• Coherent Network
• Various Implementations
• Precise
• Inconsistent Accuracy
• WGS-84 Datum
• Various Datums
• Worldwide
• Worldwide
Approved for public release #05-328.
4 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS The 5 Elements of LEADS
• • • • •
L: E: A: D: S:
Latitude and Longitude Elevation Accuracy Datum Source
Approved for public release #05-328.
5 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Approved for public release #05-328.
6 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS Height Above Ellipsoid & Mean Sea Level
WGS-84 Ellipsoid Height Above Ellipsoid
Approved for public release #05-328.
Mean Sea Level
Elevation Above Mean Sea Level
Surface of Earth
7 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Approved for public release #05-328.
8 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS The 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
Approved for public release #05-328.
9 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS Value 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
Approved for public release #05-328.
10 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS Process
System Design & Development
• Standards Based > Systems Engineering > Application Interfaces Approved for public release #05-328.
Standardized Production Process
Procedures & Training
LEADS
Processed Geographic Coordinates 11 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS Summary
• 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
Approved for public release #05-328.
12 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
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
Approved for public release #05-328.
13 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
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.
Approved for public release #05-328.
14 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS Technical 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 Approved for public release #05-328.
15 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS Technical 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 Approved for public release #05-328.
16 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Know the Earth…Show the Way
Approved for public release #05-328.
17 Know the Earth…Show the Way
LEADS The Essential Elements of a 3-D Geographic Coordinate
John W. Dix 13 September 2005 ESRI Homeland Security GIS Summit - Denver, CO [email protected] Approved for public release #05-328.
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS Overview
LEADS is a framework for reporting the essential elements of a three dimensional (3-D) geographic coordinate
Approved for public release #05-328.
2 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS Background
• 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 Approved for public release #05-328.
3 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS Comparison of GPS and GIS
GPS
GIS
• Geocentric
• Image Space
• Absolute Positioning
• Object Characterization
• Coherent Network
• Various Implementations
• Precise
• Inconsistent Accuracy
• WGS-84 Datum
• Various Datums
• Worldwide
• Worldwide
Approved for public release #05-328.
4 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS The 5 Elements of LEADS
• • • • •
L: E: A: D: S:
Latitude and Longitude Elevation Accuracy Datum Source
Approved for public release #05-328.
5 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Approved for public release #05-328.
6 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS Height Above Ellipsoid & Mean Sea Level
WGS-84 Ellipsoid Height Above Ellipsoid
Approved for public release #05-328.
Mean Sea Level
Elevation Above Mean Sea Level
Surface of Earth
7 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Approved for public release #05-328.
8 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS The 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
Approved for public release #05-328.
9 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS Value 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
Approved for public release #05-328.
10 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS Process
System Design & Development
• Standards Based > Systems Engineering > Application Interfaces Approved for public release #05-328.
Standardized Production Process
Procedures & Training
LEADS
Processed Geographic Coordinates 11 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS Summary
• 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
Approved for public release #05-328.
12 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
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
Approved for public release #05-328.
13 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
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.
Approved for public release #05-328.
14 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS Technical 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 Approved for public release #05-328.
15 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
LEADS Technical 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 Approved for public release #05-328.
16 Know the Earth…Show the Way
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY
Know the Earth…Show the Way
Approved for public release #05-328.
17 Know the Earth…Show the Way
