ELEMENTS OF THE NATIONAL SPATIAL REFERENCE SYSTEM

Transcription

1 Dave Doyle NGS Chief Geodetic Surveyor ELEMENTS OF THE NATIONAL SPATIAL REFERENCE SYSTEM ESRI SURVEY SUMMIT San Diego, CA June 17, 2007 ftp://ftp.ngs.noaa.gov/dist/daved/esri

2 1807 President Thomas Jefferson signs legislation establishing the Survey of the Coast

3 Ferdinand Hassler ( )

4 Our Positioning History What s In a Name? Survey of the Coast Coast Survey US Coast and Geodetic Survey National Ocean Service National Geodetic Survey (NOS geodetic functions)

5 Bilby Tower used from

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8 Global Satellite Triangulation Network

9 Positioning the Washington Monument

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12 GEODETIC CONTROL THE REALIZATION OF A DATUM NETWORK OF MONUMENTED POINTS PRECISELY MEASURED IN ACCORDANCE WITH STANDARD PROCEDURES MEET ACCURACY SPECIFICATIONS ADJUSTED TO TIE TOGETHER DOCUMENTED FOR MULTIPLE USE

13 National Spatial Reference System (NSRS) Consistent National Coordinate System Latitude Longitude Height Scale Gravity Orientation and how these values change with time

14 National Spatial Reference System (NSRS) U.S.HORIZONTAL DATUMS BESSEL COORDINATES ( ) NEW ENGLAND DATUM ( ) U.S. STANDARD DATUM ( ) ALASKA DATUMS (14 Different ) PUERTO RICO DATUM ( ) NORTH AMERICAN DATUM ( ) NORTH AMERICAN DATUM 1927 ( ) OLD HAWAIIAN DATUM ( ) NORTH AMERICAN DATUM 1983 (1983 PRESENT)

15 National Spatial Reference System (NSRS) U.S.VERTICAL DATUMS FIRST GENERAL ADJUSTMENT/SANDY HOOK DATUM (1899) SECOND GENERAL ADJUSTMENT (1903) THIRD GENERAL ADJUSTMENT (1907) FOURTH GENERAL ADJUSTMENT (1914) SEA LEVEL DATUM 1929 NATIONAL GEODETIC VERTICAL DATUM 1929 NORTH AMERICAN VERTICAL DATUM 1988 AMERICAN SAMOA VERTICAL DATUM 2002 PUERTO RICO VERTICAL DATUM 2002 NORTHERN MARIANAS VERTICAL DATUM 2003 GUAM VERTICAL DATUM 2004

16 NSRS COMPONENTS National Shoreline Consistent, accurate, and up-to-date Networks of geodetic control points Permanently marked passive survey monuments National and Cooperative CORS A network of GPS Continuously Operating Reference Stations Models and Tools Models of geophysical effects on spatial measurements e.g., NADCON, INVERSE, SPCS83, UTMS, FORWARD Standards & Guidelines Facilitate the development, sharing, and use of geospatial data

17 NATIONAL SPATIAL REFERENCE SYSTEM ACCURATE -- cm accuracy on a global scale MULTIPURPOSE -- Supports Geodesy, Geophysics, Land Surveying, Navigation, Mapping, Charting and GIS activities ACTIVE -- Accessible through Continuously Operating Reference Stations (CORS) and derived products INTEGRATED -- Related to International services and standards (e.g. International Earth Rotation and Reference Systems Service, International GNSS Service etc.)

18 NATIONAL SPATIAL REFERENCE SYSTEM North American Datum of 1983 (NAD 83) North American Vertical Datum of 1988 (NAVD 88) First civilian datums designed to be consistent with space-based observations (GPS) First civilian datums to be best-fitting globally not locally First geodetic reference systems to be fully automated First geodetic reference systems to be available free from WWW Only reference system to freely integrate data from outside sources

19 NSRS Coordinate Systems Latitude & Longitude State Plane Coordinates UTM Coordinates U.S. National Grid Earth-Centered Earth-Fixed NAD 83 NAD 27 NAVD 88 NGVD 29 ITRF00

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21 UNITED STATES ELLIPSOID DEFINITIONS N GEODETIC REFERENCE SYSTEM (GRS 80) (1986 Present) CLARKE b a = 6,378,137 BESSEL m 1/f = International standard (1879 (1851 adopted 1986) 1879) by IAG/IUGG/NGS a = 6,377, ,378,206.4 m m 1/f = Best Best fit East fit North Coast America of U.S. a WORLD GEODETIC SYSTEM (WGS 84) (1987 Present) a = 6,378,137 m 1/f = Defined for GPS by U.S. DoD a = Semi major axis b = Semi minor axis f = a-b = Flattening a S

22 ELLIPSOID - GEOID RELATIONSHIP H = Orthometric Height (NAVD 88) h = Ellipsoidal Height (NAD 83 NSRS 2007) N = Geoid Height (GEOID 03) H = h N H h Geoid N GEOID03 Ellipsoid GRS80

23 GEOID90 Various NGS Geoid models Earliest model gravimetric only GEOID93 Another early gravimetric geoid GEOID96 GEOID99 GEOID03 First hybrid geoid CONUS only Underlain by G96SSS gravimetric model Accuracy ~ 11.6 cm (95%) Still fairly heavily used - CONUS Underlain by G99SSS gravimetric model Accuracy ~ 9.2 cm (95%) Models tie to NAD 83 everywhere hybrid in CONUS Underlain by the USGG2003 gravimetric model Accuracy ~ 4.8 cm (95%) GEOID06 Forthcoming this year. Available for Alaska already. Will tie to NAD 83 and NAVD 88/PRVD02/etc. Accuracy ~ 2 cm (?)

24 EARLY NAD 83 NETWORK PROBLEMS NOT GPSABLE POOR STATION ACCESSIBILITY IRREGULARLY SPACED POSITIONAL ACCURACY

25 HIGH ACCURACY REFERENCE NETWORKS (HARN) GPSABLE Clear Horizons for Satellite Signal Acquisition EASY ACCESSIBILITY Few Special Vehicle or Property Entrance Requirements REGULARLY SPACED Always within Km HIGH ACCURACY A-Order (5 mm + 1:10,000,000) (3 5.5 hr sessions) B-Order (8mm + 1:1,000,000) (2 5.5 hr sessions)

26 FEDERAL AND COOPERATIVE BASE NETWORKS (FBN/CBN) MORE STATE PARTNERSHIPS REMOVE DISTORTIONS IN EARLY HARNS (3-10 CM) ENSURE CONNETIONS TO CORS IMPROVE ELLIPSOID HEIGHT ACCURACY (Not worse than 2 cm)

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28 CONTINUOUSLY OPERATING REFERENCE STATIONS (CORS) Installed and Operated by various Federal-State-local Agencies NOAA/National Geodetic Survey NOAA/OAR Global Systems Division U.S. Coast Guard - DGPS/NDGPS Corps of Engineers - DGPS FAA - WAAS/LAAS State DOTs County and City Academia Private Companies

29 CONTINUOUSLY OPERATING REFERENCE STATIONS (CORS) Dual-Frequency Antennas and Receivers Allen-Osborne Ashtech / Thales Leica Topcon Trimble

30 CONTINUOUSLY OPERATING REFERENCE STATIONS (CORS) NGS PROVIDES Reference Site Survey Monumentation Horizontal and Vertical NSRS Connections NAD 83 and ITRF00 Coordinates Network Data Collection - Hourly & Daily Daily 3D Network Integrity Adjustment Public Data Distribution - Internet 13 Year On-Line Data Holding

31 The National Geodetic Survey Ten Year Plan: Mission, Vision and Strategy

32 Ten-Year Milestones (2017) 1) NGS will compute a pole-to-equator, Alaskato-Newfoundland geoid model, preferably in conjunction with Mexico and Canada as well as other interested governments, with an accuracy of 1 cm in as many locations as possible 2) NGS redefines the vertical datum based on GNSS and a gravimetric geoid 3) NGS redefines the national horizontal datum to remove disagreements with the ITRF

33 GOOD COORDINATION BEGINS WITH GOOD COORDINATES GEOGRAPHY WITHOUT GEODESY IS A FELONY