DEVELOPMENT, IMPLEMENTATION AND FUTURE OF THE NATIONAL SPATIAL REFERENCE SYSTEM PROFESSIONAL LAND SURVEYORS OF OHIO TOLEDO FEBRUARY 11, 2000 David Doyle National Geodetic Survey

NATIONAL GEODETIC SURVEY INFORMATION CENTER (301) NATIONAL OCEAN SERVICE WEB SITE

INTERESTING WEB SITES GIS/GPS/RS Web Forum The On-Line Resource for Professional Land Surveyors NATIONAL OCEAN SERVICE

NATIONAL SPATIAL REFERENCE SYSTEM The National Spatial Reference System (NSRS) is that component of the National Spatial Data Infrastructure (NSDI) - [ which contains all geodetic control contained in the National Geodetic Survey (NGS) Data Base. This includes: A, B, First, Second and Third-Order horizontal and vertical control, Geoid models such as GEOID 99, precise GPS orbits and Continuously Operating Reference Stations (CORS), observed by NGS as well as data submitted by other Federal, State, and local agencies, Academic Institutions and the private sector NATIONAL OCEAN SERVICE

METADATA METADATA IS DATA ABOUT DATA DATUMS NAD 27, NAD 83(1986), NAD83 (199X), NGVD29,NAVD88 UNITS Meters, U.S. Survey Feet, International Feet, Chains, Rods, Pole ACCURACY A, B, 1st, 2nd, 3rd, 3cm, Scaled NATIONAL OCEAN SERVICE

THE ELLIPSOID b a a = Semi major axis b = Semi minor axis f = a-b = Flattening a N S NATIONAL OCEAN SERVICE

ELLIPSOID DEFINITIONS NATIONAL OCEAN SERVICE CLARKE 1866 a = 6,378,206.4 m 1/f = GEODETIC REFERENCE SYSTEM (GRS 80) a = 6,378,137 m 1/f = WORLD GEODETIC SYSTEM (WGS 84) a = 6,378,137 m 1/f = BESSEL 1841 a = 6,377, m 1/f =

ELLIPSOID - GEOID RELATIONSHIP H h Ellipsoid GRS80 H = Orthometric Height N Geoid GEOID99 H = h - N PERPENDICULAR TO ELLIPSOID PERPENDICULAR TO GEOID (PLUMBLINE) DEFLECTION OF THE VERTICAL DEFLEC99 TOPOGRAPHIC SURFACE h = Ellipsoidal Height N = Geoid Height

THE GEOID AND TWO ELLIPSOIDS NATIONAL OCEAN SERVICE GRS80-WGS84 CLARKE 1866 GEOID Earth Mass Center Approximately 236 meters

HORIZONTAL DATUMS BESSEL LOCAL ASTRO DATUMS ( ) NEW ENGLAND DATUM ( ) U.S. STANDARD DATUM ( ) NORTH AMERICAN DATUM ( ) NORTH AMERICAN DATUM OF 1927 OLD HAWAIIAN DATUM CLARKE 1866 PUERTO RICO DATUM ST. GEORGE ISLAND - ALASKA ST. LAWRENCE ISLAND - ALASKA ST. PAUL ISLAND - ALASKA AMERICAN SAMOA 1962 GUAM 1963 GRS NORTH AMERICAN DATUM OF 1983 (As of June 14, 1989) NATIONAL OCEAN SERVICE

NO SPCS EXISTING NAD 27 ENACTED NAD 83 SPC LEGISLATION LEGISLATION LEGISLATION (4) (3) (45) District of Columbia Alabama AlaskaMaryland (S) Oklahoma (S) Hawaii ArkansasArizona (I)Massachusetts (S) Oregon (I) Nebraska Illinois California (S)Michigan (I) Pennsylvania (S) Puerto Rico Colorado (S)Minnesota Rhode Island Connecticut (S)Mississippi (S) South Carolina (I) I = International Feet and Meters Delaware(S)Missouri South Dakota 1 m = feetFlorida (S) Montana Tennessee (S) S = U.S. Survey Feet and MetersGeorgia (S) Nevada Texas (S) 1 m = feet Idaho (S) New Hampshire Utah (I) Indiana (S) New Jersey Vermont Iowa New Mexico (S) Virginia (S) Kansas New York (S) Washington (S) Kentucky (S) North Carolina (S) West Virginia Louisiana North Dakota (I) Wisconsin (S) Maine Ohio Wyoming STATUS OF NAD 27 AND NAD 83 STATE PLANE COORDINATE LEGISLATION - AUGUST 1999

GROUND LEVEL COORDINATES “I WANT STATE PLANE COORDINATES RAISED TO GROUND LEVEL” GROUND LEVEL COORDINATES ARE NOT STATE PLANE COORDINATES!!!!! NATIONAL OCEAN SERVICE

IMPROVING POSITIONAL ACCURACY TIME NETWORK LOCAL NETWORK SPAN ACCURACY ACCURACY NAD Meters First-Order (1 part in 0.1 million) NAD Meter First-Order(1 part in 0.1 million) HARN Meter B-Order(1 part in 1 million) A-Order (1 part in 10 million) CORS Meter - Horizontal 0.04 Meter - Ellipsoid Height NATIONAL OCEAN SERVICE

WORLD GEODETIC SYSTEM 1984 DATUM = WGS 84(G730) 5 USAF GPS Tracking Stations 5 DMA Evaluation Stations Datum redefined with respect to the International Terrestrial Reference Frame of 1992 (ITRF92) +/- 20 cm in each component (Proceedings of the ION GPS-94 pgs ) DATUM = WGS 84(G873) 5 USAF GPS Tracking Stations 7 NIMA Evaluation Stations Datum redefined with respect to the International Terrestrial Reference Frame of 1994 (ITRF94) +/- 10 cm in each component (Proceedings of the ION GPS-97 pgs ) DoD World Geodetic System Its Definition and Relationships with Local Geodetic Systems (also: )

VERTICAL DATUMS MEAN SEA LEVEL DATUM OF 1929 NATIONAL GEODETIC VERTICAL DATUM OF 1929 ( As of July 2, 1973 ) NORTH AMERICAN VERTICAL DATUM OF 1988 ( As of June 24, 1993 ) NATIONAL OCEAN SERVICE

GEOID MODELS OSU 78 OSU 89B GEOID 90 GEOID 93 GEOID 96 GEOID 99 GEOID2000??? NATIONAL OCEAN SERVICE

GEODETIC CONTROL NETWORK OF MONUMENTED POINTS PRECISELY MEASURED IN ACCORDANCE WITH STANDARD PROCEDURES MEET ACCURACY SPECIFICATIONS ADJUSTED TO TIE TOGETHER DOCUMENTED FOR MULTIPLE USE NATIONAL OCEAN SERVICE

GEODETIC CONTROL DATA SHEET 1 National Geodetic Survey, Retrieval Date = DECEMBER 20, 1999 *********************************************************************** KZ2107 CBN - This is a Cooperative Base Network Control Station. KZ2107 DESIGNATION - BLACK KZ2107 PID - KZ2107 KZ2107 STATE/COUNTY- OH/HANCOCK KZ2107 USGS QUAD - RAWSON (1973) KZ2107 KZ2107 *CURRENT SURVEY CONTROL KZ2107 ___________________________________________________________________ KZ2107* NAD 83(1995) (N) (W) ADJUSTED KZ2107* NAVD (meters) (feet) ADJUSTED KZ2107 ___________________________________________________________________ KZ2107 X - 519, (meters) COMP KZ2107 Y - -4,800, (meters) COMP KZ2107 Z - 4,153, (meters) COMP KZ2107 LAPLACE CORR (seconds) DEFLEC99 KZ2107 ELLIP HEIGHT (meters) GPS OBS KZ2107 GEOID HEIGHT (meters) GEOID99 KZ2107 DYNAMIC HT (meters) (feet) COMP KZ2107 MODELED GRAV- 980,118.4 (mgal) NAVD 88 KZ2107 KZ2107 HORZ ORDER - B KZ2107 VERT ORDER - FIRST CLASS II KZ2107 ELLP ORDER - FOURTH CLASS II

GEODETIC CONTROL DATA SHEET KZ2107: Primary Azimuth Mark Grid Az KZ2107:SPC OH N - BLACK AZ MK KZ2107:UTM 17 - BLACK AZ MK KZ2107 KZ2107| | KZ2107| PID Reference Object Distance Geod. Az | KZ2107| dddmmss.s | KZ2107| KZ2433 BLACK RM METERS | KZ2107| KZ2434 BLACK RM METERS | KZ2107| KZ2420 BLACK AZ MK | KZ2107| | KZ2107 KZ2107 SUPERSEDED SURVEY CONTROL KZ2107 KZ2107 NAD 83(1986) (N) (W) AD( ) 1 KZ2107 NAD 83(1986) (N) (W) AD( ) 1 KZ2107 NAD (N) (W) AD( ) 1 KZ2107 NGVD (m) (f) LEVELING 3 KZ2107 KZ2107.Superseded values are not recommended for survey control. KZ2107.NGS no longer adjusts projects to the NAD 27 or NGVD 29 datums. KZ2107.See file dsdata.txt to determine how the superseded data were derived.

GEODETIC CONTROL DATA SHEET KZ2107_MARKER: DS = TRIANGULATION STATION DISK KZ2107_SETTING: 7 = SET IN TOP OF CONCRETE MONUMENT KZ2107_STAMPING: BLACK 1943 KZ2107_MAGNETIC: N = NO MAGNETIC MATERIAL KZ2107_STABILITY: C = MAY HOLD, BUT OF TYPE COMMONLY SUBJECT TO KZ2107+STABILITY: SURFACE MOTION KZ2107_SATELLITE: THE SITE LOCATION WAS REPORTED AS SUITABLE FOR KZ2107+SATELLITE: SATELLITE OBSERVATIONS - August 07, 1995 KZ2107 HISTORY - Date Condition Recov. By KZ2107 HISTORY MONUMENTED CGS KZ2107 HISTORY GOOD CGS KZ2107 HISTORY GOOD CGS KZ2107 HISTORY GOOD CGS KZ2107 HISTORY GOOD NGS KZ2107 HISTORY GOOD KZ2107 HISTORY GOOD OHDT KZ2107 HISTORY GOOD KZ2107 HISTORY GOOD NGS KZ2107 HISTORY GOOD OH-063 KZ2107 HISTORY GOOD NGS KZ2107 STATION DESCRIPTION KZ2107'DESCRIBED BY COAST AND GEODETIC SURVEY 1943 (APR) KZ2107'STATION IS LOCATED ABOUT 3.9 MILES E OF BLUFFTON IN THE NE ANGLE OF KZ2107'THE INTERSECTION OF STATE HIGHWAYS 103 AND 69. THE MARK IS SET IN THE NE

GEODETIC CONTROL DATA SHEET KZ2107.The horizontal coordinates were established by GPS observations KZ2107.and adjusted by the National Geodetic Survey in August KZ2107 KZ2107.The orthometric height was determined by differential leveling KZ2107.and adjusted by the National Geodetic Survey in January KZ2107 KZ2107.The X, Y, and Z were computed from the position and the ellipsoidal ht. KZ2107 KZ2107.The Laplace correction was computed from DEFLEC99 derived deflections. KZ2107 KZ2107.The ellipsoidal height was determined by GPS observations KZ2107.and is referenced to NAD 83. KZ2107 KZ2107.The geoid height was determined by GEOID99. KZ2107 KZ2107.The dynamic height is computed by dividing the NAVD 88 KZ2107.geopotential number by the normal gravity value computed on the KZ2107.Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45 KZ2107.degrees latitude (G = gals.). KZ2107 KZ2107.The modeled gravity was interpolated from observed gravity values. KZ2107 KZ2107; North East Units Scale Converg. KZ2107;SPC OH N - 137, , MT KZ2107;UTM ,530, , MT

Autonomous Positioning: Today C/A Code on L1 Selective Availability m HORIZONTAL = 100 meters VERTICAL = 156 meters 1996 Federal Radionavigation Plan Section A2-1, Part B

Standalone Positioning: By 2006 C/A Code on L1 No Selective Availability 6-11 m

GLOBAL POSITIONING SYSTEM GPS BLOCK IIF Potential Future Developments satellites Second and Third Civil Frequency ( MHZ & MHZ) More Robust Signal Transmissions Real-Time Unaugmented 1 Meter Accuracy Initial Launches ~ 2005 Complete Replacements ~ 2011 NATIONAL OCEAN SERVICE

GLOBAL NAVIGATION SATELLITE SYSTEMS (GNSS) POTENTIAL FUTURE DEVELOPMENTS ( ) US GPS MODERNIZATION - BLOCK IIF RUSSIAN GLONASS ENHANCEMENTS EUROPEAN UNION - GALILEO 60+ Satellites Second and Third Civil Frequency - GPS No Signal Encryption - GLONASS & GALILEO More Robust Signal Transmissions Real-Time Unaugmented 1 Meter (or better!) Accuracy NATIONAL OCEAN SERVICE

Standalone Positioning: By 2011 C/A Code on L1 C/A Code on L2 New Code on L5 1-3 m Better resistance to interference

INTERNATIONAL TERRESTRIAL REFERENCE FRAME NATIONAL OCEAN SERVICE DEVELOPED AND MAINTAINED BY THE INTERNATIONAL EARTH ROTATION SERVICE PARIS, FRANCE FROM: ( VERY LONG BASELINE INTERFEROMETRY - (VLBI) SATELLITE LASER RANGING - (SLR) GLOBAL POSITIONING SYSTEM - (GPS) DOPPLER ORBITOGRAPHY AND RADIO POSITIONING INTEGRATED BY SATELLITE - (DORIS)

INTERNATIONAL TERRESTRIAL REFERENCE FRAME GEOCENTRIC +/- 3 to 4 CM MODELS FOR PLATE TECTONICS STATION VELOCITIES POSITIONAL STANDARD ERRORS USUALLY BI-ANNUAL PUBLICATION NATIONAL OCEAN SERVICE

CONVENTIONAL TERRESTRIAL SYSTEM (CTS) Z CTS Y CTS X CTS X Y Z Greenwich Meridian Equator Earth Mass Center NATIONAL OCEAN SERVICE P X,Y,Z

NAD 83 and ITRF NATIONAL OCEAN SERVICE ITRF NAD 83 Earth Mass Center 2.2 m (3-D) dX,dY,dZ GEOID

ITRF96 (Epoch ) to NAD83 ftp://ftp.ngs.noaa.gov/pub/pcsoft/htdp/  X = meters  Y = meters  Z = meters rX = seconds rY = seconds rZ = seconds Scale = 0.0 ppm NATIONAL OCEAN SERVICE

ITRF94 (Epoch ) to NAD83 ftp://ftp.ngs.noaa.gov/pub/pcsoft/htdp/  X = meters  Y = meters  Z = meters rX = seconds rY = seconds rZ = seconds Scale = 0.0 ppm NATIONAL OCEAN SERVICE

NAD 83 NETWORK PROBLEMS NOT “GPSABLE” POOR STATION ACCESSIBILITY IRREGULARLY SPACED POSITIONAL ACCURACY NATIONAL OCEAN SERVICE

HIGH ACCURACY REFERENCE NETWORKS “GPSABLE” Clear Horizons for Satellite Signal Acquisition EASY ACCESSIBILITY Few Special Vehicle or Property Entrance Requirements REGULARLY SPACED Always within Km HIGH HORIZONTAL ACCURACY A-Order (5 mm + 1:10,000,000) B-Order (8mm + 1:1,000,000) NATIONAL OCEAN SERVICE

FEDERAL BASE NETWORK NGS FUNDED NGS MARK MAINTENANCE MAXIMUM 100 KM STATION SPACING A and B-ORDER HORIZONTAL ACCURACY FIRST-ORDER CLASS II ORTHOMETRIC HEIGHTS or SECOND-ORDER CLASS I ORTHOMETRIC HEIGHTS SECOND-ORDER CLASS I ELLIPSOIDAL HEIGHTS REVISIT EVERY 3 TO 5 YEARS NATIONAL OCEAN SERVICE

COOPERATIVE BASE NETWORK STATE/LOCAL FUNDED STATE/LOCAL MARK MAINTENANCE 25 TO 30 KM STATION SPACING B-ORDER HORIZONTAL ACCURACY THIRD-ORDER CLASS I ORTHOMETRIC HEIGHTS THIRD-ORDER CLASS I ELLIPSOIDAL HEIGHTS REVISIT AS NECESSARY NATIONAL OCEAN SERVICE

HIGH ACCURACY REFERENCE NETWORKS NATIONAL OCEAN SERVICE

USER DENSIFICATION NETWORK FEDERAL-STATE-LOCAL FUNDING STATION SPACING AS REQUIRED GPS OBSERVATIONS ONLY (HORIZONTAL) FIRST-ORDER HORIZONTAL ACCURACY REVISIT AS NEEDED NATIONAL OCEAN SERVICE

HARN ADJUSTMENT A-Order Adjusted to VLBI-Existing FBN-CORS B-Order Adjusted to A-Order Existing Horizontal (Conventional & GPS) Readjusted to A/B-Order New Adjustment Date Tag e.g. NAD 83(1995) [e.g. Michigan = NAD 83 (1994), Indiana = NAD 83 (1997)] NATIONAL OCEAN SERVICE

HARN ADJUSTMENT NAD 83 Data that is NOT Part of NSRS must be readjusted by contractor/user with original observations NATIONAL OCEAN SERVICE

NAD 83 READJUSTMENT HARN COMPLETION - SEPTEMBER 1997 (Indiana) GPS HEIGHT MODERNIZATION OBSERVATIONS ( ?) (Ohio not yet scheduled) ( COMPLETE GPS NAD 83 3-D ADJUSTMENT ( (2002?) REMOVAL OF SMALL REGIONAL DISTORTIONS (3 - 6 CM) UNIFORM COORDINATE TAG NAD 83 (NSRS02) NATIONAL OCEAN SERVICE

NAD 83 READJUSTMENT

ONLY GPS DATA CONTINUOUSLY OPERATING REFERENCE STATIONS FEDERAL BASE NETWORK COOPERATIVE BASE NETWORK AIRPORT SURVEYS USER DENSIFICATION NETWORK SPECIAL SURVEYS NATIONAL OCEAN SERVICE

NAD 83 READJUSTMENT WILL NOT INCLUDE OLD CONVENTIONAL OBSERVATIONS TRIANGULATION TRAVERSE TRILATERATION INERTIAL PHOTOGRAMMETRY NATIONAL OCEAN SERVICE

NEW STANDARDS FOR GEODETIC CONTROL Two accuracy standards ( local accuracy adjacent points network accuracy relative to CORS Numeric quantities, units in cm (or mm) Both are relative accuracy measures Do not use distance dependent expression Horizontal accuracies are radius of 2-D 95% error circle Ellipsoidal/Orthometric heights are 1-D (linear) 95% error NATIONAL OCEAN SERVICE

DATUM TRANSFORMATIONS 1. WHAT DATUM ARE THE EXISTING COORDINATES ON? 2. WHAT DATUM DO I WANT THE NEW COORDINATES ON? 3. HOW LARGE A GEOGRAPHICAL AREA DO I WANT TO CONVERT AT ONE TIME? 4. HOW MANY POINTS ARE COMMON TO BOTH DATUMS? 5. WHAT IS THE DISTRIBUTION OF THE COMMON POINTS? 6. HOW ACCURATE ARE THE EXISTING COORDINATES? 0.1 Foot 1.0 Foot 10. Feet 7. HOW ACCURATE DO I WANT THE NEW COORDINATES? NATIONAL OCEAN SERVICE

DATUM TRANSFORMATIONS MOLODENSKY Converts latitude, longitude and ellipsoidal height to X,Y,Z Earth-Centered Coordinates. Applies a 3-dimensional change in the origin (dX, dY,dZ) Applies a change in the size and shape of the reference ellipsoid Converts new X,Y,Z Earth-Centered Coordinates back to latitude, longitude and ellipsoidal height NATIONAL OCEAN SERVICE

DATUM TRANSFORMATIONS MOLODENSKY For continental regions accuracy can be +/- 8 to 10 meters Does not model network distortions very well. Assumes heights in both systems are ellipsoidal (NAD 27 did not have ellipsoidal heights). NATIONAL OCEAN SERVICE

DATUM TRANSFORMATION - IDEAL METHOD SATISFIES ALL USERS’ REQUIREMENTS CAPABLE OF TRANSFORMING LARGE HOLDINGS OF COORDINATE DATA NEAR-REAL TIME APPLICATIONS SIMPLE - METHOD SHOULD NOT REQUIRE AN EXPERT OR DECISIONS TO BE MADE ACCURATE NATIONAL OCEAN SERVICE

NADCON DESIGNED TO SATISFY THE MAJORITY OF THE “IDEAL METHOD” DESIGN AND HAS DEFINED AS THE NATIONAL STANDARD. DESIGN CRITERIA : Relies only on NGS archived data existing in both NAD 27 and NAD 83 Provides consistent results, both forward and inverse Fast Not tied to NGS Data Base Small - Fit on PC Accurate 15 cm (1 sigma) in Conterminous U. S. NAD 27 - NAD 83(1986) 5 cm (1 sigma) per State/Region NAD 83 (1986) - HARN NATIONAL OCEAN SERVICE

COORDINATE COMPARISON NAD 27 to NAD 83(1986) MOLODENSKY ( ADJUSTED vs. TRANSFORMED Station: BLACK LATITUDE LONGITUDE PUBLISHED MOLODENSKY.01255”.12887” m m THIS CORRESPONDS TO A POSITIONAL DIFFERENCE OF m (9.98 ft)

COORDINATE COMPARISON NAD 27 to NAD 83(1986) NADCON (ftp://ftp.ngs.noaa.gov/pub/pcsoft/nadcon/) ADJUSTED vs. TRANSFORMED Station: BLACK LATITUDE LONGITUDE PUBLISHED NADCON.00310”.00375”.096 m.130 m THIS CORRESPONDS TO A POSITIONAL DIFFERENCE OF m (0.53 ft)

COORDINATE COMPARISON NAD 83 (1986) to NAD 83(1995) NADCON ADJUSTED vs. TRANSFORMED Station: BLACK LATITUDE LONGITUDE PUBLISHED NADCON.00115”.00161”.036 m.038 m THIS CORRESPONDS TO A POSITIONAL DIFFERENCE OF m (0.17 ft)

CONTINUOUSLY OPERATING REFERENCE STATIONS (CORS) Installed and Operated by various Federal-State-local Agencies NOAA/National Geodetic Survey NOAA/OAR Forecast Systems Lab U.S. Coast Guard - DGPS/NDGPS Corps of Engineers - DGPS FAA - WAAS/LAAS (Future) State DOTs County and City Academia Private Companies NATIONAL OCEAN SERVICE CHL1 - CAPE HENLOPEN, DE

CONTINUOUSLY OPERATING REFERENCE STATIONS (CORS) Variety of “Geodetic Quality” Dual-Frequency Antennas and Receivers Allen-Osborne (SNR 8000 & SNR 12 ACT) Ashtech (Z XII3) Leica (SR9500 & CRS1000) Trimble (4000SSE & 4000SSI) NATIONAL OCEAN SERVICE CHL1 - CAPE HENLOPEN, DE

CONTINUOUSLY OPERATING REFERENCE STATIONS (CORS) Some stations provide real-time code phase observations ” post-process carrier phase observations Free access via Internet (RINEX-2 Format) More than 170 Station National Network NATIONAL OCEAN SERVICE

CONTINUOUSLY OPERATING REFERENCE STATIONS (CORS) NGS PROVIDES Reference Site Survey Monumentation Horizontal and Vertical NSRS Connections NAD 83, ITRF94, ITRF96, ITRF97 Coordinates Network Data Collection - Hourly & Daily Daily 3D Network Integrity Adjustment Public Data Distribution - Internet ( 2 Years On-Line Data Holding NATIONAL OCEAN SERVICE

CORS DATA SHEET ***ITRF 96*** DETROIT 1 (DET1), MICHIGAN Retrieved from NGS DataBase on 09/28/98 at 08:38:44. ____________________________________________________________________________ | | | Antenna Reference Point(ARP): DETROIT 1 CORS ARP | | | | PID = AF9501 | | | | ITRF96 POSITION (EPOCH ) | | Computed in Mar., 1998 using 47 days of data. | | X = m latitude = N | | Y = m longitude = W | | Z = m ellipsoid height = m | | | | ITRF96 VELOCITY | | Computed in Mar., 1998 using 47 days of data. | | VX = m/yr northward = m/yr | | VY = m/yr eastward = m/yr | | VZ = m/yr upward = m/yr | | |

CORS DATA SHEET DETROIT 1 (DET1), MICHIGAN Retrieved from NGS DataBase on 09/28/98 at 08:38:44. ____________________________________________________________________________ | | | Antenna Reference Point(ARP): DETROIT 1 CORS ARP | | | | PID = AF9501 | | | | NAD_83 POSITION (EPOCH ) | | Transformed from ITRF94 (epoch ) position. | | X = m latitude = N | | Y = m longitude = W | | Z = m ellipsoid height = m | | | | NAD_83 VELOCITY | | Predicted with HTDP_2.0 in Apr., | | VX = m/yr northward = m/yr | | VY = m/yr eastward = m/yr | | VZ = m/yr upward = m/yr | |____________________________________________________________________________|

CONTINUOUSLY OPERATING REFERENCE STATIONS (CORS)

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