Transcript NATIONAL SPATIAL REFERENCE SYSTEM
DEVELOPMENT, IMPLEMENTATION AND FUTURE OF THE NATIONAL SPATIAL REFERENCE SYSTEM
HOUSTON DECEMBER 13, 2003
David Doyle Chief Geodetic Surveyor National Geodetic Survey [email protected], (301) 713-3178
ACRONYMS US
NATIONAL GEODETIC SURVEY INFORMATION CENTER (301) 713-3242 [email protected]
WEB SITE http://www.ngs.noaa.gov
GEODETIC CONTROL
NETWORK OF MONUMENTED POINTS PRECISELY MEASURED IN ACCORDANCE WITH STANDARD PROCEDURES MEET ACCURACY SPECIFICATIONS ADJUSTED TO TIE TOGETHER DOCUMENTED FOR MULTIPLE USE
Poured in place concrete post Stainless steel rod driven to refusal
CORS SITES
NATIONAL SPATIAL REFERENCE SYSTEM (http://www.ngs.noaa.gov)
The National Spatial Reference System (NSRS) is that component of the National Spatial Data Infrastructure (NSDI) [http://www.fgdc.gov/nsdi/nsdi.html] 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), and the National Shoreline as observed by NGS as well as data submitted by other Federal, State, and local agencies, Academic Institutions and the private sector
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 GPS Service etc.)
METADATA
METADATA IS DATA ABOUT DATA
DATUMS
NAD 27, NAD 83(1986), NAD83 (199X), NGVD29, NAVD88
UNITS
Meters, U.S. Survey Feet, International Feet, Vara, Toise, Chains, Rods, Poles, Links, Perchs, Smoots
ACCURACY
A, B, 1st, 2nd, 3rd, 3cm, Scaled
METADATA??
Horizontal Datum??
Plane Coordinate Zone ??
Units of Measure ??
How Accurate ??
METADATA??
Horizontal and Vertical Datums ??
How Accurate B-Order, 1 st -Order, 2cm, 0.01 ft??
THE ELLIPSOID MATHEMATICAL MODEL OF THE EARTH N b a S a = Semi major axis b = Semi minor axis f = a-b = Flattening a
ELLIPSOID - GEOID RELATIONSHIP
H = Orthometric Height (NAVD 88) h = Ellipsoidal Height (NAD 83) N = Geoid Height (GEOID 99) H = h N
TOPOGRAPHIC SURFACE
H h N
GEOID99 Geoid Ellipsoid GRS80
UNITED STATES ELLIPSOID DEFINITIONS
BESSEL 1841 a = 6,377,397.155 m 1/f = 299.1528128
CLARKE 1866 a = 6,378,206.4 m 1/f = 294.97869821
GEODETIC REFERENCE SYSTEM 1980 - (GRS 80) a = 6,378,137 m 1/f = 298.257222101
WORLD GEODETIC SYSTEM 1984 - (WGS 84) a = 6,378,137 m 1/f = 298.257223563
HORIZONTAL DATUMS
BESSEL 1841
--------------
CLARKE 1866 GRS80 -----------
LOCAL ASTRO DATUMS (1816-1879) NEW ENGLAND DATUM (1879-1901) U.S. STANDARD DATUM (1901-1913) NORTH AMERICAN DATUM (1913-1927) NORTH AMERICAN DATUM OF 1927 OLD HAWAIIAN DATUM PUERTO RICO DATUM ST. GEORGE ISLAND - ALASKA ST. LAWRENCE ISLAND - ALASKA ST. PAUL ISLAND - ALASKA AMERICAN SAMOA 1962 GUAM 1963 NORTH AMERICAN DATUM OF 1983 (As of June 14, 1989)
COMPARISON OF DATUM ELEMENTS
NAD 27 NAD 83 ELLIPSOID CLARKE 1866 GRS80 a = 6,378,206.4 m a = 6,378,137. M 1/f = 294.9786982 1/f = 298.257222101
DATUM POINT Triangulation Station NONE MEADES RANCH, KANSAS EARTH MASS CENTER ADJUSTMENT 25k STATIONS 250k STATIONS Several Hundred Base Lines Appox. 30k EDMI Base Lines Several Hundred Astro Azimuths 5k Astro Azimuths Doppler Point Positions VLBI Vectors BEST FITTING North America World-Wide
NAD 27 and NAD 83
NAD 83 NETWORK PROBLEMS
NOT “GPSABLE” POOR STATION ACCESSIBILITY IRREGULARLY SPACED POSITIONAL ACCURACY
HIGH ACCURACY REFERENCE NETWORKS
“GPSABLE” Clear Horizons for Satellite Signal Acquisition EASY ACCESSIBILITY Few Special Vehicle or Property Entrance Requirements REGULARLY SPACED Always within 20-100 Km HIGH HORIZONTAL ACCURACY A-Order (5 mm + 1:10,000,000) B-Order (8mm + 1:1,000,000)
IMPROVING POSITIONAL ACCURACY
TIME NETWORK LOCAL NETWORK SPAN ACCURACY ACCURACY NAD 27 1927-1986 10 Meters First-Order (1 part in 0.1 million) NAD 83 1986-1990 1 Meter First-Order(1 part in 0.1 million) HPGN/HARN 1987-1997 0.1 Meter B-Order(1 part in 1 million) A-Order (1 part in 10 million) CORS 1994 0.02 Meter - Horizontal 0.04 Meter - Ellipsoid Height
HIGH ACCURACY REFERENCE NETWORK
HIGH ACCURACY REFERENCE NETWORKS
TEXAS HARN
INTERNATIONAL TERRESTRIAL REFERENCE SYSTEM
DEVELOPED AND MAINTAINED BY THE INTERNATIONAL EARTH ROTATION AND REFERENCE SYSTEM SERVICE PARIS, FRANCE (http:// http://www.iers.org/) 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 SYSTEM
GEOCENTRIC +/- 3 to 4 CM MODELS FOR PLATE TECTONICS STATION VELOCITIES POSITIONAL STANDARD ERRORS REALIZED AS THE INTERNATIONAL TERRESTERIAL REFERENCE FRAME (ITRF)
WORLD GEODETIC SYSTEM 1984
TR8350.2 World Geodetic System 1984 It’s Definition and Relationships with Local Geodetic Systems
(http://www.nima.mil/GandG/pubs.html) DATUM = WGS 84(G730)
HOW MANY WGS 84s HAVE THERE BEEN????
(Proceedings of the ION GPS-97 pgs 841-850)
MY SOFTWARE SAYS I’M WORKING IN WGS-84
Unless you doing autonomous positioning (point positioning +/- 6-10 meters) you’re probably NOT in WGS-84 Project tied to WGS-84 control point obtained from the Defense Department -- Good Luck! - You’re really working in the same reference frame as your control points -- NAD 83?
TRANSFORM BETWEEN WGS 84 & NAD 83 dX = 0.9956 m dY = -1.9013 m dZ = -0.5215 m
THE GEOID AND TWO ELLIPSOIDS CLARKE 1866 GRS80-WGS84
Earth Mass Center Approximately 236 meters
GEOID
TECTONIC MOTIONS
HORIZONTAL TECTONIC MOTIONS
VERTICAL TECTONIC MOTIONS
NAD 83 and ITRF / WGS 84
NAD 83 ITRF / WGS 84
Earth Mass Center 2.2 m (3-D) dX,dY,dZ
GEOID
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 )
COMPARISON OF VERTICAL DATUM ELEMENTS
NGVD 29 NAVD 88 DATUM DEFINITION 26 TIDE GAUGES FATHER’S POINT/RIMOUSKI IN THE U.S. & CANADA QUEBEC, CANADA BENCH MARKS 100,000 450,000 LEVELING (Km) 102,724 1,001,500 GEOID FITTING Distorted to Fit MSL Gauges Best Continental Model
NGVD 29 and NAVD 88
MHHW
Datum’s Boundary Applications
NOS BENCHMARK LEVELING
Distances vary but usually several hundred meters.
GEOID MODELS
U.S. NATIONAL MODEL -- GEOID99
(http://www.ngs.noaa.gov/cgi bin/GEOID_STUFF/geoid99_prompt1.prl)
CANADIAN NATIONAL MODEL -- GSD95
http://www.geod.nrcan.gc.ca/products/html public/GSDinfo/English/factsheets/gpsht_fact.html
GLOBAL MODEL -- EGM 96
(http://www.nima.mil/GandG/wgs-84/egm96.html)
NEW U.S. GEOID MODEL
Release by January 2004
USGG2003 and GEOID03
USGG = U.S. Gravimetric Geoid GEOID03 = U.S. Hybrid Geoid
In excess of 11,000 GPS on BMs
(A, B, and 1 st - Order GPS on 1 st , 2 nd and 3 rd – Order NAVD 88 BMs)
Possibly overall misfit will be about 2.9 cm.
Standalone Positioning: Since May 1, 2000
6-11 m
C/A Code on L1 No Selective Availability
Standalone Positioning: By 2011
Better resistance to interference 1-3 m
C/A Code on L1 C/A Code on L2 New Code on L5
GLOBAL POSITIONING SYSTEM
GPS BLOCK III
Potential Future Developments 30 - 32 satellites Second and Third Civil Frequency (1227.60 MHZ & 1176.45 MHZ) More Robust Signal Transmissions Real-Time Unaugmented 1 Meter Accuracy Initial Launches ~ 2005 Complete Replacements ~ 2015??
GLOBAL NAVIGATION SATELLITE SYSTEMS (GNSS)
POTENTIAL FUTURE DEVELOPMENTS (2005 – 2015??) GPS MODERNIZATION - BLOCK III GLONASS ENHANCEMENTS EUROPEAN UNION - GALILEO 70- 90 Satellites Second and Third Civil Frequency - GPS No Signal Encryption - GLONASS & GALILEO More Robust Signal Transmissions Real-Time Unaugmented 1 Meter (or better!) Accuracy
GEODETIC DATA SHEET
Geodetic Data Sheets
GEODETIC DATA SHEET
GEODETIC DATA SHEET
National Geodetic Survey, Retrieval Date = NOVEMBER 15, 2003 BN0540 *********************************************************************** BN0540 FBN This is a Federal Base Network Control Station.
BN0540 DESIGNATION CHERRY BN0540 PID BN0540 H = h - N BN0540 STATE/COUNTY BN0540 USGS QUAD BN0540 BN0540* NAD 83(1993) TX/GILLESPIE CHERRY SPRING (1967) 542.73 = 520.52 - (- 22.17) 542.73 BN0540 *CURRENT SURVEY CONTROL
542.69
BN0540 ___________________________________________________________________ 30 29 48.47740(N) 099 00 39.29203(W) ADJUSTED BN0540* NAVD 88 BN0540 ___________________________________________________________________ BN0540 X 542.733 (meters) 1780.62 (feet) ADJUSTED -861,575.021 (meters) COMP BN0540 Y BN0540 Z BN0540 LAPLACE CORR BN0540 ELLIP HEIGHT BN0540 GEOID HEIGHT BN0540 DYNAMIC HT BN0540 MODELED GRAV BN0540 BN0540 HORZ ORDER BN0540 VERT ORDER BN0540 ELLP ORDER -5,433,071.971 (meters) COMP 3,218,212.963 (meters) COMP -2.38 (seconds) DEFLEC99 520.52 (meters) (05/01/00) GPS OBS 541.984 (meters) 1778.16 (feet) COMP 979,243.1 (mgal) NAVD 88 B FIRST CLASS II THIRD CLASS I
GEODETIC DATA SHEET
BN0540.The horizontal coordinates were established by GPS observations BN0540.and adjusted by the National Geodetic Survey in May 1994.
BN0540 BN0540.The orthometric height was determined by differential leveling BN0540.and adjusted by the National Geodetic Survey in June 1991.
BN0540 BN0540.The X, Y, and Z were computed from the position and the ellipsoidal ht.
BN0540 BN0540.The Laplace correction was computed from DEFLEC99 derived deflections.
BN0540 BN0540.The ellipsoidal height was determined by GPS observations BN0540.and is referenced to NAD 83.
BN0540 BN0540.The geoid height was determined by GEOID99.
BN0540 BN0540.The dynamic height is computed by dividing the NAVD 88 BN0540.geopotential number by the normal gravity value computed on the BN0540.Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45 BN0540.degrees latitude (g = 980.6199 gals.).
BN0540 BN0540.The modeled gravity was interpolated from observed gravity values.
BN0540 BN0540; North East Units Scale Converg.
BN0540;SPC TX C - 3,092,779.590 826,941.837 MT 0.99992026 +0 40 52.0
BN0540;UTM 14 - 3,373,836.874 498,952.609 MT 0.99960001 -0 00 19.9
BN0540
GEODETIC DATA SHEET
BN0540: Primary Azimuth Mark Grid Az BN0540:SPC TX C CHERRY AZ MK 183 41 09.7
BN0540:UTM 14 CHERRY AZ MK 184 22 21.6
BN0540 BN0540|---------------------------------------------------------------------| BN0540| PID Reference Object Distance Geod. Az | BN0540| dddmmss.s | BN0540| BN0541 CHERRY RM 2 7.440 METERS 00148 | BN0540| CV4542 CHERRY RM 1 7.675 METERS 17732 | BN0540| BN0539 CHERRY RM 3 7.710 METERS 17741 | BN0540| BN0538 CHERRY AZ MK 1842201.7 | BN0540| BN0722 LOYAL MTN MICROWE RADIO MAST APPROX. 9.3 KM 3531351.6 | BN0540|---------------------------------------------------------------------| BN0540 BN0540 SUPERSEDED SURVEY CONTROL BN0540 BN0540 ELLIP H (05/09/94) 520.61 (m) GP( ) 4 2 BN0540 NAD 83(1986) 30 29 48.49063(N) 099 00 39.27999(W) AD( ) 3 BN0540 NAD 27 BN0540 30 29 47.81630(N) 099 00 38.10070(W) AD( ) 3 BN0540 NAVD 88 (05/09/94) 542.73 (m) 1780.6 (f) LEVELING 3 BN0540 NGVD 29 (10/23/89) 542.68 (m) 1780.4 (f) LEVELING 3 BN0540.Superseded values are not recommended for survey control.
BN0540.NGS no longer adjusts projects to the NAD 27 or NGVD 29 datums.
BN0540.See file dsdata.txt to determine how the superseded data were derived.
GEODETIC DATA SHEET
BN0540_U.S. NATIONAL GRID SPATIAL ADDRESS: 14RMU9895373837(NAD 83) BN0540_MARKER: DS = TRIANGULATION STATION DISK BN0540_SETTING: 7 = SET IN TOP OF CONCRETE MONUMENT BN0540_STAMPING: CHERRY 1956 BN0540_MARK LOGO: CGS BN0540_PROJECTION: PROJECTING 12 CENTIMETERS BN0540_MAGNETIC: O = OTHER; SEE DESCRIPTION BN0540_STABILITY: C = MAY HOLD, BUT OF TYPE COMMONLY SUBJECT TO BN0540+STABILITY: SURFACE MOTION BN0540_SATELLITE: THE SITE LOCATION WAS REPORTED AS SUITABLE FOR BN0540+SATELLITE: SATELLITE OBSERVATIONS - September 05, 2001 BN0540 BN0540 HISTORY - Date Condition Report By BN0540 HISTORY - 1956 MONUMENTED CGS BN0540 HISTORY - 1969 GOOD CGS BN0540 HISTORY - 1982 GOOD NGS BN0540 HISTORY - 19890106 GOOD NGS BN0540 HISTORY - 19930306 GOOD NGS BN0540 HISTORY - 19960309 GOOD USPSQD BN0540 HISTORY - 19980307 GOOD NGS BN0540 HISTORY - 20010905 GOOD INDIV BN0540 BN0540 STATION DESCRIPTION BN0540 BN0540'DESCRIBED BY COAST AND GEODETIC SURVEY 1956 (WFD) BN0540'THE STATION IS 0.65 MILE NORTH OF CHERRY SPRINGS, 0.1 MILE BN0540'SOUTH OF THE GILLESPIE-MASON COUNTY LINE AND ON THE RIGHT-OF-WAY
GEODETIC CONTROL DATA SHEET
National Geodetic Survey, Retrieval Date = SEPTEMBER 11, 2003 TA0047 *********************************************************************** TA0047 DESIGNATION G 216 TA0047 PID TA0047 Up dated position by hand held GPS TA0047 STATE/COUNTY MN/COOK TA0047 USGS QUAD LONG ISLAND LAKE (1986) TA0047 TA0047 *CURRENT SURVEY CONTROL TA0047 ___________________________________________________________________ TA0047* NAD 83(1986) 48 04 54.20 (N) 090 45 48.42 (W) HD_HELD1 TA0047* NAVD 88 TA0047 ___________________________________________________________________ TA0047 GEOID HEIGHT 512.698 (meters) 1682.08 (feet) ADJUSTED -30.65 (meters) GEOID99 TA0047 DYNAMIC HT 512.802 (meters) 1682.42 (feet) COMP TA0047 MODELED GRAV TA0047 TA0047 VERT ORDER 980,798.7 (mgal) NAVD 88 SECOND CLASS 0 TA0047 TA0047.The horizontal coordinates were established by differentially corrected TA0047.hand held GPS obs and have an estimated accuracy of +/- 3 meters.
TA0047 TA0047.The orthometric height was determined by differential leveling TA0047.and adjusted by the National Geodetic Survey in June 1991.
TA0047 TA0047.Photographs are available for this station.
TA0047 TA0047; North East Units Estimated Accuracy TA0047;SPC MN N 278,477.4 974,048.5 MT (+/- 3 meters HH1 GPS) TA0047
ONLY GPS DATA CONTINUOUSLY OPERATING REFERENCE STATIONS FEDERAL BASE NETWORK COOPERATIVE BASE NETWORK USER DENSIFICATION NETWORK LAYERED ADJUSTMENT OF 3,000 INDIVIDUAL PROJECTS INLCUDING MORE THAN 59,000 STATIONS BOTH NAD 83(NSRS) AND ITRF COORDINATES WILL BE PUBLISHED
NETWORK READJUSTMENTS NAD 83 data that is
NOT
part of NSRS must be readjusted by contractor/user with original observations
NEW STANDARDS FOR GEODETIC CONTROL Two accuracy standards
( http://fgdc.er.usgs.gov/standards/status/swgstat.html
) 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
CONTINUOUSLY OPERATING REFERENCE STATIONS (CORS)
Installed and Operated by various Federal-State-local Agencies
CHL1 - CAPE HENLOPEN, DE
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
CONTINUOUSLY OPERATING REFERENCE STATIONS (CORS)
Variety of “Geodetic Quality” Dual-Frequency
CHL1 - CAPE HENLOPEN, DE
Antennas and Receivers
Allen-Osborne Ashtech/Thales Leica Trimble
CONTINUOUSLY OPERATING REFERENCE STATIONS (CORS)
Some stations provide real-time code phase observations 1-5 - 15 30” post-process carrier phase observations Free access via Internet (RINEX-2 Format) More than 425 Station National Network
CONTINUOUSLY OPERATING REFERENCE STATIONS (CORS)
NGS PROVIDES
Reference Site Survey Monumentation Horizontal and Vertical NSRS Connections NAD 83, ITRF94, ITRF96, ITRF97, ITRF00 Coordinates Network Data Collection - Hourly & Daily Daily 3D Network Integrity Adjustment Public Data Distribution - Internet ( http://www.ngs.noaa.gov/CORS/cors-data.html
) 9 Year On-Line Data Holding
***ITRF 00*** HOUSTON RRP2 (TXHU), TEXAS Retrieved from NGS DataBase on 11/15/03 at 14:14:49.
____________________________________________________________________________ | | | Antenna Reference Point(ARP): HOUSTON RRP2 CORS ARP | | -------------------------------------------------- | | PID = DF4379 | | | | | | ITRF00 POSITION (EPOCH 1997.0) | | Computed in Mar., 2003 using 13 days of data. | | X = -524578.515 m latitude = 29 46 45.91022 N | | Y = -5515562.145 m longitude = 095 25 58.76631 W | | Z = 3149180.614 m ellipsoid height = 12.001 m | | | | ITRF00 VELOCITY | | Set equal to vel of hous Mar., 2003. | | VX = -0.0145 m/yr northward = -0.0045 m/yr | | VY = 0.0096 m/yr eastward = -0.0153 m/yr | | VZ = -0.0099 m/yr upward = -0.0120 m/yr | | | | | | NAD_83 POSITION (EPOCH 2002.0) | | Transformed from ITRF00 (epoch 1997.0) position in Mar., 2003. | | X = -524577.977 m latitude = 29 46 45.89147 N | | Y = -5515563.571 m longitude = 095 25 58.74137 W | | Z = 3149180.732 m ellipsoid height = 13.247 m | | | | NAD_83 VELOCITY | | Transformed from ITRF00 velocity in Mar., 2003. | | VX = -0.0008 m/yr northward = -0.0002 m/yr | | VY = 0.0108 m/yr eastward = -0.0018 m/yr | | VZ = -0.0063 m/yr upward = -0.0124 m/yr | |____________________________________________________________________________|
CORS DATA QUALITY
IGS Tracking Network
http://igscb.jpl.nasa.gov/
OPUS – WHAT IS IT?
• O
n-line
P
ositioning
U
ser
S
ervice •Provide GPS users faster & easier access to the National Spatial Reference System (NSRS)
OPUS – HOW DOES IT WORK?
•Submit RINEX file through NGS web page •Processed automatically with NGS computers & software •With respect to 3 suitable or user-selected National CORS •Solution via email in minutes
OPUS – HOW DO I USE IT?
•Go to OPUS web page •Enter your email address www.ngs.noaa.gov/OPUS •Use browse feature to select RINEX file on your computer •Select antenna type from menu •Enter antenna height in meters •Option to select State Plane Zone •Click UPLOAD •Check your email in a few minutes
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?
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
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).
Earth-Centered Earth-Fixed (ECEF) Coordinate System
Z
A
(X,Y,Z,) Latitude Longitude Ellipsoid Height X
- Y Earth Mass Center Y A Equator - Z Z A X A - X
Y
Earth-Centered Earth-Fixed (ECEF) Coordinate System
X Z
A Z A Y A X A
Y X Z
A Z B Y B X B
Y
X
3 Parameter Molodensky Transformation “In The Real World”
Z
A Z B
Z
A Z A dX
X
dY Y B dZ X B
Y
Y A X A
Y
I NEED TO TRANSFORM BETWEEN NAD 27 AND WGS 84
I NEED TO TRANSFORM BETWEEN NAD 27 AND WGS 84
MOLODENSKY TRANSFORMATION
COMPUTED vs. MODELED Station: CHERRY NAD 27 X = -861,565.807 m NAD 83(1992) dX, dY,dZ X = - 861,575.021 m - 9.214 m Y = - 5,433,217.188 m Y = - 5,433,071.971 m + 145.217 m Z = +3,218,031.876 m Z = + 3,218,212.963 m + 181.087 m COMPUTED NIMA EAST dX = - 9 m dX = -9 (0 m) dY = + 145 dY = + 161 (16 m) dZ = + 181 dZ = + 179 (2 m) NIMA CONUS dX = -8 (1m) dY = + 160 (15 m) dZ = + 176 (5 m)
DATUM TRANSFORMATION IDEAL METHOD
SATISFIES ALL USERS’ REQUIREMENTS CAPABLE OF TRANSFORMING LARGE HOLDINGS OF COORDINATE DATA NEAR-REAL TIME APPLICATIONS SIMPLE METHOD SHOULD DECISIONS TO BE MADE NOT REQUIRE AN EXPERT OR ACCURATE
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
N
= +0.12344
8
= -1.87842
N
= +0.12438
8
= -1.86547
NADCON
N
= +0.12354
8
= -1.8594
N
= +0.12431
8
= -1.86291
N
= +0.12449
8
= -1.88905
N
= +0.12423
8
= -1.81246
N
= +0.12441
8
= -1.83879
N
= +0.12249
8
= -1.88963
N
= +0.12568
8
= -1.83364
N
= +0.12640
8
= -1.85407
N
= +0.12499
8
= -1.86543
COORDINATE TRANSFORMATION COMPARISON NAD 27 to NAD 83(1992)
MOLODENSKY ADJUSTED vs. TRANSFORMED Station: CHERRY MOLODENSKY LATITUDE LONGITUDE 30-29- 48.47740 099-00-39.29203 - PUBLISHED 30-29-48.67650
099-00-39.37955 .19910” .08752” 6.131 m 2.334 m THIS CORRESPONDS TO A POSITIONAL DIFFERENCE OF 6.560 m (21.52 ft)
COORDINATE TRANSFORMATION COMPARISON NAD 27 to NAD 83(1992)
NADCON (ftp://ftp.ngs.noaa.gov/pub/pcsoft/nadcon/) ADJUSTED vs. TRANSFORMED Station: CHERRY LATITUDE LONGITUDE 30-29-48.47740 099-00-39.29203 - PUBLISHED 30-29-48.48670
099-00-39.28787 - NADCON .00930” .00416” 0.286 m 0.111 m THIS CORRESPONDS TO A POSITIONAL DIFFERENCE OF 0.307 m (1.01 ft)
GPS NETWORKS TO SUPPORT GIS
“CLASSICAL” Lots of control points spaced at regular intervals (1-3 miles) “CONTEMPORARY” CORS and Monumentation as needed
GPS NETWORKS TO SUPPORT GIS OBSERVE TO NATIONAL STANDARDS TIES TO CORS, HARN and LOCAL BMs QUALITY MONUMENTATION
GPS NETWORKS TO SUPPORT GIS CLASSICAL
GPS NETWORKS TO SUPPORT GIS
CONTEMPORARY
CLASSICAL GPS NETWORKS PROS
Monumentation usually established in only 1 or 2 GPS survey campaigns Complete coverage No time lag for users access to control
CONS
Large initial cost Continual network maintenance Monumentation destroyed or disturbed before they’re used
CONTEMPORARY GPS NETWORKS
PROS
Minimal “permanent” monumentation Project control established when and where needed Costs spread over time
CONS
Qualified staff to coordinate user requirements Time lag to establish project control
GPS NETWORKS TO SUPPORT GIS GPS SURVEY DATA
“BLUE - BOOK” SUBMISSION OF DATA FOR INCLUSION IN NSRS OR DATA MAINTAINED AT THE LOCAL LEVEL
GPS NETWORKS TO SUPPORT GIS “BLUE-BOOK”
PROS
DATA MAINTAINED IN NSRS IN PERPETUTITY PROVIDES IMPROVED DATA FOR FUTURE NATIONAL GEOID MODELS UNIVERSAL DATA ACCESS VIA NGS WEB SITE “GOOD HOUSEKEEPING SEAL OF APPROVAL”
CONS
INCREASED INITIAL COST (15 - 20%) SLIGHT INCREASE IN INITIAL DATA PROCESSING TIME
GPS NETWORKS TO SUPPORT GIS LOCAL MAINTENANCE
PROS
DECREASED INITIAL SURVEY COSTS LOCAL CONTROL OF ALL DATA
CONS
READJUSTMENTS TO FUTURE REFERENCE FRAME CHANGES MUST BE DONE AT THE LOCAL LEVEL DATA MAY BE DIFFICULT TO LOCATE FOR “NON-LOCALS” DATA DOES NOT CONTRIBUTE TO FUTURE NATIONAL GEOID MODELS
GOOD COORDINATION BEGINS WITH GOOD COORDINATES
GEOGRAPHY WITHOUT GEODESY IS A FELONY