Post on 12-Mar-2018
PROFESSIONAL LAND SURVEYORS OF OREGON SALEM
JANUARY 23, 2014
Dave Doyle Base 9 Geodetic Consulting Services National Geodetic Survey (Retired)
base9geodesy@gmail.com
GPS-DERIVED HEIGHTS
ELLIPSOID - GEOID RELATIONSHIP
H = Orthometric Height (NAVD 88)
H = h – N
h = Ellipsoid Height (NAD 83 (2011))
N = Geoid Height (GEOID12A)
H h
Ellipsoid GRS80
N
Geoid “Mean Sea Level”
Geoid Model
MONUMENTS IN THE GROUND
ANTENNAS IN THE AIR
LEVELING (mm accuracy)
(very expensive, time consuming, highly trained personnel)
And/Or
GNSS
(several cm accuracy) (cheaper, quicker, fewer trained personnel)
HOW ARE ACCURATE HEIGHTS MEASURED?
GEODETIC DATUMS HORIZONTAL
2 D (Latitude and Longitude) (e.g. U.S. Standard Datum, NAD 27, NAD 83 (1986)) Fixed and Stable - Coordinates seldom change
GEOMETRIC 3-D (Latitude, Longitude and Ellipsoid Height)
Fixed and Stable - Coordinates seldom change (e.g. NAD 83 (“HARN”), NAD 83 (CORS96), NAD 83 (2007), NAD 83 (2011))
4-D (Latitude, Longitude, Ellipsoid Height, Velocities) Coordinates change with time (e.g. ITRF00, IGS08)
VERTICAL
1 D (Orthometric Height) (Leveling constrained to 1 or more long-term tide stations) (e.g. NGVD 29, NAVD 88, PRVD 02, VIVD 09 etc.)
GEOPOTENTIAL 1 D (Orthometric Height) (Realized by GNSS + High Accuracy Gravimetric Geoid Model)
(e.g. GRAV-D)
NATIONAL SPATIAL REFERENCE SYSTEM(NSRS)
Consistent National Coordinate System
• Latitude • Longitude
• Height • Scale
• Gravity • Orientation
and how these values change with time
• National Shoreline - Consistent, accurate, and up-to-date
• National and Cooperative CORS - A network of GPS Continuously Operating Reference Stations
• Networks of geodetic control points - Permanently marked passive survey monuments
• Tools -Models of geophysical effects on spatial measurements -e.g., NADCON, INVERSE, SPCS83, UTMS, FORWARD
NSRS COMPONENTS
• Tools -Models of geophysical effects on spatial measurements -e.g., NADCON, INVERSE, SPCS83, UTMS, FORWARD
SUBSIDENCE: 10 MM/YEAR TO OVER 27 MM/YR
WHEN WAS THE PASSIVE MARK ACCESSED?
METADATA DATA ABOUT DATA
DATUMS
NAD 27, NAD 83(1986), NAD83 (1992), NAD 83 (2007), NAD 83 (2011), NGVD29, NAVD88
UNITS
Meters, U.S. Survey Feet, International Feet
ACCURACY A-Order, B-Order, 1st, 2nd, 3rd, 3cm, .02 ft, Scaled
ON JUNE 20, THE M/V ZHEN HUA 13 DELIVERED NEW CRANES FROM CHINA TO THE PORT OF BALTIMORE BY NAVIGATING THE WATERS OF CHESAPEAKE BAY
Metadata Needed: - Local tidal datum
reference - Tide info. - Channel bathymetry - Bridge dimensions - Bridge elevation- datum
& accuracy - Ship squat - Crane height from keel - Water currents/ wave
chop
GEOSPATIAL DATA REQUIRES METADATA!
N E H PT 1,323922.832,2211566.199,398.638,HOLE 2,323910.487,2211572.158,398.101,MHSS 3,323993.852,2211224.037,428.904,MHSS 4,324077.107,2211089.654,444.897,MHSS 5,324077.559,2211098.749,444.796,PKNL 6,327586.448,2208838.501,383.945,DOT 7,327585.974,2208850.829,384.221,PIPE 8,327539.388,2209077.976,394.788,MONU 9,327530.076,2209127.079,396.808,MONU 10,327530.078,2209127.080,396.787,MONU DATUM INFO Leica Smart Net North America Pennsylvania State Plane (South Zone) Horizontal-NAD 83 (2011) Vertical- NAVD 88 Observation Date-1/20/2014
TYPES OF HEIGHTS
ORTHOMETRIC The distance between the geoid and a point on the Earths surface measured along
the plumb line. (From Leveling 0.1 – 2 cm / .003 – 0.06 ft)
GEOID
The distance along a perpendicular from the ellipsoid of reference to the geoid (From Model 1-5 cm / .03 – .16 ft)
ELLIPSOID
The distance along a perpendicular from the ellipsoid to a point on the Earth’s surface.
(From GNSS Observations 1-5 cm / .03 – .16 ft)
VERTICAL DATUMS
A set of fundamental elevations to which other elevations are referred.
Datum Types
Tidal – Defined by observation of tidal variations over some period of time (MSL, MLLW, MLW, MHW, MHHW etc.)
Geodetic – Either directly or loosely based on Mean Sea Level at one or more points at some epoch
(NGVD 29, NAVD 88, IGLD85 etc.)
AL, AK, CA, CT, FL, GA, LA, MD, MS, NJ, NY, NC, OR, RI, SC, WA
Privately Owned Uplands
State Owned Tidelands
Territorial Seas
State Submerged Lands
Contiguous Zone
Exclusive Economic Zone
Federal Submerged Lands
High Seas
Privately Owned
State Owned
TX
3 n. mi.
12 n. mi.
200 n. mi.
Privately Owned
State Owned
DE, MA, ME, NH, PA, VA
MHHW MHW
MLLW
IMPORTANCE OF SHORELINE
National Chart Datum
Height Modernization
-faster -cheaper
-Nearly as good
differential leveling
GNSS
HEIGHT MODERNIZATION- USING GPS FOR HEIGHTS
CHA – CHING $$$$$$$ ♪♪♪
Level Surfaces and Orthometric Heights
Level Surfaces
Plumb Line
“Geoid”
PO
P
Level Surface = Equipotential Surface (W)
H (Orthometric Height) = Distance along plumb line (PO to P)
Ocean
Local Mean Sea Level
W
W
LEVELED HEIGHT VS. ORTHOMETRIC HEIGHT
20
HC HA
∆HAC ≠ ∆hAB + ∆hBC
Observed difference in orthometric height, ∆H, depends on the leveling route.
A C
B Topography
∆ hAB
∆ h = local leveled differences
= ∆ hBC
∆H = relative orthometric heights
You cannot currently achieve orthometric heights to national standards,
1st, 2nd, or 3rd-Order with GPS observations
WHAT YOU CAN’T DO WITH GPS HEIGHTS
GEODETIC LEVELING ACCURACY STANDARDS
CLASSIFICATION MAXIMUM ELEV. DIFFERENCE ACCURACY
FIRST - CLASS I 0.5 mm √Km
FIRST - CLASS II 0.7 mm √Km
SECOND – CLASS I 1.0 mm √Km
SECOND – CLASS II 1.3 mm √Km
THIRD 2.0 mm √Km
(NOTE: REMEMBER THAT THERE ARE PROCEDURES AND EQUIPMENT SPECIFICATIONS TO FOLLOW FOR THESE CLASSES AS WELL)
EXAMPLE
2nd- Order Class 2 = 1.3 mm x √ k For a 10 km / 6.2 mi line
= 1.3 mm x √ 10 = 1.3 mm x 3.162
= 4 mm / 0.01 ft (95% confidence)
FEDERAL GEODETIC CONTROL SUBCOMMITTEE STANDARDS AND SPECIFICATIONS FOR GEODETIC CONTROL NETWORKS
1984
Macrometer V-1000 GPS Receiver 1982 ~ appox. $250,000 each
Where are we now??
February 22, 1978 - 1st NAVSTAR Satellite launched July 17, 1995 - System Fully Operational May 1, 2000 - Selective Availability turned off September 26, 2005 - L2C band added May 28, 2010 - First L5 Satellite added Mid 2014 – First Block III scheduled for launch 2020? - 10-50 cm real-time accuracy!
Global Positioning System
GPS Block I GPS Block II GPS Block III
Four positioning and navigation systems NAVSTAR/GPS – US (Currently 31) GLONASS – Russia (Currently 24)
GALILEO – EU (Currently 4, 30 by 2019) BEIDOU – China (30+ by 2020?)
Russia - GLONASS US - GPS EU - Galileo China – BeiDou
Global Navigation Satellite System
PRECISE ORTHOMETRIC HEIGHTS FROM GPS ARE MUCH HARDER TO ACHIEVE THAN HORIZONTAL POSITIONS
SOME REASONS: SATELLITE GEOMETRY LIMITED TO ZENITH ONLY
ATMOSPHERIC EFFECTS ON THE GNSS SIGNAL CAUSE GREATER UNCERTAINTY IN
THE VERTICAL
ANTENNA PHASE CENTER VARIATION AFFECTS THE VERTICAL MORE
BROADCAST/ ULTRA-RAPID/RAPID ORBITS IMPACT HEIGHTS MORE THAN HORIZONTAL ERRORS IN EACH COMPONENT OF THE: H = h – N ACCUMULATE
1. GPS ELLIPSOID HEIGHT
2. A SOURCE OF ORTHOMETRIC HEIGHT TRUTH (PASSIVE MARKS FOR NAVD 88, ARPs FOR NAVD 22)
3. A MODEL TO PROVIDE A SEPARATION DISTANCE FROM THE REFERENCE ELLIPSOID TO THE “ELEVATION” DATUM SURFACE- CALLED A “GEOID HEIGHT”.
GPS-DERIVED HEIGHTS RELY ON THREE ELEMENTS
-
GEODETIC DATUM= •SURFACE
•ORIENTATION •SCALE
•ORIGIN + GRAVITY
Z
Y X
-Z
-X -Y
Zero Meridian
Mean Equatorial Plane
X
Z
Y
Earth-Centered Earth-Fixed
(ECEF) Coordinate System
Earth Mass Center
Conventional Terrestrial Pole 1984.0
Bureau International de l'Heure (BIH) now the IERS
-X -Y
-Z
X, Y, Z = 0
XA, YA,ZA
3-D Coordinates derived from GPS
YA
X
Z
Y
A
XA
+ZA
Equator
Earth Mass Center
- X
- Y
- Z
X1 Y1 Z1
X2 Y2 Z2
X3 Y3 Z3
X4 Y4 Z4
XA YA ZA
NA EA hA
+ Geoid Model + NA EA HA
λA hA
φA
λA HA
φA
SPC/UTM
OPUS
OPUS-RS $$ Receivers
15 Minutes of data Results not shared
OPUS-DB $$ Receivers
4 Hours of data Results shared
OPUS-S $$ Receivers
2 Hours of data Results not shared
LOCUS (Leveling Online Computing User Service)
Digital Bar-Code Leveling Integration with GPS? Results shared or not?
FLAVORS OF OPUS
OPUS-PROJECTS $$ Receivers
2-4 Hours of data Multiple Receivers Network Solution
Coming Soon ~ Fall ‘13
WHAT DOES OPUS OUTPUT LOOK LIKE? NGS OPUS SOLUTION REPORT ======================== All computed coordinate accuracies are listed as peak-to-peak values. For additional information: http://www.ngs.noaa.gov/OPUS/about.jsp#accuracy USER: base9geodesy@gmail.com DATE: August 07, 2013 RINEX FILE: york212m.13o TIME: 21:25:23 UTC SOFTWARE: page5 1209.04 master42.pl 072313 START: 2013/07/31 12:00:00 EPHEMERIS: igr17513.eph [rapid] STOP: 2013/07/31 14:00:00 NAV FILE: brdc2120.13n OBS USED: 5247 / 5463 : 96% ANT NAME: TRM33429.00+GP NONE # FIXED AMB: 42 / 42 : 100% ARP HEIGHT: 0.000 OVERALL RMS: 0.015(m) REF FRAME: NAD_83(2011)(EPOCH:2010.0000) IGS08 (EPOCH:2013.5796) X: 1122459.228(m) 0.010(m) 1122458.414(m) 0.010(m) Y: -4763243.010(m) 0.007(m) -4763241.571(m) 0.007(m) Z: 4076945.542(m) 0.007(m) 4076945.479(m) 0.007(m) LAT: 39 59 13.27644 0.004(m) 39 59 13.30795 0.004(m) E LON: 283 15 35.46292 0.012(m) 283 15 35.44343 0.012(m) W LON: 76 44 24.53708 0.012(m) 76 44 24.55657 0.012(m) EL HGT: 99.616(m) 0.007(m) 98.359(m) 0.007(m) ORTHO HGT: 133.337(m) 0.018(m) [NAVD88 (Computed using GEOID12A)] UTM COORDINATES STATE PLANE COORDINATES UTM (Zone 18) SPC (3702 PA S) Northing (Y) [meters] 4427766.779 73075.174 Easting (X) [meters] 351429.243 686248.814 Convergence [degrees] -1.11844862 0.65518429 Point Scale 0.99987174 0.99999204 Combined Factor 0.99985611 0.99997641 US NATIONAL GRID DESIGNATOR: 18SUK5142927766(NAD 83) BASE STATIONS USED PID DESIGNATION LATITUDE LONGITUDE DISTANCE(m) DL3184 LOYR LOYOLA R CORS ARP N393408.726 W0755914.994 79440.3 DM4139 PAFC CHAMBERSBURG CORS ARP N395649.413 W0774011.167 79546.7 DF6305 UMBC U OF MD BALT COOP CORS ARP N391524.360 W0764241.468 81116.0 NEAREST NGS PUBLISHED CONTROL POINT DE8103 YORK CORS ARP N395913.276 W0764424.537 0.0 This position and the above vector components were computed without any knowledge by the National Geodetic Survey regarding the equipment or field operating procedures used.
PUBLISHED 39 59 13.27663 - (0.006 m) 76 44 24.53717 - (0.002 m) 99.616 m - .000
HOW GOOD ARE OPUS ORTHOMETRIC HEIGHTS?
IT DEPENDS!
ORTHOMETRIC HEIGHT ~ 0.02 – 0.04 m GEOID12A ~ 0.04 – 0.06 m (2 sigma – 95% confidence)
Combined Errors ~ 0.03 + 0.05 ~ 0.08 m / 0.3 ft
north east up
RMS values (cm) along the n, e, and u components for each point and T
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
7.50
8.00
8.50
9.00
1 2 3 4
centim
ete
rs
GODE
MBWWMIA3
SLAI
TCUN
PRED
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
7.50
8.00
8.50
9.00
1 2 3 4
centim
ete
rs
GODE
MBWWMIA3
SLAI
TCUN
PRED
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
10.00
11.00
12.00
13.00
1 2 3 4
centim
ete
rs
GODE
MBWWMIA3
SLAI
TCUN
PRED
1;( )
3.7;k horizontalkRMS cmk verticalT=
= =
OPUS Accuracy
What is “THE” Geoid?
The equipotential surface of the Earth’s gravity field which best fits, in the least squares sense, global mean sea level
Gravimetric (or Gravity) Geoid Height Models (e.g. USGG2012, USGG2009)
Defined by gravity data crossing the geoid Refined by terrain models (DEM’s) Scientific and engineering applications
Composite (or Hybrid) Geoid Height Models
(e.g. GEOID12A, GEOID09) Starts with gravimetric geoid Warped to fit available GPSBM control data Defined by legislated ellipsoid (NAD 83) and local vertical datum (NAVD 88, PRVD02, etc.) May be statutory for some surveying & mapping applications
Types and Uses of Geoid Height Models
• Gravimetric Geoid systematic misfit to BM’s but best fits “true” heights • Hybrid Geoid “converted” to fit local BM’s, so best fits NAVD 88 heights • Conversion Surface model of systematic misfit derived from BM’s in IDB
Earth’s Surface
h h
h h h
H H
H H
H
N N N N
N
Ellipsoid
Hybrid Geoid 12A
Hybrid Geoid Models (e.g. GEOID12A), Gravimetric Geoid Model (e.g. USGG2012) and conversion surface using GPS on NAVD 88 Bench Marks in NSRS
GPSBM1999: 6,169 total 0 Canada STDEV 9.2 cm (2σ) GPSBM2003: 14,185 total 579 Canada STDEV 4.8 cm (2σ) GPSBM2009: 18,291 total 576 Canada STDEV 2.8 cm (2σ)
DISTRIBUTION OF GPSBM IN GEOID12A
GEOID 12A Accuracy in Oregon Map Currently only available in DSWorld
Comparison of 30 Minute Solutions - Precise Orbit; Hopfield (0); IONOFREE(30 Minute solutions computed on the hour and the half hour)
MOLA to RV22 10.8 Km
Day 264dh (m)
Hours Diff. Day 265
dh (m)
Day 264 minus
Day 265 (cm)
* diff >2 cm
Mean dh (m)
Mean dh minus "Truth" (cm)
* diff >2 cm
14:00-14:30 -10.281 27hrs 17:00-17:30 -10.279 -0.2 -10.280 -0.514:30-15:00 -10.278 27hrs 17:30-18:00 -10.270 -0.8 -10.274 0.215:00-15:30 -10.281 27hrs 18:00-18:30 -10.278 -0.3 -10.280 -0.415:30-16:00 -10.291 27hrs 18:30-19:00 -10.274 -1.7 -10.283 -0.716:00-16:30 -10.274 27hrs 19:00-19:30 -10.274 0.0 -10.274 0.216:30-17:00 -10.287 27hrs 19:30-20:00 -10.276 -1.1 -10.282 -0.617:00-17:30 -10.279 27hrs 20:00-20:30 -10.261 -1.8 -10.270 0.617:30-18:00 -10.270 27hrs 20:30-21:00 -10.251 -1.9 -10.261 1.518:00-18:30 -10.277 21hrs 15:00-15:30 -10.270 -0.7 -10.274 0.218:30-19:00 -10.271 21hrs 15:30-16:00 -10.276 0.5 -10.274 0.219:00-19:30 -10.277 21hrs 16:00-16:30 -10.278 0.1 -10.278 -0.219:30-20:00 -10.271 21hrs 16:30-17:00 -10.286 1.5 -10.279 -0.320:00-20:30 -10.259 18hrs 14:00-14:30 -10.278 1.9 -10.269 0.720:30-21:00 -10.254 18hrs 14:30-15:00 -10.295 4.1 * -10.275 0.1
"Truth"14:00-21:00 -10.275 14:00-21:00 -10.276 0.1 -10.276
Two Days/Same Time
-10.254 -10.251 > -10.253
Difference = 0.3 cm
“Truth” = -10.276 Difference = 2.3 cm
Two Days/ Different Times
-10.254 -10.295 > -10.275
Difference = 4.1 cm
“Truth” = -10.276
Difference = 0.1 cm
• 80,000 PASSIVE MARKS (FROM GPS CAMPAIGNS) • UPDATES POSITIONS BASED ON MULTI-YEAR CORS NAD 83
(2011) ADJUSTMENT • NAD 83 (2011) ELLIPSOID HEIGHTS ARE NOT COMPATIBLE
WITH GEOID 09 • GEOID 12A DEVELOPED FOR USE WITH NAD 83 (2011)
ELLIPSOID HEIGHTS
• UPDATED BY 8 YEARS (2002 T0 2010) • VELOCITIES BETTER KNOWN AT A MORE RECENT EPOCH • ABSOLUTE ANTENNA CALIBRATIONS (OLD = RELATIVE) • BASED ON IGS (2008) EPOCH 2005.0 [OLD WAS ITRF
(2000) EPOCH 1997]
AJ8186 *********************************************************************** AJ8186 DESIGNATION - LINDQUIST AJ8186 PID - AJ8186 AJ8186 STATE/COUNTY- OR/CLACKAMAS AJ8186 COUNTRY - US AJ8186 USGS QUAD - BEDFORD POINT (1997) AJ8186 AJ8186 *CURRENT SURVEY CONTROL AJ8186 ______________________________________________________________________ AJ8186* NAD 83(2011) POSITION- 45 11 42.82165(N) 122 14 12.73862(W) ADJUSTED AJ8186* NAD 83(2011) ELLIP HT- 589.951 (meters) (06/27/12) ADJUSTED AJ8186* NAD 83(2011) EPOCH - 2010.00 AJ8186* NAVD 88 ORTHO HEIGHT - 612.2 (meters) 2009. (feet) GPS OBS AJ8186 ______________________________________________________________________ AJ8186 NAVD 88 orthometric height was determined with geoid model GEOID99 AJ8186 GEOID HEIGHT - -22.20 (meters) GEOID99 AJ8186 GEOID HEIGHT - -22.21 (meters) GEOID12A AJ8186 NAD 83(2011) X - -2,401,800.839 (meters) COMP AJ8186 NAD 83(2011) Y - -3,808,557.337 (meters) COMP AJ8186 NAD 83(2011) Z - 4,503,082.514 (meters) COMP AJ8186 LAPLACE CORR - 2.72 (seconds) DEFLEC12A AJ8186 AJ8186 FGDC Geospatial Positioning Accuracy Standards (95% confidence, cm) AJ8186 Type Horiz Ellip Dist(km) AJ8186 ------------------------------------------------------------------- AJ8186 NETWORK 0.87 2.43 AJ8186 ------------------------------------------------------------------- AJ8186 MEDIAN LOCAL ACCURACY AND DIST (024 points) 1.08 2.99 39.53 AJ8186 ------------------------------------------------------------------- AJ8186 NOTE: Click here for information on individual local accuracy AJ8186 values and other accuracy information. AJ8186 AJ8186 AJ8186.The horizontal coordinates were established by GPS observations AJ8186.and adjusted by the National Geodetic Survey in June 2012. AJ8186 AJ8186.NAD 83(2011) refers to NAD 83 coordinates where the reference AJ8186.frame has been affixed to the stable North American tectonic plate. See AJ8186.NA2011 for more information. AJ8186 AJ8186.The horizontal coordinates are valid at the epoch date displayed above AJ8186.which is a decimal equivalence of Year/Month/Day. AJ8186 AJ8186.The orthometric height was determined by GPS observations and a AJ8186.high-resolution geoid model. AJ8186 AJ8186.The ellipsoidal height was determined by GPS observations AJ8186.and is referenced to NAD 83.
Identified as Height Mod
survey station
OPUS-DB POINT POSITIONING, BUT A REPLACEMENT FOR BLUEBOOKING
OPUS-DB ALLOWS USERS TO PUBLISH THEIR OPUS RESULT IN AN ON-LINE DATA BASE IF MINIMUM REQUIREMENTS FOR QUALITY ARE MET AND THE ASSOCIATED META-DATA, SUCH AS PHOTOS AND DESCRIPTIONS, ARE PROVIDED
NOAA Technical Memorandum NOS NGS-58
GUIDELINES FOR ESTABLISHING GPS-DERIVED ELLIPSOID HEIGHTS(STANDARDS: 2 CM AND 5 CM)VERSION 4.3
David B. ZilkoskiJoseph D. D'OnofrioStephen J. Frakes
Silver Spring, MD
November 1997
U.S. DEPARTMENT OF National Oceanic and National Ocean National GeodeticCOMMERCE Atmospheric Administration Service Survey
Available “On-Line” at the NGS Web Site:
www.ngs.noaa.gov
SEARCH: “NGS 58”
Guidelines for Establishing GPS-Derived Orthometric
Heights (Standards: 2 cm and 5 cm)
http://www.ngs.noaa.gov/
SEARCH: “NGS 59”
SOME FINAL THOUGHTS: GEODETIC DIGITAL LEVELING IS STILL THE MOST PRECISE WAY TO PERFORM ORTHOMETRIC HEIGHT TRANSFERS. NAVD 88 IS BASED UPON PHYSICAL BENCH MARKS THAT ESSENTIALLY HAVE UNKNOWN ACCURACY SINCE THE LAST TIME THEY WERE VERIFIED. NAVD 88 CAN BE PROMULGATED USING GNSS TECHNOLOGY WITH VARYING ACCURACY THAT CAN APPROACH 3RD-ORDER GEODETIC LEVELING PRECISION.
GOOD COORDINATION BEGINS WITH GOOD COORDINATES
GEOGRAPHY WITHOUT GEODESY IS A FELONY