GPS-DERIVED HEIGHTS PROFESSIONAL LAND SURVEYORS OF OREGON SALEM JANUARY 23, 2014

Transcription

1 GPS-DERIVED HEIGHTS PROFESSIONAL LAND SURVEYORS OF OREGON SALEM JANUARY 23, 2014 Dave Doyle Base 9 Geodetic Consulting Services National Geodetic Survey (Retired) base9geodesy@gmail.com

2 ELLIPSOID - GEOID RELATIONSHIP H = Orthometric Height (NAVD 88) h = Ellipsoid Height (NAD 83 (2011)) N = Geoid Height (GEOID12A) H h H = h N Geoid Mean Sea Level N Geoid Model Ellipsoid GRS80

3 MONUMENTS IN THE GROUND ANTENNAS IN THE AIR

4 HOW ARE ACCURATE HEIGHTS MEASURED? LEVELING (mm accuracy) (very expensive, time consuming, highly trained personnel) And/Or GNSS (several cm accuracy) (cheaper, quicker, fewer trained personnel)

5 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)

6 NATIONAL SPATIAL REFERENCE SYSTEM(NSRS) Consistent National Coordinate System Latitude Longitude Height Scale Gravity Orientation and how these values change with time

7 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 Tools -Models of geophysical effects on spatial measurements -e.g., NADCON, INVERSE, SPCS83, UTMS, FORWARD

8 SUBSIDENCE: 10 MM/YEAR TO OVER 27 MM/YR

9 WHEN WAS THE PASSIVE MARK ACCESSED?

10 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, 1 st, 2 nd, 3 rd, 3cm,.02 ft, Scaled

11 GEOSPATIAL DATA REQUIRES METADATA! 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

12 N E H PT 1, , , ,HOLE 2, , , ,MHSS 3, , , ,MHSS 4, , , ,MHSS 5, , , ,PKNL 6, , , ,DOT 7, , , ,PIPE 8, , , ,MONU 9, , , ,MONU 10, , , ,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

13 TYPES OF HEIGHTS ORTHOMETRIC The distance between the geoid and a point on the Earths surface measured along the plumb line. (From Leveling cm / ft) GEOID The distance along a perpendicular from the ellipsoid of reference to the geoid (From Model 1-5 cm / ft) ELLIPSOID The distance along a perpendicular from the ellipsoid to a point on the Earth s surface. (From GNSS Observations 1-5 cm / ft)

14 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.)

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16 IMPORTANCE OF SHORELINE AL, AK, CA, CT, FL, GA, LA, MD, MS, NJ, NY, NC, OR, RI, SC, WA Privately Owned State Owned Uplands Tidelands Territorial Seas Contiguous Zone MHHW State Submerged Lands 3 n. mi. MHW MLLW Exclusive Economic Zone Federal Submerged Lands High Seas 12 n. mi. 200 n. mi. National Chart Datum Privately Owned TX State Owned Privately Owned State Owned DE, MA, ME, NH, PA, VA

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18 HEIGHT MODERNIZATION- USING GPS FOR HEIGHTS Height Modernization -faster -cheaper -Nearly as good differential leveling CHA CHING $$$$$$$ GNSS

19 Level Surfaces and Orthometric Heights Level Surfaces P W Local Mean Sea Level Plumb Line Geoid W P O Ocean Level Surface = Equipotential Surface (W) H (Orthometric Height) = Distance along plumb line (P O to P)

20 LEVELED HEIGHT VS. ORTHOMETRIC HEIGHT B Topography A h AB = h BC C H A H AC h AB + h BC H C h = local leveled differences H = relative orthometric heights Observed difference in orthometric height, H, depends on the leveling route. 20

21 WHAT YOU CAN T DO WITH GPS HEIGHTS You cannot currently achieve orthometric heights to national standards, 1 st, 2 nd, or 3 rd -Order with GPS observations

22 GEODETIC LEVELING ACCURACY STANDARDS CLASSIFICATION FIRST - CLASS I FIRST - CLASS II SECOND CLASS I SECOND CLASS II THIRD MAXIMUM ELEV. DIFFERENCE ACCURACY 0.5 mm Km 0.7 mm Km 1.0 mm Km 1.3 mm Km 2.0 mm Km (NOTE: REMEMBER THAT THERE ARE PROCEDURES AND EQUIPMENT SPECIFICATIONS TO FOLLOW FOR THESE CLASSES AS WELL)

23 FEDERAL GEODETIC CONTROL SUBCOMMITTEE STANDARDS AND SPECIFICATIONS FOR GEODETIC CONTROL NETWORKS 1984 EXAMPLE 2 nd - 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 = 4 mm / 0.01 ft (95% confidence)

24 Macrometer V-1000 GPS Receiver 1982 ~ appox. $250,000 each

25 Where are we now??

26 Global Positioning System GPS Block I GPS Block II GPS Block III February 22, st NAVSTAR Satellite launched July 17, System Fully Operational May 1, Selective Availability turned off September 26, L2C band added May 28, First L5 Satellite added Mid 2014 First Block III scheduled for launch 2020? cm real-time accuracy!

27 Global Navigation Satellite System US - GPS Russia - GLONASS EU - Galileo China BeiDou 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?)

28 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

29 GPS-DERIVED HEIGHTS RELY ON THREE ELEMENTS 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.

30 Zero Meridian -Y - Z -X GEODETIC DATUM= SURFACE ORIENTATION SCALE ORIGIN + GRAVITY X Mean Equatorial Plane Y -Z

31 Earth-Centered Earth- Fixed (ECEF) Coordinate System Z X A, Y A,Z A X -Y Conventional Terrestrial Pole Bureau International de l'heure (BIH) now the IERS Earth Mass Center X, Y, Z = 0 -X Y -Z

32 3-D Coordinates derived from GPS X 1 Y 1 Z 1 X 2 Y 2 Z 2 X 3 Y 3 Z 3 SPC/UTM Z X 4 Y 4 Z 4 - Y Earth Mass Center A +Z A X A Y A Z A φ A λ A h A N A E A h A + Geoid Model + X Equator Y A - Z X A - X Y φ A λ A H A N A E A H A

33 OPUS-S $$ Receivers 2 Hours of data Results not shared OPUS-RS $$ Receivers 15 Minutes of data Results not shared FLAVORS OF OPUS OPUS OPUS-PROJECTS $$ Receivers 2-4 Hours of data Multiple Receivers Network Solution Coming Soon ~ Fall 13 OPUS-DB $$ Receivers 4 Hours of data Results shared LOCUS (Leveling Online Computing User Service) Digital Bar-Code Leveling Integration with GPS? Results shared or not?

34 WHAT DOES OPUS OUTPUT LOOK LIKE? NGS OPUS SOLUTION REPORT ======================== All computed coordinate accuracies are listed as peak-to-peak values. For additional information: USER: DATE: August 07, 2013 RINEX FILE: york212m.13o TIME: 21:25:23 UTC SOFTWARE: page master42.pl START: 2013/07/31 12:00:00 EPHEMERIS: igr17513.eph [rapid] STOP: 2013/07/31 14:00:00 NAV FILE: brdc n OBS USED: 5247 / 5463 : 96% ANT NAME: TRM GP NONE # FIXED AMB: 42 / 42 : 100% ARP HEIGHT: OVERALL RMS: 0.015(m) PUBLISHED (0.006 m) REF FRAME: NAD_83(2011)(EPOCH: ) IGS08 (EPOCH: ) HOW 76 GOOD X: (m) ARE OPUS 0.010(m) - (0.002 ORTHOMETRIC m) HEIGHTS? (m) 0.010(m) Y: (m) 0.007(m) (m) 0.007(m) Z: (m) m 0.007(m) (m) 0.007(m) IT DEPENDS! LAT: (m) (m) E LON: (m) (m) W LON: (m) (m) EL HGT: (m) 0.007(m) (m) 0.007(m) ORTHO HGT: (m) 0.018(m) [NAVD88 (Computed using GEOID12A)] ORTHOMETRIC HEIGHT ~ m GEOID12A ~ m (2 sigma 95% confidence) Combined Errors ~ UTM COORDINATES STATE PLANE COORDINATES UTM (Zone 18) SPC (3702 PA S) Northing (Y) [meters] Easting (X) [meters] Convergence [degrees] Point Scale ~ 0.08 m / ft Combined Factor US NATIONAL GRID DESIGNATOR: 18SUK (NAD 83) BASE STATIONS USED PID DESIGNATION LATITUDE LONGITUDE DISTANCE(m) DL3184 LOYR LOYOLA R CORS ARP N W DM4139 PAFC CHAMBERSBURG CORS ARP N W DF6305 UMBC U OF MD BALT COOP CORS ARP N W NEAREST NGS PUBLISHED CONTROL POINT DE8103 YORK CORS ARP N W 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.

35 RMS values (cm) along the n, e, and u components for each point and T OPUS Accuracy north east up k k = 1; horizontal centimeters RMS ( cm) GODE MBW W MIA3 SLAI TCUN = T k = centimeters ; 8.00 GODE MBW W MIA3 SLAI TCUN centimeters vertical GODE MBW W MIA3 SLAI TCUN 3.50 PRED 3.50 PRED 5.00 PRED

36 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

37 Types and Uses of Geoid Height Models 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

38 Hybrid Geoid Models (e.g. GEOID12A), Gravimetric Geoid Model (e.g. USGG2012) and conversion surface using GPS on NAVD 88 Bench Marks in NSRS Earth s Surface h N H h N H h N H Ellipsoid h N H h N H Hybrid Geoid 12A 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

39 GPSBM1999: 6,169 total GPSBM2003: 14,185 total GPSBM2009: 18,291 total 0 Canada STDEV 9.2 cm (2σ) 579 Canada STDEV 4.8 cm (2σ) 576 Canada STDEV 2.8 cm (2σ)

40 DISTRIBUTION OF GPSBM IN GEOID12A

41 GEOID 12A Accuracy in Oregon Map Currently only available in DSWorld

42 Comparison of 30 Minute Solutions - Precise Orbit; Hopfield (0); IONOFREE (30 Minute solutions computed on the hour and the half hour) MOLA to RV Km Day 264 dh (m) Hours Diff. Day 265 dh (m) Day 264 minus Day 265 (cm) * diff >2 cm Mean dh (m) Mean dh minus "Truth" (cm) 14:00-14: hrs 17:00-17: :30-15: hrs 17:30-18: :00-15: hrs 18:00-18: :30-16: hrs 18:30-19: :00-16: hrs 19:00-19: :30-17: hrs 19:30-20: :00-17: hrs 20:00-20: :30-18: hrs 20:30-21: :00-18: hrs 15:00-15: :30-19: hrs 15:30-16: :00-19: hrs 16:00-16: :30-20: hrs 16:30-17: :00-20: hrs 14:00-14: :30-21: hrs 14:30-15: * "Truth" 14:00-21: :00-21: * diff >2 cm Two Days/Same Time > Difference = 0.3 cm Truth = Difference = 2.3 cm Two Days/ Different Times > Difference = 4.1 cm Truth = Difference = 0.1 cm

43 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 [OLD WAS ITRF (2000) EPOCH 1997] 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

44 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 (N) (W) ADJUSTED AJ8186* NAD 83(2011) ELLIP HT (meters) (06/27/12) ADJUSTED AJ8186* NAD 83(2011) EPOCH AJ8186* NAVD 88 ORTHO HEIGHT (meters) (feet) GPS OBS AJ8186 AJ8186 NAVD 88 orthometric height was determined with geoid model GEOID99 AJ8186 GEOID HEIGHT (meters) GEOID99 AJ8186 GEOID HEIGHT (meters) GEOID12A AJ8186 NAD 83(2011) X - -2,401, (meters) COMP AJ8186 NAD 83(2011) Y - -3,808, (meters) COMP AJ8186 NAD 83(2011) Z - 4,503, (meters) COMP AJ8186 LAPLACE CORR (seconds) DEFLEC12A AJ8186 AJ8186 FGDC Geospatial Positioning Accuracy Standards (95% confidence, cm) AJ8186 Type Horiz Ellip Dist(km) AJ AJ8186 NETWORK AJ AJ8186 MEDIAN LOCAL ACCURACY AND DIST (024 points) AJ 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 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

45 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

46 NOAA Technical Memorandum NOS NGS-58 GUIDELINES FOR ESTABLISHING GPS-DERIVED ELLIPSOID HEIGHTS (STANDARDS: 2 CM AND 5 CM) VERSION 4.3 Available On-Line at the NGS Web Site: David B. Zilkoski Joseph D. D'Onofrio Stephen J. Frakes SEARCH: NGS 58 Silver Spring, MD November 1997 U.S. DEPARTMENT OF National Oceanic and National Ocean National Geodetic COMMERCE Atmospheric Administration Service Survey

47 Guidelines for Establishing GPS-Derived Orthometric Heights (Standards: 2 cm and 5 cm) SEARCH: NGS 59

48 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 3 RD -ORDER GEODETIC LEVELING PRECISION.

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