GPS-DERIVED HEIGHTS - PLSO Doyle GPS-DERIVE... · GPS-DERIVED HEIGHTS . ELLIPSOID ... (Latitude and Longitude) (e.g. U.S. Standard Datum, NAD 27, NAD 83 ... Coordinates seldom change

PROFESSIONAL LAND SURVEYORS OF OREGON SALEM

JANUARY 23, 2014

Dave Doyle Base 9 Geodetic Consulting Services National Geodetic Survey (Retired)

[email protected]

GPS-DERIVED HEIGHTS

mailto:[email protected]�

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

Presenter

Presentation Notes

a consistent, accurate, up-to-date National Shoreline; .the National CORS, a set of Global Positioning System (GPS) Continuously Operating Reference Stations meeting NOAA geodetic standards for installation, operation, and data distribution; .a network of permanently marked geodetic control points; and .a set of accurate models describing dynamic geophysical processes affecting spatial measurements.

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

Presenter

Presentation Notes

State define boundaries by statute which varies around the United States. Changes in sea level will affect these boundaries.

Presenter

Presentation Notes

Begin our understanding of orthometric heights. Heights & Datums - traditionally orthometric heights meant above sea level. Now we must be aware of factors affecting our understanding and use of height interpretations. Determining elevation differences through use of conventional leveling procedures. Conventional spirit-leveled height from points A to B and B to C. Differential leveling surveys, being a “piecewise” metric measurement technique, accumulate local height differences (dh).

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

Presenter

Presentation Notes

Level surfaces - imagine earth standing still - ocean standing still; no effects such as currents, tides, winds; except for slight undulations created by gravity effects = level surface. Geoid is this level surface relating to today’s mean sea level surface - this does not truly coincide with mean sea level because of the non-averaging effects of currents, tides, water temperatures, salinity, weather, solar/lunar cycle, etc. The geoid is a best fit mean sea level surface. Equipotential surfaces - add or subtract water and level surface changes parallel to previous surface = infinite number of possible level surfaces. Each equipotential surface has one distinct potential quantity along its surface. Point on earth’s surface is the level surface parallel to the geoid achieved by adding or subtracting potential. Lines don’t appear parallel; they are based on the gravity field and are affected by mass pluses and minuses. Geopotential number is the numerical difference between two different equipotential surfaces. W = potential along a level surface. CP = geopotential number at a point. Plumb line (over exaggerated in drawing) - is a curved distance due to effects of direction of gravity- known as deflection of the vertical. Orthometric height is exactly the distance along this curved plumb line between the geoid and point on the earth’s surface. We can make close approximations but to be exact we would need to measure gravity along this line requiring a bored hole which is impractical.

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

Presenter

Presentation Notes

Combining what we’ve discussed. For illustration, let’s assume the same equipotential (level) surface runs through points A and C. As discussed, there are an infinite number of level surfaces; another illustrated through point B. Conventional spirit-leveled height from points A to B and B to C. Differential leveling surveys, being a “piecewise” metric measurement technique, accumulate local height differences (dh). Leveled height difference from point A to B equals the leveled height difference from point B to C; (dhAB) = (dhBC). The sum of these leveled differences is not, however, equal to the difference in orthometric height (dH) between two bench marks A and C. This is due to the non-parallelism of level surfaces (dHAC) (dhAB) + (dhBC). The difference between leveled height (dhAC) and relative orthometric height (dHAC) is orthometric correction. The difference is usually greater in mountainous regions where level surfaces exhibit much greater local warping due to more pronounced changes in local gravity. The orthometric height is determined by the distance along the plumb line from the reference surface (Geoid) to the point.

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

Presenter

Presentation Notes

GPS Coordinate System - works with X, Y, Z coordinate frame based on center of mass Earth-Centered-Earth-Fixed (ECEF) coordinate system; changed into ellipsoidal latitude, longitude, and height through transformation. Cartesian Coordinate System.

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

Presenter

Presentation Notes

OPUS Database Stream-lined method for users to publish their results User registration - ID & password, Validation process, OPUS solutions can be integrated into the NGS database Data elements from OPUS , Additional metadata Submission review by user and NGS OPUS Projects Managers can define a project Process any number of stations under a project, Project can span several days to weeks, Contract work Project processing Each dataset sent to OPUS but identified with a project, Results returned to submitter a few minutes later, Manager can monitor processing and submission Final adjustment Entire project adjusted as one campaign, Review & submission to NGS OPUS Rapid Static User requests, Single frequency capability, Rapid static solutions (10 – 15 minutes of data), Will be processed with carrier phases Accurate to several centimeters, Need more accurate ionospheric and tropospheric modeling In development at OSU and NGS OPUS GIS Compute a differential pseudorange solution for less expensive GPS receivers Aimed at the GIS community who do not require cm level accuracies Allows processing in a consistent approach and “certify” their locations in the NSRS Generate rapid static solution from seconds or minutes of data Accuracies: A few decimeters to a meter horizontally Pilot project underway in Phoenix, Arizona

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: [email protected] 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

Presenter

Presentation Notes

This is what your email will look like.

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)

Presenter

Presentation Notes

These are the control data used to make xGEOID06a, GEOID03 and GEOID99 (GPS on bench marks: GPSBM’s). Improvements in Distribution are primarily due to obtaining data in Canada. The bulk of the increase comes in one state: Minnesota (603 => 4161). Note the inequitable distribution. You could practically grid the GPSBM’s in South Carolina or Minnesota and get a good result. Other places are not so fortunate… Also note that this shows distribution but not quality of the points. Some regions (e.g., Texas) have systematic quality problems (due to subsidence) that impact the GPSBM’s and the derived hybrid geoids. Current techniques rely on creating models of the systematic effects at multiple wavelengths. If the spatial density doesn’t support the shorter wavelength models, then the quality of predictions will commensurately be reduced. Note that a hyper-dense survey isn’t necessary to achieve optimal results. Later discussion on Minnesota will emphasize this.

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

Presenter

Presentation Notes

Dh is computed for a series of 30 minute sessions over 2 days and the average dh is found Taking the observation from the same time each day (when the satellite geometry is similar), the difference in the dh is only .3 cm, but the difference from the average is 2.3 cm. Now if you take the dh from different times on the 2 days (different geometry), the difference between the 2 vectors is 4.1 cm, but the difference from the average is only .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

Presenter

Presentation Notes

Following NGS guidelines, achieving 2 cm or 5 cm accuracy, and submitting the project to NGS will get NAVD88 orthometric elevations published to centimeters. Metadata will define the method of determination as that done by GPS observations using a high resolution geoid model using precise GPS observations and processing techniques.

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”

Presenter

Presentation Notes

Guidelines - will eventually become routine; not so much explanation of why its done but provides background information. Repeat baselines, station spacing, fixed height antenna setups, identify and control all error sources, tie local networks together, etc.. NOS NGS-58 GPS-Derived Ellipsoid Heights Guidelines will lay the foundation for GPS-Derived Orthometric Heights Guidelines. Produce 2 cm ellipsoid heights to be able to obtain 2 cm orthometric heights.

Guidelines for Establishing GPS-Derived Orthometric

Heights (Standards: 2 cm and 5 cm)

http://www.ngs.noaa.gov/

SEARCH: “NGS 59”

Presenter

Presentation Notes

Guidelines - will eventually become routine; not so much explanation of why its done but provides background information. Repeat baselines, station spacing, fixed height antenna setups, identify and control all error sources, tie local networks together, etc.. GPS-Derived Orthometric Heights Guidelines will build from the NOS NGS-58 GPS-Derived Ellipsoid Heights Guidelines. Similar format, many similar appendices, etc.

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

Documents

GPS-DERIVED HEIGHTS - PLSO Doyle GPS-DERIVE... · GPS-DERIVED HEIGHTS . ELLIPSOID ... (Latitude and Longitude) (e.g. U.S. Standard Datum, NAD 27, NAD 83 ... Coordinates seldom change