Transcript GPS Derived Heights: A Height Modernization Primer Marquette, Michigan…….January 24, 2006

GPS Derived Heights:
A Height Modernization
Primer
Marquette, Michigan…….January 24, 2006
Flint, Michigan…………..January 26, 2006
Renee Shields
National Geodetic Survey
National Oceanic and Atmospheric Administration
Height Modernization is…
…the ability
to compute
…the establishment
of accurate,
reliable heights
using GPS
technology(“sea
in conjunction
with
accurate
orthometric
level”) heights
traditional leveling, gravity,
using
GPS technology
and modern
remote
sensing information.
How to achieve accurate GPS heights
1) What types of heights are involved?
• Orthometric heights
• Ellipsoid heights
• Geoid heights
2) How are these heights defined and
related?
3) How accurately can these heights be
determined?
What is a GEODETIC DATUM?
• Geodetic Datum
– “A set of constants specifying the coordinate
system used for geodetic control, i.e., for
calculating coordinates of points on the Earth”*
– “[above] together with the coordinate system
and the set of all points and lines whose
coordinates, lengths, and directions have been
determined by measurement or calculation.”*
*Definitions from the Geodetic Glossary, September 1986
Not To Be Confused With:
• Ellipsoid
– “A closed surface, whose planar sections are
either ellipsoids or circles.”*
– Mathematical figure which helps define a
Reference Frame
– Clarke 1866, GRS80
• Reference Frame
– “A coordinate system associated with a
physical system.”*
– NSRS, ITRF
*Definitions from the Geodetic Glossary, September 1986
Horizontal Control Datum?
Horizontal Control Datum
– “A Geodetic Datum specifying the coordinate
system in which horizontal control points are
located.”
– Defined by 8 Constants
• 3 – specify the location of the origin of the coordinate system.
• 3 – specify the orientation of the coordinate system.
• 2 – specify the dimensions of the reference ellipsoid.
– NAD 27, NAD 83
*Definition from the Geodetic Glossary, September 1986
Comparison of Horizontal Datum Elements
NAD 27
ELLIPSOID
DATUM POINT
ADJUSTMENT
BEST FITTING
CLARKE 1866
a = 6,378,206.4 m
1/f = 294.9786982
Triangulation Station
MEADES RANCH, KANSAS
25k STATIONS
Several Hundred Base Lines
Several Hundred Astro Azimuths
North America
NAD 83
GRS80
a = 6,378,137. M
1/f = 298.257222101
NONE
EARTH MASS CENTER
250k STATIONS
Appox. 30k EDMI Base Lines
5k Astro Azimuths
Doppler Point Positions
VLBI Vectors
World-Wide
NAD 27 and NAD 83
Vertical Control Datum?
Vertical Control Datum
– “A Geodetic Datum specifying the system in
which vertical control points are located.” *
– A set of fundamental elevations to which other
elevations are referred
– NGVD 29, NAVD 88 – Orthometric, “Sea Level”
– Others – Cairo, Local Tidal
*Definitions from the Geodetic Glossary, September 1986
Orthometric Heights
Comparison of Vertical Datum Elements
NGVD 29
DATUM DEFINITION
NAVD 88
26 TIDE GAUGES
IN THE U.S. & CANADA
FATHER’S POINT/RIMOUSKI
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
Conventional Leveling
ROD 1
ROD 2
ROD 1
Backsight
5’
BM
100’
Foresight
Backsight
105’
HI
6’
Foresight
96’
4.5’
7.5’
INSTR
99’
INSTR
BM
Ellipsoid, Geoid, and Orthometric Heights
H = Orthometric Height (NAVD 88)
h = Ellipsoidal Height (NAD 83)
H =h-N
N = Geoid Height (GEOID 03)
h
A
Ellipsoid
GRS80
Geoid
H
TOPOGRAPHIC SURFACE
N
B
GEOID03
Gravity measurements help answer two big questions…
Earth’s
Surface
Geoid
How “high above sea
level” am I? (FEMA,
USACE, Surveying
and Mapping)
How large are near-shore
hydrodynamic processes?
(Coast Survey, CSC,
CZM)
Orthometric Ht
From Leveling
Coast
Ocean
Surface
Ellipsoid
Ellipsoid Ht
From GPS
Geoid Height
From Gravity
From
Satellite Altimetry
What is the GEOID?
• “The equipotential surface of the Earth’s gravity
field which best fits, in the least squares sense,
mean sea level.”*
• Can’t see the surface or measure it directly.
• Can be modeled from gravity data.
*Definition from the Geodetic Glossary, September 1986
In Search of the Geoid…
Courtesy of Natural Resources Canada www.geod.nrcan.gc.ca/index_e/geodesy_e/geoid03_e.html
High Resolution Geoid Models
G99SSS (Scientific Model)
• Earth Gravity Model of 1996 (EGM96)
Long Wavelength
global
• 2.6 million terrestrial, ship-borne, and
altimetric gravity measurements
Medium Wavelength
- regional
• 30 arc second Digital Elevation Data
• 3 arc second DEM for the Northwest USA
– Decimated from 1 arc second NGSDEM99
• Computed on 1 x 1 arc minute grid spacing
• GRS-80 ellipsoid centered at ITRF97 origin
Short Wavelength
- local
-
High Resolution Geoid Models
USGG2003 (Scientific Model)
• 2.6 million terrestrial, ship, and altimetric gravity
measurements
– offshore altimetry from GSFC.001 instead of KMS98
• 30 arc second Digital Elevation Data
• 3 arc second DEM for the Northwest USA
– Decimated from 1 arc second NGSDEM99
• Earth Gravity Model of 1996 (EGM96)
• Computed on 1 x 1 arc minute grid spacing
• GRS-80 ellipsoid centered at ITRF00 origin
Gravity Coverage for GEOID03
High Resolution Geoid Models
GEOID03 (vs. Geoid99)

Begin with USGG2003 model

14,185 NAD83 GPS heights on NAVD88 leveled benchmarks
(vs. 6169)

Determine national bias and trend relative to GPS/BMs

Create grid to model local (state-wide) remaining differences

ITRF00/NAD83 transformation (vs. ITRF97)

Compute and remove conversion surface from USGG2003
High Resolution Geoid Models
GEOID03 (vs. Geoid99)

Relative to non-geocentric GRS-80 ellipsoid

2.7 cm RMS nationally when compared to BM data
(vs. 4.6 cm)

RMS  50% improvement over GEOID99 (Geoid96
to 99 was 16%)
GPS on Bench
Marks in Michigan
Composite Geoids
Earth’s Surface
h
h
h
h
h
H Ellipsoid
H
H
N
N
N
H
H
N
N
Composite Geoid
0.308 M in
0.271
Traverse City –
1999 model
2003
Gravity Geoid
•
•
Gravity Geoid systematic misfit with benchmarks
Composite Geoid biased to fit local benchmarks
Sample Datasheet
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National Geodetic Survey,
Retrieval Date = DECEMBER 28, 2005
PL0314 ***********************************************************************
PL0314 DESIGNATION - V 27
PL0314 PID
- PL0314
PL0314 STATE/COUNTY- MI/GRAND TRAVERSE
PL0314 USGS QUAD
PL0314
PL0314
*CURRENT SURVEY CONTROL
PL0314 ___________________________________________________________________
PL0314* NAD 83(1994)- 44 39 02.41202(N)
085 46 04.27942(W)
ADJUSTED
PL0314* NAVD 88
257.838 (meters)
845.92
(feet) ADJUSTED
PL0314 ___________________________________________________________________
PL0314 X
335,419.145 (meters)
COMP
PL0314 Y
- -4,532,722.532 (meters)
COMP
PL0314 Z
4,459,971.520 (meters)
COMP
PL0314 LAPLACE CORR5.18 (seconds)
DEFLEC99
PL0314 ELLIP HEIGHT223.17 (meters)
(07/17/02) GPS OBS
PL0314 GEOID HEIGHT-34.68 (meters)
GEOID03
PL0314 DYNAMIC HT 257.812 (meters)
845.84 (feet) COMP
PL0314 MODELED GRAV980,508.8
(mgal)
NAVD 88
PL0314
H
h
N
Sample Datasheet
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PL0314
PL0314 HORZ ORDER - FIRST
PL0314 VERT ORDER - FIRST
CLASS II
PL0314 ELLP ORDER - FOURTH
CLASS I
PL0314
PL0314.The horizontal coordinates were established by GPS observations
PL0314.and adjusted by the National Geodetic Survey in February 1997.
PL0314
PL0314.The orthometric height was determined by differential leveling
PL0314.and adjusted by the National Geodetic Survey in June 1991.
PL0314
PL0314.The X, Y, and Z were computed from the position and the ellipsoidal ht.
PL0314
PL0314.The Laplace correction was computed from DEFLEC99 derived deflections.
PL0314
PL0314.The ellipsoidal height was determined by GPS observations
PL0314.and is referenced to NAD 83.
PL0314
PL0314.The geoid height was determined by GEOID03.
PL0314
PL0314.The dynamic height is computed by dividing the NAVD 88
PL0314.geopotential number by the normal gravity value computed on the
PL0314.Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45
PL0314.degrees latitude (g = 980.6199 gals.).
PL0314
PL0314.The modeled gravity was interpolated from observed gravity values.
PL0314
Sample Datasheet
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PL0314
PL0314.The modeled gravity was interpolated from observed gravity values.
PL0314
PL0314;
North
East
Units Scale Factor Converg.
PL0314;SPC MI C
149,194.606 5,888,865.237
MT 0.99992569
-0 59 23.3
PL0314;SPC MI C
489,483.62 19,320,424.01
iFT 0.99992569
-0 59 23.3
PL0314;UTM 16
- 4,944,883.803
597,700.224
MT 0.99971738
+0 51 57.6
PL0314
PL0314!
- Elev Factor x Scale Factor =
Combined Factor
PL0314!SPC MI C
0.99996501 x
0.99992569 =
0.99989070
PL0314!UTM 16
0.99996501 x
0.99971738 =
0.99968240
PL0314
PL0314
SUPERSEDED SURVEY CONTROL
PL0314
PL0314 ELLIP H (02/03/97) 223.19
(m)
GP(
) 4 1
PL0314 NAD 83(1986)- 44 39 02.41257(N)
085 46 04.28315(W) AD(
) 1
PL0314 NAD 83(1986)- 44 39 02.38347(N)
085 46 04.27988(W) AD(
) 3
PL0314 NAVD 88 (09/30/91) 257.84
(m)
845.9
(f) LEVELING
3
PL0314 NGVD 29 (??/??/92) 257.915 (m)
846.18
(f) ADJ UNCH
1 2
PL0314
PL0314 Superseded values are not recommended for survey control.
PL0314.NGS no longer adjusts projects to the NAD 27 or NGVD 29 datums.
PL0314
Sample Datasheet
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PL0314_U.S. NATIONAL GRID SPATIAL ADDRESS: 16TEQ9770044884(NAD 83)
PL0314_MARKER: DB = BENCH MARK DISK
PL0314_SETTING: 7 = SET IN TOP OF CONCRETE MONUMENT
PL0314_SP_SET: CONCRETE POST
PL0314_STAMPING: V 27 1930 846.176
PL0314_MARK LOGO: CGS
PL0314_MAGNETIC: N = NO MAGNETIC MATERIAL
PL0314_STABILITY: B = PROBABLY HOLD POSITION/ELEVATION WELL
PL0314_SATELLITE: THE SITE LOCATION WAS REPORTED AS SUITABLE FOR
PL0314+SATELLITE: SATELLITE OBSERVATIONS - October 24, 1992
PL0314
PL0314 HISTORY
- Date
Condition
Report By
PL0314 HISTORY
- 1930
MONUMENTED
CGS
PL0314 HISTORY
- 1951
GOOD
NGS
PL0314 HISTORY
- 1984
GOOD
NGS
PL0314 HISTORY
- 19890428 GOOD
NGS
PL0314 HISTORY
- 1990
GOOD
USPSQD
PL0314 HISTORY
- 19910701 GOOD
NGS
PL0314 HISTORY
- 19920824 GOOD
MIDT
PL0314 HISTORY
- 19921024 GOOD
MIDT
PL0314 HISTORY
- 19971029 GOOD
USPSQD
PL0314
PL0314
STATION DESCRIPTION
PL0314
PL0314'DESCRIBED BY NATIONAL GEODETIC SURVEY 1951
PL0314'IN INTERLOCHEN.
PL0314'AT INTERLOCHEN, 131 FEET EAST OF THE JUNCTION OF THE ABANDONED
PL0314'BRANCH OF THE MANISTEE AND NORTHEASTERN RAILROAD AND THE C AND
Sample Datasheet
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National Geodetic Survey,
Retrieval Date = DECEMBER 28, 2005
PL0314 ***********************************************************************
PL0314 DESIGNATION - V 27
PL0314 PID
- PL0314
PL0314 STATE/COUNTY- MI/GRAND TRAVERSE
PL0314 USGS QUAD
PL0314
PL0314
*CURRENT SURVEY CONTROL
PL0314 ___________________________________________________________________
PL0314* NAD 83(1994)- 44 39 02.41202(N)
085 46 04.27942(W)
ADJUSTED
PL0314* NAVD 88
257.838 (meters)
845.92
(feet) ADJUSTED
PL0314 ___________________________________________________________________
PL0314 X
335,419.145 (meters)
COMP
PL0314 Y
- -4,532,722.532 (meters)
COMP
PL0314 Z
4,459,971.520 (meters)
COMP
PL0314 LAPLACE CORR5.18 (seconds)
DEFLEC99
PL0314 ELLIP HEIGHT223.17 (meters)
(07/17/02) GPS OBS
PL0314 GEOID HEIGHT-34.68 (meters)
GEOID03
PL0314 DYNAMIC HT 257.812 (meters)
845.84 (feet) COMP
PL0314 MODELED GRAV980,508.8
(mgal)
NAVD 88
PL0314
NAVD88 – Ellip Ht + Geoid Ht = …
257.838 – 223.17 – 34.953 = -0.285 USGG2003
257.838 – 223.17 – 34.68 = -0.012 GEOID03
H
h
N
What’s Left?
• Leveling-Derived Orthometric Heights
• Modeled Geoid Heights
• GPS-Derived Ellipsoid Heights
Guidelines
NOAA Technical Memorandum NOS NGS-58
GUIDELINES FOR ESTABLISHING GPS-DERIVED ELLIPSOID HEIGHTS
(STANDARDS: 2 CM AND 5 CM)
VERSION 4.3
David B. Zilkoski
Joseph D. D'Onofrio
Stephen J. Frakes
Silver Spring, MD
November 1997
U.S. DEPARTMENT OF
COMMERCE
National Oceanic and
Atmospheric Administration
National Ocean
Service
National Geodetic
Survey
Available “On-Line” at
the NGS Web Site:
www.ngs.noaa.gov
GPS Error Sources
• Orbit and clock error
– Broadcast v.s. Predicted Precise v.s. Post-processed
– Clock error corrections
• Atmospheric Effects
– Ionosphere, Troposphere
• Multipath
• Height of phase center above mark
Atmosphere-based Ionospheric Delay
< 10 km
> 10 km
Multipath
h
ø
ø
Figure 1
Multipath Description
August 1987 -Ionospheric refraction and Multipath Effects in GPS Carrier Phase Observations
Yola Georgiadou and Alfred Kleusberg
IUGG XIX General Assembly Meeting, Vancouver, Canada
Components of NGS-58
• Equipment requirements
• Field Procedures/Data Collection Parameters
• Basic Control Requirements
• Processing/Analysis Procedures
Equipment Requirements
• Dual-frequency, full-wavelength GPS receiver
– Required - observations > 10 km
– Preferred - ALL observations regardless of length
• Geodetic quality antennas with ground planes
–
–
–
–
Choke ring antennas; highly recommended
Successfully modeled L1/L2 offsets and phase patterns
Use identical antenna types if possible
Corrections must be utilized by processing software when
mixing antenna types
Equipment Requirements
“Fixed” Height
Tripod
Fixed-height
tripods required
for 2 cm standard
Fixed-height poles
preferred for 5 cm
standard
Data Collection Parameters
• VDOP < 6 for 90% or longer of 30 minute session
– Shorter session lengths stay < 6 always
– Schedule travel during periods of higher VDOP
• Session lengths > 30 minutes collect 15 second data
– Session lengths < 30 minutes collect 5 second data
• Track satellites down to 10° elevation angle
• Repeat Baselines
– Different days
– Different times of day
• Detect, remove, reduce effects due to multipath and having almost
the same satellite geometry
Gg
REPEAT BASELINE DIFFERENCES BY DISTANCE
172 BASELINES - 3% Above 3 cm
Gg
REPEAT DIFFERENCES (CM)
6
gg
5
0113-H83A
4 3.1
1933-0121
3.1
6669-6666
4.9
6669-0092
4.7
0092-1933
3.1
3
2
1
0
0
5000
10000
15000
20000
25000
30000
35000
40000
BASELINE LENGTH (M)
Station pairs with large residuals, i.e., greater than 2.5 cm, also have large repeat base line
differences. NGS guidelines for estimating GPS-derived ellipsoid heights require user to
re-observe these base lines. Following NGS guidelines provides enough redundancy for
adjustment process to detect outliers and apply residual on appropriate observation, i.e., the
bad vector.
FREE ELLIPSOID HEIGHT RESIDUAL BY BASELINE
LENGTH
455 BASE LINES - 2.6% ABOVE 3 cm
7
6
0092-0039
5.1
0113-H83A
3.1
5
0092-0039
3.8
4
0114-0913
RESIDUAL (CM)
6666-6669
-4.9
3 2.6
2
1933--0121
3.1
1
0
-1
-2
-3
6666-6669
-4.9
1933-0092
-3.1
-4
-5
0038-0913
-3.7
-6
6669-0092
-6.5
0127-6294
--3.5
-7
0.0
5.0
10.0
15.0
20.0
1933-0092
-6.5
25.0
30.0
35.0
BASE LINE LENGTH (KM)
After performing minimum constraint adjustment, plot ellipsoid height
residuals (or dU residuals) and investigate all residuals greater than 2 cm.
40.0
Comparison of 30 Minute Solutions - Precise Orbit; Hopfield (0); IONOFREE
(30 Minute solutions computed on the hour and the half hour)
-10.254
> -10.253
-10.251
MOLA to RV22 10.8 Km
dh
(m)
Hours
Diff.
Day 265
27hrs
17:00-17:30
27hrs
17:30-18:00
27hrs
18:00-18:30
27hrs
18:30-19:00
27hrs
19:00-19:30
27hrs
19:30-20:00
27hrs
20:00-20:30
27hrs
20:30-21:00
21hrs
15:00-15:30
21hrs
15:30-16:00
21hrs
16:00-16:30
21hrs
16:30-17:00
18hrs
14:00-14:30
20:30-21:00
-10.281
-10.278
-10.281
-10.291
-10.274
-10.287
-10.279
-10.270
-10.277
-10.271
-10.277
-10.271
-10.259
-10.254
18hrs
14:00-21:00
-10.275
Day 264
14:00-14:30
14:30-15:00
15:00-15:30
15:30-16:00
16:00-16:30
16:30-17:00
17:00-17:30
17:30-18:00
18:00-18:30
18:30-19:00
19:00-19:30
19:30-20:00
20:00-20:30
Two Days/Same Time
dh
(m)
Day 264 *
minus diff Mean dh
Day 265 >2
(m)
(cm) cm
14:30-15:00
-10.279
-10.270
-10.278
-10.274
-10.274
-10.276
-10.261
-10.251
-10.270
-10.276
-10.278
-10.286
-10.278
-10.295
-0.2
-0.8
-0.3
-1.7
0.0
-1.1
-1.8
-1.9
-0.7
0.5
0.1
1.5
1.9
4.1
14:00-21:00
-10.276
0.1
*
-10.280
-10.274
-10.280
-10.283
-10.274
-10.282
-10.270
-10.261
-10.274
-10.274
-10.278
-10.279
-10.269
-10.275
"Truth"
-10.276
Mean dh *
minus diff
"Truth" >2
(cm) cm
-0.5
0.2
-0.4
-0.7
0.2
-0.6
0.6
1.5
0.2
0.2
-0.2
-0.3
0.7
0.1
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
Four Basic Control Requirements
•
Occupy stations with known NAVD 88 orthometric heights
• Stations should be evenly distributed throughout project
• Project areas < 20 km on a side, surround project with NAVD 88
bench marks
• i.e., minimum number of stations is four; one in each corner of
project
• Project areas > 20 km on a side, keep distances between GPSoccupied NAVD 88 bench marks to less than 20 km
• Projects located in mountainous regions, occupy bench marks at
base and summit of mountains, even if distance is less than 20 km
Sample Project
• Area: East San Francisco Bay Project
– Latitude
37° 50” N to 38° 10” N
– Longitude 121° 45” W to 122° 25” W
• Receivers Available: 5
• Standards: 2 cm GPS-Derived Heights
Primary Base Stations
38°20’N
CORS
HARN
NAVD’88 BM
New Station
D191
10CC
Primary Base Station
MART
LAKE
MOLA
122°35’W
LONGITUDE
121°40’W
GPS-Usable Stations
CORS
HARN
NAVD’88 BM
New Station
Spacing Station
Primary Base Station
Observation Sessions
38°16’N
Session F
CORS
HARN
NAVD’88 BM
New Station
Spacing Station
Session E
Session D
Primary Base Station
Session G
Session A
Session B
122°20’W
LONGITUDE
Session C
121°40’W
Independent Base Lines
38°16’N
F
CORS
HARN
NAVD’88 BM
New Station
Spacing Station
F
E
F
E
G
Primary Base Station
D
E
F
E
D
D
G
D
G
G
C
B
A
A
B
B
A
C
B
122°20’W
C
A
LONGITUDE
C
121°40’W
Processing: Five Basic Procedures
• Perform 3-D minimally constrained (free)
adjustment
• Analyze adjustment results
• Compute differences between GPS-derived
orthometric heights from free adjustment
and published NAVD88 BMs
• Evaluate differences to determine which BMs
have valid NAVD88 height values
• Perform constrained adjustment with results
from previous step
Appendix B: GPS Ellipsoid Height Hierarchy
HARN/Control Stations
(75 km) 5.5 hr 3 days different times
Primary Base
(40 km) 5.5 hr
3 days different times
Secondary Base
(15 km) 0.5 hr
2 days different times
Local Network Stations
(7 to 10 km) 0.5 hr
2 days different times
Start with CORS
Harbor Beach
Mt. Pleasant
Bayer at Saginaw
Next Level - Michigan HARN
Have good NAVD88 Control
L26235, phases 1 & 2, courtesy of
students at Ferris State University
Height Modernization Project
HARN - Average 50km,
max 75km
Primary – 20-25km,
max 40km
=
=
=
=
HARN
Primary Base Network
Secondary Base Network
Local Base Network
Secondary - Average 12-15km, max 15km
Local – Average 6-8 km, max 10km
= Existing NGS Level line
= New HMP Level line
Basic Concept of Guidelines
• Stations in local 3-dimensional network
connected to NSRS to at least 5 cm
uncertainty
• Stations within a local 3-dimensional
network connected to each other to at least
2 cm uncertainty
• Stations established following guidelines are
published to centimeters by NGS
Network / Local Accuracy
Sample Datasheet – Leveling
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AI6151
AI6151
AI6151
AI6151
AI6151
AI6151
AI6151
AI6151
AI6151*
AI6151*
AI6151
AI6151
AI6151
AI6151
AI6151
National Geodetic Survey,
Retrieval Date = NOVEMBER 25, 2003
***********************************************************************
DESIGNATION - 2K76
PID
- AI6151
STATE/COUNTY- WI/WASHINGTON
USGS QUAD
- ALLENTON (1971)
*CURRENT SURVEY CONTROL
___________________________________________________________________
NAD 83(1997)- 43 25 39.39446(N)
088 18 24.15369(W)
ADJUSTED
NAVD 88
343.002 (meters)
1125.33
(feet) ADJUSTED
___________________________________________________________________
X
137,097.884 (meters)
COMP
Y
- -4,637,622.691 (meters)
COMP
Z
4,362,336.158 (meters)
COMP
AI6151 . . .
AI6151 The orthometric height was determined by differential leveling
AI6151 and adjusted by the National Geodetic Survey in October 2000.
AI6151
Sample Datasheet - GPS
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1
National Geodetic Survey,
Retrieval Date = JUNE 7, 2004
HL0673 ***********************************************************************
HL0673 DESIGNATION - FAA 5CO0 B
HL0673 PID
- HL0673
HL0673 STATE/COUNTY- CO/LA PLATA
HL0673 USGS QUAD
- LOMA LINDA (1968)
HL0673
HL0673
*CURRENT SURVEY CONTROL
HL0673 ___________________________________________________________________
HL0673* NAD 83(1992)- 37 12 34.23430(N)
107 51 59.34354(W)
ADJUSTED
HL0673* NAVD 88
2038.7
(meters)
6689.
(feet) GPS OBS
HL0673 ___________________________________________________________________
HL0673 X
- -1,560,867.458 (meters)
COMP
HL0673 Y
- -4,842,221.299 (meters)
COMP
HL0673 Z
3,837,158.007 (meters)
COMP
HL0673. . .
HL0673 The orthometric height was determined by GPS observations and a
HL0673 high-resolution geoid model.
HL0673
Sample Datasheet – GPS Using NGS58
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OM1256
OM1256
OM1256
OM1256
OM1256
OM1256
OM1256
OM1256
OM1256*
OM1256*
OM1256
OM1256
OM1256
OM1256
CBN
DESIGNATION PID
STATE/COUNTYUSGS QUAD
-
This is a Cooperative Base Network Control Station.
CAMBRIA GPS
OM1256
WI/COLUMBIA
RANDOLPH (1980)
*CURRENT SURVEY CONTROL
___________________________________________________________________
NAD 83(1997)- 43 34 10.47581(N)
089 06 09.35995(W)
ADJUSTED
NAVD 88
303.84
(meters)
996.8
(feet) GPS OBS
___________________________________________________________________
X
72,495.418 (meters)
COMP
Y
- -4,628,194.515 (meters)
COMP
Z
4,373,750.772 (meters)
COMP
OM1256 . . .
OM1256.The orthometric height was determined by GPS observations and a
OM1256.high-resolution geoid model using precise GPS observation and
OM1256.processing techniques.
Goal Achieved?
• With the means to get more accurate
ellipsoid heights, we can now use these
ellipsoid heights on benchmarks to further
improve the geoid model.
• With the improved geoid model we can
use GPS to compute accurate orthometric
heights.
Questions?
http://www.ngs.noaa.gov/heightmod/
MichiganMarquetteAgenda.pdf
http://www.ngs.noaa.gov/heightmod/
MichiganFlintAgenda.pdf
Renee Shields
Grants Manager
N/NGS1, SSMC3
1315 East-West Highway
Silver Spring, MD 20910
301-713-3231, x116
www.ngs.noaa.gov
[email protected]