Height Mod Overview

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National Height Modernization Program
Overview Kentucky Association of Professional
Surveyors Height Modernization Seminar February
16, 2007 Renee Shields Height Modernization
Project Manager Ross Mackay Geodetic
Advisor National Geodetic Survey, NOAA
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Height Matters
Recent studies by the NOAAs NGS, in partnership
with LSU, indicate the states hurricane
evacuation routes are growing increasingly
vulnerable to coastal storm surge and
flooding. NOAA Press Release Dec. 17, 2002
Image credit AP Photo/Rick Bowmer
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River Flooding

• Feb. 14, 1884 71.1 feet -- biggest flood of
  the century residents took shelter in abandoned
  railroad cars (Mt Washington, Newtown)

• Jan. 21, 1907 65.2 feet -- The levee broke in
  Lawrenceburg, IN .. It took 750 workers to repair
  the breach (Maysville)
• Feb. 12, 1918 61.8 feet -- Flood brought ice
  floes that smashed steamboat hulls.

www.enquirer.com
4

• Jan. 26, 1937 79.9 feet -- waters of the Ohio
  leapt riverbanks ... Local damage reached 20
  million in 1937 dollars. In Ohio River towns from
  Pittsburgh to Cairo, Ill., 385 people were
  killed, 1 million were left homeless and property
  losses eclipsed the 500 million mark.
• March 7, 1945 69.2 feet -- The
  Mill Creek barrier dam
  failed, sending
  Ohio River water up the already
  flooded valley.
  Northern KY counted
  12,000 people homeless. Portsmouth
  fought a losing battle to
  erect a levee.

www.enquirer.com
5

• March 5, 1997 64.7 ft

Michael E. Keating
Glenn Hartong
Michael E. Keating
www.enquirer.com
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Height Modernization Overview

• Definition
• Background
• Benefits
• Height Modernization Guidelines
• NGS Role

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Height Modernization is

• the establishment of accurate, reliable heights
  using GNSS technology in conjunction with
  traditional leveling, gravity, and modern remote
  sensing information.

We want it to be the establishment of accurate
orthometric (sea level) heights using GNSS
technology
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Height Modernization Objective
D E F I N I T I O N
NAVD 88
NSRS

GEODETIC CONTROL
Reliable
Accurate
Cost-effective
Standardized
Legally Established
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The Roots of Height Modernization
B A C K G R O U N D

• In 1994 - First meeting held in Sacramento, CA
• Some heights in CA in error by more than a meter
• GPS could be immediately used to meet some of
  Californias requirements
• Necessary for the implementation of NAVD 88
• In 1998, 1.0 M was added to NGS budget to
  perform Height Modernization Study

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B A C K G R O U N D

• In 2000, 500K added to NGS budget for Height
  Modernization planning
• In 2001, 2.25M added to NGS budget
• to implement Height Modernization in NC
• to support the California Spatial Reference
  Center (CSRC)
• to support NGS related Height Modernization
  activities
• Also in 2001, NOAA is directed to work with LA
  and WI to assess their requirements for Height
  Modernization

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Height Modernization Appropriations (FY01-FY06)
B A C K G R O U N D
Fiscal Year Appropriations States
FY 2001 2.25 M CA, NC
FY 2002 3.75 M CA, NC, LA, WI
FY 2003 3.75 M CA, NC, LA, WI, MS
FY 2004 9.0 M CA, NC, LA, WI, MS, AL, WA, SC
FY 2005 9.6 M CA, NC, LA, WI, MS, AL, WA, TX, KY
FY 2006 9.9 M CA, NC, WI, MS, AL, SC, TX, KY, AZ
FY 2007 CR ??
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Appropriations ( in thousands)
2001 2002 2003 2004 2005 2006 2007
AL 1,989K 2,000K 1,971K
AZ 500K
CA 1,000K 1,000K 1,000K 1,000K 500K 933K
KY 500K 500K
LA 1,000K 500K 497K 497K
MS 500K 500K 600K 600K
NC 1,000K 1,000K 1,000K 993K 1,000K 933K
SC 500K 497K 467K
TX 750K 750K
WA 500K 500K
WI 500K 500K 2,989K 3,000K 3,000K
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FY06 Height Modernization - Recipients
B A C K G R O U N D
CA California Spatial Reference Center at Scripps Institution of Oceanography
NC North Carolina Department of Environmental and Natural Resources (and North Carolina AT State University)
WI Wisconsin Department of Transportation
AL Alabama Department of Revenue
MS University of Southern Mississippi
TX Texas AM University, Corpus Christi
KY Morehead State University
SC South Carolina Geodetic Survey
AZ Arizona State Land Development
NGS Height Modernization Regional Expansion - NGS Implementation
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Height Modernization Program
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What Can Height Modernization do for me?
N E E D S B E N E F I T S
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N E E D S B E N E F I T S
Measure and Monitor - Crustal Motion California
Spatial Reference Center
- Subsidence Louisiana Spatial Reference
Center, Texas Spatial Reference Center
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N E E D S B E N E F I T S
Water Management Water Levels
HGCSD
USM

• Co-locate GPS CORS at Water Level gauges
• Improve geoid model in Gulf Coast Region
• Relate geodetic and tidal vertical datums

TSRC-TxAM-Corpus Christi
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N E E D S B E N E F I T S
Floodplain Mapping North Carolina Cooperative
Technical State
MAP Modernization
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Transportation - Safety
N E E D S B E N E F I T S
Wisconsin DOT

• Improve height data
• Supplement control where marks have been
  destroyed
• Create network that can utilize GPS technologies
  (cost effective)

LSRC, TXRC - Measuring Heights Along Evacuation
Routes
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N E E D S B E N E F I T S
Mapping and GIS
Geoid modeling
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How to achieve accurate GPS heights

• What types of heights are involved?
• Orthometric heights
• Ellipsoid heights
• Geoid heights
• How are these heights defined and related?
• How accurately can these heights be determined?

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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 IGLD, Cairo, Local Tidal
• Definitions from the Geodetic
  Glossary, September 1986

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Leveling in NAVD88
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Conventional Leveling

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Ellipsoid, Geoid, and Orthometric Heights
H Orthometric Height (leveling)
H h - N
h Ellipsoidal Height (GPS)
N Geoid Height (model)

H (NAD83)
TOPOGRAPHIC SURFACE
(NAVD88) H
N
Geoid Height (GEOID03)
Ellipsoid
Geoid
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GEOIDS versus GEOID HEIGHTS

• The equipotential surface of the Earths gravity
  field which best fits, in the least squares
  sense, (global) mean sea level.
• Cant see the surface or measure it directly.
• Can be modeled from gravity data as they are
  mathematically related.
• Note that the geoid is a vertical datum surface.
• A geoid height is the height from an ellipsoidal
  datum to a geoid.
• Hence, geoid height models are directly tied to
  the geoid and ellipsoid that define them (i.e.,
  geoid height models are not interchangeable).
• Definition from the Geodetic Glossary,
  September 1986

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In Search of the Geoid
Dr. Dan Roman
Courtesy of Natural Resources Canada
www.geod.nrcan.gc.ca/index_e/geodesy_e/geoid03_e.h
tml
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High Resolution Geoid Models

• 2.6 million terrestrial, ship, and altimetric
  gravity measurements
• 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

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Composite Geoids

Earths Surface
Ellipsoid
Composite Geoid
0.831 M in Bowling Green 2003 model
0.772 M in Bowling Green 1999 model
Gravity Geoid

• Gravity Geoid systematic misfit with benchmarks
• Composite Geoid biased to fit local benchmarks

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Sample Datasheet

• GC0051 CBN - This is a Cooperative
  Base Network Control Station.
• GC0051 PACS - This is a Primary Airport
  Control Station.
• GC0051 DESIGNATION - BOWL PORT
• GC0051 PID - GC0051
• GC0051 STATE/COUNTY- KY/WARREN
• GC0051 USGS QUAD - BOWLING GREEN SOUTH
  (1993)
• GC0051
• GC0051 CURRENT SURVEY
  CONTROL
• GC0051 _________________________________________
  __________________________
• GC0051 NAD 83(1993)- 36 57 41.82528(N) 086
  25 30.08551(W) ADJUSTED
• GC0051 NAVD 88 - 162.565 (meters)
  533.35 (feet) ADJUSTED
• GC0051 _________________________________________
  __________________________
• GC0051 X - 318,174.533 (meters)
  COMP
• GC0051 Y - -5,092,731.546 (meters)
  COMP
• GC0051 Z - 3,814,069.979 (meters)
  COMP
• GC0051 LAPLACE CORR- -0.87 (seconds)
  DEFLEC99
• GC0051 ELLIP HEIGHT- 132.18 (meters)
  (11/03/04) GPS OBS
• GC0051 GEOID HEIGHT- -30.33 (meters)
  GEOID03
• GC0051 DYNAMIC HT - 162.439 (meters)
  532.94 (feet) COMP

H

h

N
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Sample Datasheet

• GC0051.This mark is at Bowling Green-Warren Co
  Reg Airport (BWG)
• GC0051
• GC0051.The horizontal coordinates were
  established by GPS observations
• GC0051.and adjusted by the National Geodetic
  Survey in September 1994..
• GC0051
• GC0051.The orthometric height was determined by
  differential leveling
• GC0051 and adjusted by the National Geodetic
  Survey in June 1991..
• GC0051
• GC0051.The X, Y, and Z were computed from the
  position and the ellipsoidal ht.
• GC0051
• GC0051.The Laplace correction was computed from
  DEFLEC99 derived deflections.
• GC0051
• GC0051.The ellipsoidal height was determined by
  GPS observations
• GC0051 and is referenced to NAD 83.
• GC0051
• GC0051 The geoid height was determined by
  GEOID03.
• GC0051
• GC0051.The dynamic height is computed by
  dividing the NAVD 88
• GC0051.geopotential number by the normal gravity
  value computed on the

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Sample Datasheet

• GC0051 North East
  Units Scale Factor Converg.
• GC0051SPC KY1Z - 1,069,948.445
  1,439,883.460 MT 1.00003135 -0 24 52.0
• GC0051SPC KY1Z - 3,510,322.52 4,724,017.65
  sFT 1.00003135 -0 24 52.0
• GC0051SPC KY S - 569,937.685
  439,887.350 MT 0.99996641 -0 24 33.8
• GC0051SPC KY S - 1,869,870.55 1,443,197.08
  sFT 0.99996641 -0 24 33.8
• GC0051UTM 16 - 4,090,768.987
  551,185.068 MT 0.99963227 0 20 44.6
• GC0051
• GC0051! - Elev Factor x Scale
  Factor Combined Factor
• GC0051!SPC KY1Z - 0.99997926 x
  1.00003135 1.00001061
• GC0051!SPC KY S - 0.99997926 x
  0.99996641 0.99994567
• GC0051!UTM 16 - 0.99997926 x
  0.99963227 0.99961153
• GC0051
• GC0051 SUPERSEDED
  SURVEY CONTROL
• GC0051
• GC0051 ELLIP H (09/07/94) 132.24 (m)
  GP( ) 4 1
• GC0051 NAD 83(1986)- 36 57 41.83352(N) 086
  25 30.09113(W) AD( ) 3
• GC0051 NAD 27 - 36 57 41.69020(N) 086
  25 30.12570(W) AD( ) 3
• GC0051 NAVD 88 (01/09/97) 162.56 (m)
  533.3 (f) LEVELING 3
• GC0051 NGVD 29 (??/??/92) 162.696 (m)
  533.78 (f) ADJ UNCH 2 0

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Sample Datasheet

• GC0051 CBN - This is a Cooperative
  Base Network Control Station.
• GC0051 PACS - This is a Primary Airport
  Control Station.
• GC0051 DESIGNATION - BOWL PORT
• GC0051 PID - GC0051
• GC0051 STATE/COUNTY- KY/WARREN
• GC0051 USGS QUAD - BOWLING GREEN SOUTH
  (1993)
• GC0051
• GC0051 CURRENT SURVEY
  CONTROL
• GC0051 _________________________________________
  __________________________
• GC0051 NAD 83(1993)- 36 57 41.82528(N) 086
  25 30.08551(W) ADJUSTED
• GC0051 NAVD 88 - 162.565 (meters)
  533.35 (feet) ADJUSTED
• GC0051 _________________________________________
  __________________________
• GC0051 X - 318,174.533 (meters)
  COMP
• GC0051 Y - -5,092,731.546 (meters)
  COMP
• GC0051 Z - 3,814,069.979 (meters)
  COMP
• GC0051 LAPLACE CORR- -0.87 (seconds)
  DEFLEC99
• GC0051 ELLIP HEIGHT- 132.18 (meters)
  (11/03/04) GPS OBS
• GC0051 GEOID HEIGHT- -30.33 (meters)
  GEOID03
• GC0051 DYNAMIC HT - 162.439 (meters)
  532.94 (feet) COMP

H

h

N
NAVD88 Ellipsoid Ht Geoid Ht 162.565
132.18 32.16 -1.775 USGG2003 162.565
132.18 30.33 0.055 GEOID03
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The Missing Link

• Leveling-Derived Orthometric Heights
• Modeled Geoid Heights
• Whats left?

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Ellipsoid, Geoid, and Orthometric Heights
H Orthometric Height (NAVD 88)
h Ellipsoidal Height (NAD 83)
H h - N
N Geoid Height (GEOID 03)

TOPOGRAPHIC SURFACE
H
A
B
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enter GPS
(GNSS)
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Guidelines
Available On-Line at the NGS Web
Site www.ngs.noaa.gov/PUBS_LIB/pub_index.html
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Components of NGS-58

• Equipment requirements
• Field Procedures/Data Collection Parameters
• Basic Control Requirements
• Processing/Analysis Procedures

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Equipment Requirements

• Dual-frequency, full-wavelength GPS receiver
• Geodetic quality antennas with
  ground planes
• Fixed Height Poles

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Data Collection Parameters

• VDOP lt 6 for 90 or longer of 30 minute session
• Shorter session lengths stay lt 6 always
• Session lengths
• gt 30 minutes, collect 15 second data
• lt 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

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Two Days/Same Time
-10.254 -10.251
gt -10.253
Difference 0.3 cm
Truth -10.276
Difference 2.3 cm
Two Days/ Different Times
-10.254
gt -10.275
-10.295
Difference 4.1 cm
Truth -10.276
Difference 0.1 cm
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Four Basic Control Requirements

• Occupy stations with known NAVD 88 orthometric
  heights
• Stations should be evenly distributed throughout
  project
• Project areas lt 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 gt 20 km on a side, keep distances
  between GPS-occupied 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

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Processing Five Basic Procedures

• Perform 3-D minimally constrained (free)
  adjustment
• Analyze adjustment results
• Compute differences between GNSS-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

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GPS Ellipsoid Height Hierarchy
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High Accuracy Primary Control - CORS
KYMH Morehead State
LOU1 - Louisville
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High Accuracy Primary Control - HARN
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Have good NAVD88 Control
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Height Modernization Project
HARN - Average 50km, max 75km
Secondary - Average 12-15km, max 15km
Local Average 6-8 km, max 10km
Primary 20-25km, max 40km
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Sample Datasheet Leveling

• 1 National Geodetic Survey, Retrieval
  Date NOVEMBER 25, 2003
• AI6151
  
• AI6151 DESIGNATION - 2K76
• AI6151 PID - AI6151
• AI6151 STATE/COUNTY- WI/WASHINGTON
• AI6151 USGS QUAD - ALLENTON (1971)
• AI6151
• AI6151 CURRENT SURVEY
  CONTROL
• AI6151 _________________________________________
  __________________________
• AI6151 NAD 83(1997)- 43 25 39.39446(N) 088
  18 24.15369(W) ADJUSTED
• AI6151 NAVD 88 - 343.002 (meters)
  1125.33 (feet) ADJUSTED
• AI6151 _________________________________________
  __________________________
• AI6151 X - 137,097.884 (meters)
  COMP
• AI6151 Y - -4,637,622.691 (meters)
  COMP
• AI6151 Z - 4,362,336.158 (meters)
  COMP
• AI6151

AI6151 . . . AI6151 The orthometric height was
determined by differential leveling AI6151 and
adjusted by the National Geodetic Survey in
October 2000. AI6151
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Sample Datasheet - GNSS

• 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
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Sample Datasheet GNSS Using NGS58

• OM1256 CBN - This is a Cooperative
  Base Network Control Station.
• OM1256 DESIGNATION - CAMBRIA GPS
• OM1256 PID - OM1256
• OM1256 STATE/COUNTY- WI/COLUMBIA
• OM1256 USGS QUAD - RANDOLPH (1980)
• OM1256
• OM1256 CURRENT SURVEY
  CONTROL
• OM1256 _________________________________________
  __________________________
• OM1256 NAD 83(1997)- 43 34 10.47581(N) 089
  06 09.35995(W) ADJUSTED
• OM1256 NAVD 88 - 303.84 (meters)
  996.8 (feet) GPS OBS
• OM1256 _________________________________________
  __________________________
• OM1256 X - 72,495.418 (meters)
  COMP
• OM1256 Y - -4,628,194.515 (meters)
  COMP
• OM1256 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.
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Network / Local Accuracy
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Components of Implementation

• Densify CORS, HARNs
• Validate NAVD88 - leveling
• Remote Sensing improve DEMs
• Gravity improve Geoid
• Providing access to data
• Web sites
• Workshops
• Updated FIRMs
• Developing maintainance policies

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NGS Role and Responsibilities
O U T R E A C H E D U C A T I O N

• Program Management -- Congressional briefings,
  budget, grants management, coordination, develop
  plan to expand to a National Program
• Outreach/Technology Transfer -- advisors, forums,
  workshops, conferences, publications, training,
  capacity building
• Project Leadership -- project planning,
  specifications, guidelines, CORS management
• Quality Control -- training, assess techniques,
  survey control, load projects into NGS database
• Research and Development -- software development,
  remote sensing, modeling, investigate GPS
  techniques, antenna calibrations

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Results of Program Implementation
N E E D S B E N E F I T S

• Accurate, densified control network, consistent
  in 3 dimensions
• Rebuild decimated network
• New network is GPS-able
• Reduces survey costs by providing denser control
• Quality controlled by NGS

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Results of Program Implementation
N E E D S B E N E F I T S

• Access to NSRS for a variety of applications
• FEMAs Map Modernization put FIRMs on NAVD88
• Establishing RTK networks
• Data used by NGS to improve models and tools
  (DEMs, FIRMs, VDatum, HTDP, VTDP)
• Enables use of GPS as a cost effective
  positioning tool
• Build capacity in the surveying community to
  perform the surveys and properly use the data

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O U T R E A C H E D U C A T I O N
www.ngs.noaa.gov/heightmod
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Education - Seminars, Forums
Michigan, Washington
Leveling Spokane, 2006
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New and In Development
O U T R E A C H E D U C A T I O N

• Geoid models
• new model released about every 3 years
• Local models as needed
• OPUS Variety Pack
• OPUS-DB still in beta mode, but active effort to
  resolve problems
• OPUS-Projects in development, testing with
  Katrina project
• OPUS-RS is now available

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New and In Development
O U T R E A C H E D U C A T I O N

• Developing new guidelines
• RTK network surveying,
• leveling to CORS
• Other tools
• Pocket GPS Manager (PGM)
• vertical data collector
• VDatum
• improved software for processing leveling
• Online submission of data
• Training facility with field course and computer
  lab

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Partnerships
O U T R E A C H E D U C A T I O N

• Harris-Galveston Subsidence District
• State Agencies - North Carolina Geodetic Survey
• - South Carolina Geodetic Survey
• - Wisconsin Dept of Transportation
• - Alabama Dept of Revenue
• - Washington Dept of Natural Resources
• - Arizona State Land Dept
• Universities - TAMUCC, NCAT, LSU, USM, Scripps,
• Morehead State
• Other US Federal Agencies USACE, USGS, FEMA

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Spatial Reference Centers
65
Questions?
Contact information
Renee Shields Height Modernization
Manager N/NGS1, SSMC3, Room 9357 1315 East-West
Highway Silver Spring, MD 20910 301-713-3231,
x116 Renee.Shields_at_noaa.gov