National Geodetic Survey - Imagin · National Geodetic Survey’s Great Lakes Region Geodetic...
Transcript of National Geodetic Survey - Imagin · National Geodetic Survey’s Great Lakes Region Geodetic...
National Geodetic Survey
New Datums coming in 2022
IMAGIN Annual Conference
June 18, 2018
Who am I?
National Geodetic Survey’s
Great Lakes Region Geodetic Advisor
John Ellingson
Cell: 202-306-6904
Thank you for enabling me to come here
and spread the word about the coming new
datums.
Today’s Message…..
Two different datums are being modernized
1. “GEOPOTENTIAL” Datum (Vertical)
2. GEOMETRIC Datum (~Horizontal)
Let’s start with the
GEOPOTENTIAL DATUMreplacing the
North American Vertical Datum of 1988
(NAVD 88)
Goal: to enable use of new technology
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NAVD 88 suffers from bench marks that:
– Are often 80+ years old
– Are almost never re-checked for movement
– Disappear by the thousands every year
– Are seldom being replaced
– May not exist near locations where they are
needed
– Were all determined by leveling from a
single point, allowing unwanted cross-
country error build up
Replacing NAVD 88….Why isn’t NAVD 88
good enough anymore?
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Newer methods to determine/establish heights are
available (GNSS), but in many places NAVD 88 doesn’t
support them very well
Why isn’t NAVD 88 good
enough anymore?
There are areas where
NAVD 88 marks are
scarce….or do not exist
This example is 100 miles
across
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Initial point of NAVD 88 …. “FATHER POINT”
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Why replace NAVD 88?
• BIAS of Approximately ½ meter
• KNOWN TILT ..(about a meter) from SE to NW
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GRACE – (NASA and Germany)
“Gravity Recovery and Climate Experiment”
(launched 2002, decommissioned October 2017)
GOCE – (European Space Agency)
“Gravity Field and Steady-State Ocean Circulation
Explorer”
(launched 2009, ended November 2013)
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Gravity for the Redefinition of the American
Vertical Datum
• GRAV-D Goal: Create gravimetric geoid accurate to 1 cm where possible using airborne gravity data
• Overall Target: 2 cm accuracy orthometric heights from GNSS and a geoid model
• GRAV-D: Two thrusts of the project– Airborne gravity survey of entire
country and its holdings
– Long-term monitoring of geoid change
“TRANSITION TO THE FUTURE”
Official NGS policy as of Nov 14, 200710
Survey and Block Plans
• Data lines spaced 10 km
apart
• Cross lines spaced 60-
80 km apart
• Flight altitude 20,000 ft.
• Nominal speed 220-250
knots
GRAV-D current status
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GRAV-D status in Michigan
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NGS Gravity Slope Surveys
to verify that GRAV-D Works
GSVS 2011
GSVS 2014
GSVS 2017
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GRAV-D will produce the new 2022
GEOPOTENTIAL DATUM
known as “NAPGD2022”
……………
NGS will create a new GEOID Model in 2022
to match (use with) NAPGD2022
Older Geoid Models will NOT work with
NAPGD2022
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What changes can we expect to see
in our orthometric heights?
Some approx.
delta heights in
MICHIGAN (ft.)
These are
“leveled” height
differences
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-1.9’
-1.7’
-1.8’
-1.9’
-2.2’
-2.0’
-1.8’
-2.0’
-2.2’
-1.9’
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Let’s move on to the new
GEOMETRIC (3D) Datum…
*Latitude
*Longitude
*Ellipsoid Height
The North American Terrestrial
Reference Frame of 2022
“NATRF2022”
NAD 83 was aligned to “Geodetic Reference System
1980” (GRS80), and so was the original “World
Geodetic System 1984 (WGS84) meaning……
NAD 83 IS equivalent to the original WGS 84 …….but
NOT to the newer versions.
Newer versions of WGS 84 have been updated to be consistent with
updated International Terrestrial Reference Frames (ITRF**)
• G730 (June 1994) 0.7 m
• G873 (January 1997) 0.2 m
• G1150 (January 2002) 0.06 m
• G1674 (February 2012) 0.01 m
• G1762 (October 2013) 0.01 m
Why replace NAD 83?
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What is the difference between
ITRF 2008 and NAD 83?
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ITRF 08
Why a new
GEOMETRIC
DATUM?
The big picture
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How will these new datums impact my
work?
• Users in this region will see a GEOMETRIC (3-D) shift
of about 5.3’ (~4’ Lat/Lon & ~ 3.6’ El. HT)
• Some users may take years to switch to the new
datums…!
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The NGS 10 year plan states that a transformation tool will be
provided at the release of the new datums that will enable
users to transform values between the older datums (NAD 83
and NAVD 88) and the new GEOMETRIC and
GEOPOTENTIAL datums.
NGS will provide the tools that you
need to work with the new datums:
Wrap-up of
“New Datums”
• New GEOPOTENTIAL DATUM (vertical) named
“NAPGD2022”
(North American-Pacific Geopotential Datum of 2022)
• New GEOMETRIC DATUM (hz… really 3D)
named “NATRF2022”
(North American Terrestrial Reference Frame of 2022)
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Odds and Ends – (If time permits)
• NGS Industry Days took place in May 2018
• Update on State Plane Coordinate Systems for
New Datums
• IGLD..International Great Lakes Datum- Updated
in 2025
• OPUS-SHARE: Wait Times before you submit
your data to OPUS“Ultra-rapid” (iguWWWWD.sp3) 6-hour latency
“Rapid” (igrWWWWD.sp3) 13-hour latency
“Final or Precise” (igsWWWWD.sp3) 12 to 14 day latency
Questions….
My contact information:
John Ellingson
NGS Great Lakes Region Geodetic Advisor
Cell: 202-306-6904
Email: [email protected]
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