InfoAg Conference NSRS Modernization 2022 New Datums Scott Lokken National Geodetic Survey, NOAA Mid Atlantic Regional Geodetic Advisor July 24, 2019
July 24, 2019 1 NGS Regional Advisors
• Geodesist • 31 Years with NGS • GIS Certified • Farm Kid from SE N.D.
July 24, 2019 2 National Spatial Reference System (NSRS) NGS Mission: To define, maintain & provide access to the National Spatial Reference System (NSRS) to meet our Nation’s economic, social & environmental needs
Consistent National Coordinate System • Latitude/Northing • Longitude/Easting • Height • Scale • Gravity • Orientation and how these values change with time. New Reference Systems Planned for 2022 • Replace NAD83 with a geocentric reference frame • GNSS based • Replace NAVD88 with a gravity based geoid
• Replace: bluebooking, database, State Plane Coordinates July 24, 2019 • improve toolkit, surveying methodologies. 4 What matters to you? Required Accuracy vs Precision determines how the new datums will impact you.
Low Precision HIgh Precision Low Precision High Precision Low Accuracy Low Accuracy High Accuracy High Accuracy
July 24, 2019 5 Different times, different accuracy
2019
1981
July 24, 2019 6 Bottom Line, Up Front
• If you do geospatial work in the USA… • and you work in the National Spatial Reference System.. • every product you’ve ever made… – every survey… – every map… – every lidar point cloud… – every image… – every DEM… – WILL have the wrong coordinates on it in 3 years.
Let’s talk about what this means, why it is happening, and how it will affect things going forward
July 24, 2019 7 Everything must shift
RED: NAD 83 coastline against NAD 83 imagery GREEN: Coastline shifted into NATRF2022 but the imagery remains on NAD 83
July 24, 2019 8 What is a Datum?
• "A set of constants specifying the coordinate system used for geodetic control, i.e., for calculating the coordinates of points on the Earth."
• "The datum, as defined 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."
July 24, 2019 9 Replacing NAD 83
The Old: The New: NAD 83(2011) The North American Terrestrial Reference Frame of 2022 (NATRF2022) NAD 83(PA11) The Caribbean Terrestrial Reference Frame of 2022 NAD 83(MA11) (CATRF2022)
The Pacific Terrestrial Reference Frame of 2022 (PATRF2022)
The Mariana Terrestrial Reference Frame of 2022 (MATRF2022)
July 24, 2019 10 NAD 83’s non-geocentricity GRS-80 ellipsoid Earth’s Surface h NAD83 fNAD83 – fNATRF2022 hNATRF2022 lNAD83 – lNATRF2022 hNAD83 – hNATRF2022 all vary smoothly by latitude and longitude
ITRF epoch 2020.0 origin same GRS-80 (NATRF 2022 origin) ellipsoid
NAD 83 origin
July 24, 2019 11 Horizontal Shifts ~1 to 1.5 meters North America ~2.5 to 4 meters in Pacific
• Approximate IGS08(GRS80) minus NAD 83(2011) Ellipsoid Height Shifts
Ellipsoid Height
July 24, 2019 13 Replacing NAVD88 (vertical)
The Old: NAVD88 The New: The North American-Pacific Geopotential Datum of 2022 (NAPGD2022)
(Realized by a GNSS and a gravimetric geoid)
July 24, 2019 14 Replace NAVD 88
Earth’s Surface H (NAVD 88) H
The Geoid (NAPGD2022)
Errors in NAVD 88: ~50 cm average, 100 cm CONUS tilt, 1-2 meters average in Alaska, NO tracking NAPGD2022-NAVD88
July 24, 2019 16 Approximate extent of 2022 geoid model used for the “North American” part of the new geopotential reference frame.
July 24, 2019 17 A few quick thoughts
(Note: Audience participation encouraged)
July 24, 2019 18 1. Flat Earth???
July 24, 2019 19 #2 Dynamic Earth??
tectonics
Earth Changes →
July 24, 2019 20 #3 Sub Species → Equipment Operators???
July 24, 2019 21 Overview Current Datums
• The National Spatial Reference System (NSRS) is the official coordinate system for all geospatial work done by the civilian federal government.
• Current datums: – NAD 83 (latitude, longitude, ellipsoid height) – NAVD 88 (orthometric height) – IGLD 85 (dynamic heights: predominantly on the Great Lakes)
• These datums are often adopted, even legislated, by states, counties and municipalities.
July 24, 2019 22 Examples of other Reference Frames
• ITRF = International Terrestrial Reference Frame (ITRF) • IGS = GNSS portion of ITRF • Uses velocities • WGS84 = World Geodetic System 1984
Note--these change with time
July 24, 2019 23 Mixing NSRS and non-NSRS?
• Just do it right • Right: – The Oregon CRS has a mathematically defined relationship to the NSRS • Wrong: – “WGS 84 is the same as NAD 83” – “WGS 84 is the same as the ITRF” – “Sub-meter accuracy is possible using WGS 84” • Such statements gloss over critical facts about history, accuracy and application
July 24, 2019 24 Accuracy
• Consider your users’ accuracy needs – 3 Meters? • Then WGS 84 is NAD 83 • Global 14 parameter transformations will suffice – 3 Decimeters? • Then NAD 83(2011) is NAD 83(NSRS2007) – But NAD 83(1986) is not the same as NAD 83(HARN) • NADCON will suffice as a transformation – 3 Centimeters? • Every detail matters
July 24, 2019 25 Why Modernize the Datums?
• Older Methodology – Terrestrial, pre-space-geodesy, line-of-sight observations – Easily destroyed, unmonitored passive control marks
July 24, 2019 26 Why Modernize?
• Evidence of systematic errors – Decades of space geodetic observations • All of the datums contain systematic errors (decimeters to meters) – At scales larger than today’s accuracy capabilities (centimeters)
– Origin (center of Earth) offset: 2+ meters – Zero elevation surface: 0.5 to 2+ meters
July 24, 2019 27 Drivers of change
• The current NSRS has issues: – Non-geocentricity of ellipsoid Fixing these will cause a “shift” – Outdated geoid as the zero height surface – Does not account for time change Fixing this will cause a “drift” – Significant dependence upon passive marks Drift • The second major change you’ll see in 2022 is a drift in coordinates – Everything in the world moves – Coordinates will be associated with the actual date when the data was taken! – Velocities at all marks can be estimated • Euler Pole Rotation • new tool, called the Intra-Frame Velocity Model (IFVM2022) – Two things will mitigate the pain of time-dependent coordinates: • “Plate Fixed” frames • “Reference Epoch” coordinates July 24, 2019 31 CORS Velocities – ITRF2014
July 24, 2019 32 CORS Velocities – NATRF2022
July 24, 2019 33 NGS Coodinate Conversion and Transformation Tool NCAT
• Replacing NADCON 4.2 and • Web service GEOCON 2.0 • Consistent • Support for nearly all • Documented horizontal datums since 1897 • Rigorous location-dependent – Exceptions: Regional Alaska error estimates • No “state by state” grids • Ready to support 2022 • Fixing all existing bugs
July 24, 2019 34
SPC
UTM
, h , l
Region: CONUS 2022 , USSD f
NADCON 5 connections in RED USNG X, Y, Y, X, Z
NAD 27 NAD 83 (2011)
NAD 83 (NSRS2007) NAD 83 (1986) NAD 83 (FBN) NAD 83 (HARN) f, l, h f, l, h
X, Y, Z SPC X, Y, Z SPC
USNG UTM USNG UTM July 24, 2019 35 more info→ www.geodesy.noaa.gov
July 24, 2019 36 July 24, 2019 37 2019 Geospatial Summit
July 24, 2019 38 July 24, 2019
39 Questions
Scott Lokken Geodesist, National Geodetic Survey Mid Atlantic Regional Advisor SC, DE, MD, VA, NC, GA, USVI, PR
c/o USGS 3916 Sunset Ridge Road Raleigh, NC 27607
919-571-4047 office 240-678-2167 mobile [email protected]
July 24, 2019 40