NSRS Modernization 2022New Datums

Scott Lokken

National Geodetic Survey, NOAAMid Atlantic Regional Geodetic Advisor

July 24, 2019

InfoAg Conference

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NGS Regional Advisors

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• Geodesist • 31 Years with NGS• GIS Certified• Farm Kid from SE N.D.

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.

NewReference SystemsPlanned for 2022

• Replace: bluebooking, database, State Plane Coordinates

• improve toolkit, surveying methodologies.

• Replace NAD83 with a geocentric reference frame

• GNSS based

• Replace NAVD88 with a gravity based geoid

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What matters to you?

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Low PrecisionLow Accuracy

HIgh PrecisionLow Accuracy

Low PrecisionHigh Accuracy

High PrecisionHigh Accuracy

Required Accuracy vs Precisiondetermines how the new datums will impact you.

Different times, different accuracy

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1981

2019

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

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Everything must shift

RED: NAD 83 coastline against NAD 83 imagery

GREEN: Coastline shifted into NATRF2022 but

the imagery remains on NAD 83

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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."

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Replacing NAD 83

The Old:

NAD 83(2011)

NAD 83(PA11)

NAD 83(MA11)

The New:

The North American Terrestrial Reference Frame of 2022

(NATRF2022)

The Caribbean Terrestrial Reference Frame of 2022

(CATRF2022)

The Pacific Terrestrial Reference Frame of 2022

(PATRF2022)

The Mariana Terrestrial Reference Frame of 2022

(MATRF2022)

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NAD 83 origin

ITRF epoch 2020.0 origin

Earth’s Surface

hNAD83 hNATRF2022fNAD83 – fNATRF2022

lNAD83 – lNATRF2022

hNAD83 – hNATRF2022

all vary smoothly by latitude and longitude

sameGRS-80ellipsoid

NAD 83’s non-geocentricity

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(NATRF 2022 origin)

GRS-80ellipsoid

Horizontal Shifts

• Approximate

IGS08(GRS80) minus NAD 83(2011)

~1 to 1.5 meters North America

~2.5 to 4 meters in Pacific

Ellipsoid Height Shifts

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Ellipsoid Height

Replacing NAVD88 (vertical)

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The Old:

NAVD88 The New:

The North American-Pacific Geopotential Datum of 2022

(NAPGD2022)

(Realized by a GNSS and a gravimetric geoid)

Replace NAVD 88

H

Earth’sSurface

The Geoid

H (NAVD 88)

Errors in NAVD 88: ~50 cm average, 100 cm CONUS tilt,

1-2 meters average in Alaska, NO tracking

(NAPGD2022)

NAPGD2022-NAVD88

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Approximate extent of

2022 geoid model used

for the “North American”

part of the new

geopotential reference

frame.

A few quick thoughts

(Note: Audience participation encouraged)

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1. Flat Earth???

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#2 Dynamic Earth??

tectonics

Earth Changes →

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#3 Sub Species → Equipment Operators???

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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.

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Examples of other Reference Frames

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• ITRF = International Terrestrial Reference Frame (ITRF)• IGS = GNSS portion of ITRF• Uses velocities

• WGS84 = World Geodetic System 1984

Note--these change with time

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

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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

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Why Modernize the Datums?

• Older Methodology

– Terrestrial, pre-space-geodesy, line-of-sight observations

– Easily destroyed, unmonitored passive control marks

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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

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• The current NSRS has issues:– Non-geocentricity of ellipsoid

– Outdated geoid as the zero height surface

– Does not account for time change

– Significant dependence upon passive marks

Drivers of change

Fixing these will cause a “shift”

Fixing this will cause a “drift”

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” coordinatesJuly 24, 2019 31

CORS Velocities – ITRF2014

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CORS Velocities – NATRF2022

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NGS Coodinate Conversion and Transformation ToolNCAT

• Replacing NADCON 4.2 and

GEOCON 2.0

• Support for nearly all

horizontal datums since 1897

– Exceptions: Regional Alaska

• No “state by state” grids

• Fixing all existing bugs

• Web service

• Consistent

• Documented

• Rigorous location-dependent

error estimates

• Ready to support 2022

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X, Y, Z

USNG UTM

SPC

f, l, h

X, Y, Z

USNG UTM

SPC

f, l, h

X, Y

, Z

USN

GU

TM

SPC

f, l

, hRegion: CONUS

NADCON 5 connections in RED

USSD

NAD 27

NAD 83 (1986)

NAD 83 (2011)

NAD 83 (NSRS2007)

NAD 83 (FBN)NAD 83 (HARN)

2022

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more info→www.geodesy.noaa.gov

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2019 Geospatial Summit

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Questions

Scott LokkenGeodesist, National Geodetic SurveyMid Atlantic Regional AdvisorSC, DE, MD, VA, NC, GA, USVI, PR

c/o USGS3916 Sunset Ridge RoadRaleigh, NC 27607

919-571-4047 office240-678-2167 mobileScott.Lokken@noaa.gov

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