Modernization of the National Spatial Reference System Keeping Pace with Changes in Positioning Technology and User Expectations in a Dynamic World

Transcription

1 Modernization of the National Spatial Reference System Keeping Pace with Changes in Positioning Technology and User Expectations in a Dynamic World Wisconsin Society of Land Surveyors Institute Wisconsin Dells January 24, 2018 Dave Doyle NGS, Chief Geodetic Surveyor (Retired) base9geodesy@gmail.com

2 Can You Answer These Questions? 1) What, if any, are the most significant problems with both NAD 83 and NAVD 88? 2) What is the approximate positional difference between NAD 83 and the ITRF? 3) What organization is responsible for this standard? 4) What 4 geodetic measurement techniques are used to define the standard? 5) What is the biggest problem that keeps leveled height differences from being the same as those derived strictly by gravity observations? 6) Why do surveyors need to understand the epoch of coordinates and heights? 7) How fast and in what direction is Milwaukee moving as part of the North American tectonic plate per year? 8) What is the most current iteration of the World Geodetic System of 1984 (WGS 84) called? 9) How does IGS08 relate to ITRF08?

3 The National Geodetic Survey 10 year plan Mission, Vision and Strategy Official NGS policy as of Jan 31, 2013 Updates 2008 plan Modernized and Improve NSRS Attention to accuracy Attention to time-changes Improved products and services Fully vetted by NSPS/AAGS 2022 Targets: Replace NAD 83 and NAVD 88 Cm-accuracy access to all coordinates

4 Problems with NAD 83 and NAVD 88 NAD 83 is not as geocentric as it could be (approx. 1.5 m for CONUS). Surveyors don t see this Yet NAD 83 is not well defined with positional velocities NAVD 88 is realized by passive control (bench marks) most of which have not been releveled in years NAVD 88 does not easily account for local vertical velocities (subsidence/uplift) Post glacial isostatic readjustment (Forebulge collapse) Subsurface fluid/hydrocarbon extraction Sediment loading - Compaction Sea level rise

5 New Reference Frame Names NAD 83 becomes: North American Terrestrial Reference Frame (NATR2022) Caribbean Terrestrial Reference Frame (CTRF2022) Mariana Terrestrial Reference Frame (MTRF2022) Pacific Terrestrial Reference Frame (PTRF2022) NAVD 88 becomes: North American-Pacific Geopotential Datum of 2022 (NAPGD2022) Realized by GEOID2022

6 Cutting Edge Surveying Technology circa 1890

7 Salina, KS Baseline Measurement km/4.1 mi required about 5 weeks Precision ~ 8 mm/0.03 ft (1:721,600)

8 Advances in distance measurement technology Early 1900s

9 Electronic technology 1950s

10 A Game Changer

11 Global Navigation Satellite Systems US - GPS Russia - GLONASS EU - Galileo China BeiDou Four positioning and navigation systems NAVSTAR/GPS US (Currently 31) GLONASS Russia (Currently 24) Galileo EU (Currently 22, 4 planned for 2018) BeiDou3 China (Currently 2, 30 by 2020?)

12 Global Navigation Satellite Systems US - GPS Russia - GLONASS EU - Galileo China BeiDou 22

13 International Gold Standard International Earth Rotation and Reference System Service (IERS) Established 1987 Office in Paris, France Produces the International Terrestrial Reference System And International Terrestrial Reference Frame First ITRF 1988 Current ITRF 2014

14 IERS Four Geodetic Services International GNSS Service International DORIS Service International Laser Ranging Service International VLBI Service

15 Tectonic Plate Velocities

16 Tectonic Plate Velocities Horizontal Vertical IGS08 Velocities Mequon WIM5 N = m/yr E = m/yr U = m/yr

17 IGS08 is the GNSS component of the ITRF08 They can be considered to be equivalent MEQUON 5 (WIM5), WISCONSIN Antenna Reference Point(ARP): MEQUON 5 CORS ARP PID = DI2110 IGS08 POSITION (EPOCH ) Computed in Aug 2011 using data through gpswk X = m latitude = N Y = m longitude = W Z = m ellipsoid height = m IGS08 VELOCITY Computed in Aug 2011 using data through gpswk VX = m/yr northward = m/yr VY = m/yr eastward = m/yr VZ = m/yr upward = m/yr DEHt NAD_83 (2011) POSITION (EPOCH ) Transformed from IGS08 (epoch ) position in Aug X = m latitude = N Y = m longitude = W Z = m ellipsoid height = m NAD_83 (2011) VELOCITY Transformed from IGS08 velocity in Aug VX = m/yr northward = m/yr VY = m/yr eastward = m/yr VZ = m/yr upward = m/yr IGS08 NAD 83(2011) DHoriz = 1.095m/3.59ft = 1.042m/3.42ft

18 Simplified Concept of NAD 83 vs. ITRF/IGS h NAD83 h ITRF/IGS Earth s Surface ~ 1.5 m +/- 0.2 m CONUS ~ 1.4 m +/- 0.1 m AK ~ 1.9 m PR & VI ~ 2.5 m HI ~ 3.1 m AS ~ 2.3 m +/- 0.1 m GU & NM Mequon WIM5 dx = m dy = m dz = m 3D = m ITRF/IGS Origin NAD 83 Origin Identically shaped ellipsoids (GRS-80) a = 6,378, meters (semi-major axis) 1/f = (flattening)

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21 Why isn t NAVD 88 good enough anymore? Approximate level of global geoid mismatch known to exist in the NAVD 88 zero surface:

22 Passive Vertical Control Mark Problems -- Are rarely re-leveled for movement -- Disappear by the hundreds every year -- Are not funded for replacement -- Are not often readily located for GPS observations -- Don t exist in most of Alaska -- Determined by leveling from a single point allowing cross-country error build up.

23 GEOID 12A/B ACCURACY

24 GEOID 12A/B Accuracy in Wisconsin

25 Post GEOID12B GPS on BM data in Wisconsin

26 NGS Plan for GEOID 19? Early January Produce a beta model with new data select Web Map End of February 2018 Engage surveyors to fill in GPS on BM gaps w/opus Share Solutions and/or OPUS Projects (Work w/regional Advisor John Ellingson) End of August 2018 Cut off acceptance of new GPS on BM data December 2018 Release BETA model Early 2019 Collect user feedback and resolve problems April 2019 Release final geoid model

27 NGS CORS Networked Data Some, but not all, CORS currently collect GLONASS data Can be provided to user by request NGS processing software PAGES/OPUS uses only GPS data NGS is currently reprocessing all CORS project REPRO new NAD 83 (2011) and IGS14 coordinates and updated velocities excepted soon (Spring 18?) NGS not likely to adjust existing passive GPS stations with respect to any CORS changes from REPRO New all viable GNSS processing software to replace PAGES being developed target 2022?

28 OPUS DB Simple Shared Data NGS Archived Update scaled NAD 83 positions for most NAVD 88 BMs Position NAVD 88 BMs for inclusion in next geoid model Helps improve accuracy of future vertical datum transformation tool Validate position/height of stations published in NSRS Position your new marks Position marks of other agencies not already in NSRS: USGS USACE BOR GLO/BLM State DoT

29 What can you do to improve the next NGS geoid model? / 2022 vertical transformation tool? OPUS DB Shared Solutions

30 Transition to the Future GRAV-D Gravity for the Redefinition of the American Vertical Datum Official NGS policy as of Nov 14, 2007 $38.5M over 10 years Airborne Gravity Snapshot Absolute Gravity Tracking Re-define the Vertical Datum of the USA by 2022 Approximately 64% Complete

31 Space-Base Gravity Observations Gravity Recovery And Climate Experiment (GRACE) 137 mi apart/310 miles high Launched March 2002 Mission End October 2017 Gravity field and steady state Ocean Circulation Explorer (GOCE) Launched March 2009 Re-entry November 2013

32 Building a Gravity Field Long Wavelengths ( 250 km) GRACE/GOCE/Satellite Altimetry + Intermediate Wavelengths (500 km to 20 km) Airborne Measurement Surface Measurement and Predicted Gravity from Topography + Short Wavelengths (< 100 km)

33 GRAV-D STATUS : ~ 64% 33

34 SURVEY AND BLOCK PLANS Layout rectangular survey 400 x 500 km Extends beyond the shelf break Block size will reflect the endurance of the aircraft 34

35 SURVEY AND BLOCK PLANS Data lines spaced 10 km apart Cross lines spaced km apart Flight altitude 20,000 ft Nominal speed kts 35

36 GRAV-D AIRCRAFT DOI Bureau of Land Management Pilatus PC-12 Fugro King Air E-90A Cessna Conquest Naval Research Lab King Air RC-12 NOAA Gulfstream Jet Prop NOAA P-3 Hurricane Hunter Pilatus PC-12 King Air RC-12 King Air E-90A 36

37 GRAV-D Reconnaissance Survey GPS Base Stations Parking Space Gravity Tie 37

38 Gravity and GPS Base Stations Parking spot ID Micro-G A10 Absolute Gravity measurement GPS Base Stations Vertical gravity gradient 38

39 GRAV-D Aircraft Instrumentation Micro-g LaCoste TAGS Gravimeter NovAtel SPAN-SE w/ Honeywell µirs IMU Both instruments include GNSS receivers SPAN system allows for tightly coupled GPS/IMU solutions 39

40 INSTRUMENT INSTALLATION Instrument suite installed Lever arm survey required Test flight performed 40

41 BETA GEOID MODEL COMPUTATION The gravity data from satellites, airborne, corrected surface data, and terrain predictions will be blended into a gravity field As regions are completed, beta preliminary geoid models will be created and released to the public for local testing Create a gravimetric geoid model that will be the basis of the new vertical datum 41

42 Why GRAV-D? A relatively small workforce can update the geoid as compared to the large workforce needed to re-level bench marks As the H=0 surface (W 0 ), the geoid will be tracked over time to keep the datum up to date. Also known as the equipotential surface W 0 = 62,636,856.0 m 2 /s 2 A 2 cm target accuracy anywhere that GNSS receivers can be used, kept up to date through monitoring CORS and the geoid, is better than the accuracy and accessibility of NAVD 88 today It is far cheaper than leveling The geoid can t be bulldozed out of usefulness The effect of subsidence/uplift upon the realization will be known (and accounted for) by monitoring CORS and monitoring the geoid

43 What is GRAV-D? GRAV-D will mean: As the H=0 surface, the geoid will be tracked over time to keep the datum up to date The reliance on passive marks will dwindle to: Secondary access to the datum Minimal NGS involvement Maintenance/checking in the hands of users Use at your own risk

44 How will I access the new vertical datum? Primary access (NGS mission) Users with geodetic quality GNSS receivers will continue to use OPUS suite of tools and other standard processing methods (e.g. RTNs, RTK, Static ) Ellipsoid heights computed, and then a gravimetric geoid applied to provide orthometric heights in the new datum No passive marks needed But, could be used to position a passive mark

45 How will I access the new vertical datum? Secondary access (Use at your own risk) Passive marks that have been tied to the new vertical datum NGS will provide a data sharing service (e.g. OPUS Shared Solutions) for these points, but their accuracy (due to either the quality of the survey or the age of the data) will not be a responsibility of NGS

46 How will I access the new vertical datum? NAVD 88 conversion to new datum A conversion will be provided between NAVD 88 and the new datum Only where recent GNSS ellipsoid heights exist to provide modern heights in the new reference system

47 Geopotential Datum Changes USGG2012

48 BETA Geoid Model Computation The gravity data from satellites, airborne, corrected surface data, and terrain predictions will be blended into a gravity field As regions are completed, beta preliminary geoid models will be created and released to the public for local testing Create a gravimetric geoid model that will be the basis of the new vertical datum 48

49 xgeoid17 Experimental Model First experimental geoid published in June 2014 Includes all GRAV-D processed by the end of the previous year xgeoid17a Covers entire U.S. but does not include any GRAV-D data xgeoid17b Covers those areas of U.S. that include processed GRAV-D data (CONUS, ALASKA, PR & VI)

50 Predicted Position & Height Changes in 2022 WISCONSIN Near Milwaukee Computed for MILWAUKEE B (AA8062) HORIZONTAL = 1.27 m (4.2 ft) ELLIPSOID HEIGHT = m (- 3.5 ft) ORTHOMETRIC HEIGHT = m (- 2.2 ft) Computed with xgeoid17b Eau Claire Computed for CEC 5 (DJ4662) HORIZONTAL = 1.32 m (4.3 ft) ELLIPSOID HEIGHT = m (- 3.1 ft) ORTHOMETRIC HEIGHT = m (- 2.5 ft) Computed with xgeoid17b

51 Predicted Position & Height Changes in 2022 WISCONSIN Near Green Bay Computed for H (AH5305) HORIZONTAL = 1.30 m (4.3 ft) ELLIPSOID HEIGHT = m (- 3.3 ft) ORTHOMETRIC HEIGHT = m (- 2.2 ft) Computed with xgeoid17b Eagle River Computed for EAGLE RIVER GPS (QM0771) HORIZONTAL = 1.32 m (4.3 ft) ELLIPSOID HEIGHT = m (- 3.1 ft) ORTHOMETRIC HEIGHT = m (- 2.3 ft) Computed with xgeoid17b

52 Predicted Position & Height Changes in 2022 WISCONSIN Near Superior Computed for 315 RESET (RN1693) HORIZONTAL = 1.35 m (4.4 ft) ELLIPSOID HEIGHT = m (- 2.9 ft) ORTHOMETRIC HEIGHT = m (- 2.5 ft) Computed with xgeoid17b Stevens Point Computed for 5U04 (DJ4385) HORIZONTAL = 1.31 m (4.3 ft) ELLIPSOID HEIGHT = m (- 3.3 ft) ORTHOMETRIC HEIGHT = m (- 2.4 ft) Computed with xgeoid17b

53 Predicted 2022 Orthometric Heights From OPUS Make geoid-based orthometric heights available via OPUS - Done, in extended output

54 Metadata Coordinates and heights without appropriate metadata have the same value as a boundary line in Google Earth Just A Wild A** Guess

55 METADATA DATA ABOUT DATA Datums and Realizations NAD 27, NAD 83(1986), NAD83 (199X), NAD 83 (2007), NAD 83 (2011), Epoch xxxx.xx NGVD29, NAVD88 Units of Measure Meters, U.S. Survey Feet, International Feet Accuracy Horizontal & Vertical 0.03 m, 0.1 ft, 1 st -, 2 nd -, 3 rd - Order etc. How accurate are values really?

56 Examples of Bad Metadata LE0000 STATION RECOVERY (2013) LE0000 LE0000'RECOVERY NOTE BY INDIVIDUAL CONTRIBUTORS 2013 LE0000'RECOVERED BY XXXX ENGINEERING COMPANY LE0000'RECOVERED WITH THE FOLLOWING READINGS LE0000'LAT N03x 50' LE0000'LONG W09x 20' LE0000'ELEV LE0000' LE0000'NAD83 IOWA STATE PLANES, SOUTH ZONE, US FOOT LE0000'NORTHING x ' LE0000'EASTING xx '

57 What can you do to get ready for 2022?? Understand the impact of changing positions and heights for your community, company or agency Watch for upcoming NGS status reports/webinars Consider legislative changes to Wisconsin Statutes, Chapter 236, Subchapter NGS plans to publish State Plane Coordinates using the same geometric parameters as NAD 83 NGS SPC contact Michael Dennis Communicate your issues directly to NGS John Ellingson Great Lakes Regional Advisor Dru.Smith NSRS Modernization Manager

58 GOOD COORDINATION BEGINS WITH GOOD COORDINATES GEOGRAPHY WITHOUT GEODESY IS A FELONY