National Height Modernization Program Renee Shields Christine Gallagher Great Lakes Region Height Modernization Consortium Fall Meeting 2012 Lansing, Michigan Wednesday, October 31, 2012

Overview NGS 10-year Plan Height Modernization Program Geoid Modeling at NGS

NGS Mission Statement To define, maintain and provide access to the National Spatial Reference System (NSRS) to meet our nation’s economic, social, and environmental needs. The NSRS is a consistent coordinate system that defines latitude, longitude, height, scale, gravity, and orientation throughout the United States.

Updating the NGS Ten Year Plan Why update? – Half way thru plan – Many goals accomplished, others outdated Major changes? – Reflects day to day work and modernization efforts – Grounded in traditional strategic planning Publication? – Public review completed in fall 2012 – Final publication in early 2013

NGS Ten Year Plan (2013 – 2023) GOAL 1: Support the Users of the National Spatial Reference System “Bluebooking and Datasheets” “Shoreline” “Airport Surveys” “Field Operations” “Online Tools” GOAL 2: Modernize and Improve the National Spatial Reference System “Replace NAD 83” “Replace NAVD 88” “Re-invent Bluebooking” “Fix the Toolkit” “Better Surveying” GOAL 3: Expand the NSRS stakeholder base through partnerships, education and outreach “Validate RTNs” “Engage New Stakeholders” “University Engagement” “Dynamic Web Presence” “Educational Portfolio” “IOCM” GOAL 4: Develop and enable a workforce with a supportive environment “Educated Workforce” “Recruiting” “Institutional Knowledge” ENTERPRISE GOAL: Improve Organizational and Administrative Functionality “Project Management” “I.T. Support” “Socio-Economic Awareness” “Records Management” “Regional Advisor Program”

Goal 1: Support Users of the NSRS Maintain ability to take in, validate, publish data −Bluebooking and datasheets Maintain production of National Shoreline −Shoreline mapping, emergency response Maintain airport surveying operational capacity −Aeronautical surveys - QA/QC for FAA Maintain geodetic surveying operational capacity −Perform operational geodetic surveys for research and testing, pilot projects, and training Maintain online tools −Provide tools to support users’ collection, processing, analysis of geodetic data

Goal 2: Modernize and Improve the NSRS Replace NAD 83 – Redefine datum; reduce definitional and access-related errors Replace NAVD 88 – Redefine datum; reduce definitional and access-related errors Re-invent “bluebooking” – Improve efficiency of data submission/delivery software Fix toolkit - Improve interoperability of NGS products with commercial software – Improve tools; increase accuracy of transformations and motion models; increase use of GIS Better surveying - Improve efficiency and accuracy of geospatial data collection methodologies – Update guidelines, such as NGS58/59, RTNs

Goal 3: Expand NSRS Stakeholder Base: Partnerships, Outreach, Education Process for RTN operators to align to NSRS – Ensure consistency between RTNs and NSRS, and each other; provide guidelines for use and management Engage new stakeholders – Participate in national and regional partner/stakeholder meetings and conferences; build user capacity to perform geodetic surveys, use tools Engage universities – Develop college-level seminars; collaborate in research activities Dynamic Web presence – Improve responsiveness to users through increased web access, communications Grow educational portfolio – Expand training capabilities at Corbin training center and online; develop comprehensive outreach plan Integrated Ocean & Coastal Mapping Program (IOCM) – Identify requirements, develop methodologies for topo and bathy lidar and imagery activities in support of Nautical Charting and Shoreline products

Goal 4: Enable Workforce Educate NGS Workforce – Formal and informal training opportunities, rotational assignments, increase involvement in professional orgs. Recruiting – Align Workforce with Mission – Increase number of field and office staff, recruit university graduates, interns, create open vacancy Institutional Knowledge – Define core capabilities, develop succession plan, mentoring program

Goal 5: Improve Organizational and Administrative Functionality Project Management I.T. Support Socio-economic Awareness Records Management Regional Advisor Program

 1994 – Meeting held in Sacramento, CA  1998 – Height Modernization Study funded  2000 – Height Modernization planning funded  2001 – Height Modernization funds directed to CA and NC; efforts began to study need in LA and WI  2002 to 2010 – Program expands to 18 funded states Height Modernization History

Height Modernization Activity

Height Modernization: future plans Updated NGS 10 year Plan Goal 1: Support NSRS users todayGoal 2: Modernize & improve NSRS Goals 3-5: Expand stakeholder base; improve workforce and organizational functionality Height Modernization National Plan Goal 1: Support NAVD 88 users today Goal 2: Modernize & improve vertical datum Goal 3: Increase technical capacity with stakeholder base & workforce

Height Modernization Program National Plan Maintain heights Accept data Publish datasheets Maintain online tools OPUS LOCUS Address gaps Improve models Update guidelines Complete pilot projects GOAL 1: Support NAVD 88 users today

Height Modernization Program National Plan Passive to active control Evaluate “infrastructure” Improve geoid GRAV-D Geoid Slope Validation Monitor motion Update guidelines Accepting and publishing data Improve data analysis (e.g. OPUS Projects) Modernize databases Develop new transformation tools GOAL 2: Modernize & improve vertical datum

Height Modernization Program National Plan Partner, educate, reach-out Continue Corbin classes Expand online training opportunities Maintain and expand partnerships State or federal agencies Universities Expert workforce Leverage new technology Continue supporting research Continue professional publications GOAL 3: Increase Technical Capacity

Height Modernization Program Recent Activities Projects Geoid Slope Validation Survey (‘11 & ‘13) Gulf Coast Height Modernization Project Updating HTDP Updating VTDP with Gulf Coast leveling Ecosystem and Climate (ECO) projects Products & Services GEOID 12A LOCUS Vdatum ArcGIS tool box Datasheet updates Geoid model information Publication in suspect areas Outreach & Coordination FGCS Vertical Reference System Working Group Height Mod Partner Meetings (‘12 & ‘13) Monthly teleconferences with guest presentations

Evolution of Height Modernization – Geoid Models and the Vertical Datum At the start of Height Mod NGS felt the Gravimetric geoid was adequate as the base for the Hybrid geoid, and that GPS on bench marks would enable continued use of NAVD What’s changed? Better accuracy from GNSS-derived heights – can use GNSS (CORS) to monitor changes in heights Better understanding of poor condition of vertical network – which continues to degrade Gravity holdings at NGS evaluated – impact on accuracy of USGG

Definitions: GEOIDS versus GEOID HEIGHTS “The equipotential surface of the Earth’s gravity field which best fits, in the least squares sense, (global) mean sea level.”* Can’t 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

In Search of the Geoid… Courtesy of Natural Resources Canada Dr. Dan Roman Dr. Xiaopeng Li Drs. Yan Wang and Simon Holmes not pictured

Orthometric heights – Measure by leveling surveys – Most accurate but most expensive – Difficult to maintain over time, esp. on national scale Ellipsoid heights – Inherent to GNSS measurements – Need accurate ellipsoid height control – Better field procedures = better heights Geoid heights – Derived from model developed from gravity observations – Can provide relationship between e.h. and o.h. Measuring and relating different kinds of heights

(NAVD 88) H H = Orthometric Height (leveling) H = h - N TOPOGRAPHIC SURFACE h = Ellipsoidal Height (GPS) N = Geoid Height (model) h (NAD 83) Ellipsoid N Geoid Geoid Height (GEOIDxx) Ellipsoid, Geoid, and Orthometric Heights With 2 known heights we can calculate the 3rd

NGS’ Two Geoid Models Gravitational model: includes terrestrial and satellite gravity data, EGM08, and the Residual Terrain Model is a purely gravitational model and hence good for scientific applications does not provide relationship between GPS heights and NAVD 88 “Hybrid” model: starts with gravitational model adds well-distributed accurate GPS on bench marks to enable a fit to NAVD 88

Hybrid Geoid Height Models (e.g., GEOID12A), Gravimetric Geoid Height Models (e.g., USGG2012) and Conversion Surfaces using GPS on BM data Gravimetric Geoid systematic misfit to BM’s but best fits “true” heights Hybrid Geoid “converted” to fit local BM’s, so best fits NAVD 88 heights Conversion Surface model of systematic misfit derived from BM’s in IDB Earth’s Surface h h h h h H H H H H N N N N N Ellipsoid Hybrid Geoid Geoid Gravimetric Geoid

Control Data for GEOID12 Modeling RegionReference Frame Vertical Datum# GPSBM used (# Rejected) #OPUSDB used (# Rejected) CONUSNAD 83 (2011)NAVD 88* 24,003 (868)478 (258) - VTDP RegionNAD 83 (2011)NAVD 88/VTDP 357 (153)1 (17) AlaskaNAD 83 (2011)NAVD 88** 105 (4)2 (1) Puerto RicoNAD 83 (2011)PRVD U.S. Virgin IslandsNAD 83 (2011)VIVD 0921 (3)0 HawaiiNAD 83 (PA11)Geoid (W 0 )n/a American SamoaNAD 83 (PA11)ASVD 0219 (3)0 GuamNAD 83 (MA11)GUVD CNMINAD 83 (MA11)NMVD * Supplemented by 574 (5 rejected) in Canada and 674 (70 rejected) in Mexico ** Supplemented by 88 (2 rejected) in Canada

Ellipsoid Height Changes (NA2011-NA2007)

Orthometric Height Changes (mm)

Distribution of OPUSDBBM12

The Impact of OPUS

GEOID12 Error Map for Southwest Triangles show locations of GPSBM2012 & OPUSDBBM12 control points. Error increases based on the size of the gap. Dense coverage yields < 1 cm. Errors will be provided with GEOID12A hts.

GPSBM1999: 6,169 total 0 Canada STDEV 9.2 cm (2σ) GPSBM2003: 14,185 total 579 Canada STDEV 4.8 cm (2σ) GPSBM2009: 18,291 total 576 Canada STDEV 2.8 cm (2σ) For 2009 and 12A Rejections based on: S: State adviser h: ell ht err (NRA) H: ortho ht err N: geoid err (misfit) D: duplicate

An additional 6,000 points?

GEOID12 – GEOID09

Release of GEOID12A

GEOID12A - GEOID12

GEOID12A Complete for all regions Converts between NAD 83 (**11) and local vertical datum (NAVD 88 in CONUS) Modeling is much the same; new data had an impact: – Additional data in Mexico – OPUSDBBM12 (i.e. GPS on Bench Marks from OPUS DB) VISIT:

GEOID12A is built on USGG2012 – so how good is USGG? Most of the historical NGS data is terrestrial Multiple observers, multiple processors over the past 60 years Numerous corrections and datums over time Metadata maintained in paper records Very limited aerogravity Deficit in near-shore gravity data

Replace the Vertical Datum of the USA by 2022 (at today’s funding) with a gravimetric geoid accurate to 1 cm Orthometric heights accessed via GNSS Three thrusts of project: –Airborne gravity survey of entire country and its holdings –Long-term monitoring of geoid change –Partnership surveys Working to launch a collaborative effort with the USGS for simultaneous magnetic measurement Gravity for the Redefinition of the American Vertical Datum (GRAV-D) June 21, Height Mod Partners Meeting

Building a Gravity Field Long Wavelengths: (≥ 350 km) GRACE and GOCE (not shown) Intermediate Wavelengths (500 km to 20 km) Airborne Measurement Surface Measurement Short Wavelengths (< 100 km) + +

Continental US White = FY13 Orange = FY12 Green = FY11 and earlier Complete In FY13

Alaska White = FY13 Orange = FY12 Green = FY11 and earlier

Geoid Slope Validation Survey Proof of concept: Does the addition of the airborne data make for a geoid accurate at 1 cm??? June 21, 2012Height Mod Partners Meeting43

2011GSVS June 21, 2012Height Mod Partners Meeting 325 km 218 points 1.5 km apart Austin Rockport GPS: 20 identical. units, 10/day leapfrog, 40 hrs ea. Leveling: 1 st order, class II, digital barcode leveling Gravity: FG-5 and A-10 anchors, 4 L/R in 2 teams DoV: ETH Zurich DIADEM GPS & camera system LIDAR : Riegl Q680i-D, 2 pt/m 2 spacing, 0.5 km width Imagery: Applanix 439 RGB DualCam, 5000’ AGL Other: RTN, short-session GPS, extra gravity marks around Austin, gravity gradients 44

2011 GSVS June 21, 2012Height Mod Partners Meeting 325 km 218 points 1.5 km apart Austin Rockport Observe geoid shape (slope) using multiple independent terrestrial survey methods – GPS + Leveling – Deflections of the Vertical Compare observed slopes (from terrestrial surveys) to modeled slopes (from gravimetry or satellites) – With / Without new GRAV-D airborne gravity 45

Geoid Slope Survey Conclusions Including airborne gravity data improves geoid slope accuracy at nearly all distances <325 km The NGS geoid in the TX survey meets the 1 cm accuracy objective only if airborne data are included – No other model achieved 1 cm accuracy Gravimetric geoid models and GPS are a viable alternative to long-line leveling June 21, 2012Height Mod Partners Meeting46

Geoid Models Page: – GRAV-D Page: – Geoid Team: – Dan Roman (x161), Yan Wang (x127), Xiaopeng Li (x210) GRAV-D Project Manager: – Vicki Childers x161

QUESTIONS? , x x105