GEOID12/GEOID12A

For 9/13/2012 HT MOD meeting

Dan RomanGeosciences Research Division

OUTLINE• GEOID12 – from the ESRI Survey Summit• Erroneous data• GEPOID12A Development and Release

GEOID12 Technical Details

Daniel Roman1, Xiaopeng Li2, and Simon Holmes3

1 Geosciences Research Division, NGS, NOAA, Silver Spring MD

2 Earth Resources Technology (ERT), Inc., Silver Spring MD

3 Stinger Ghaffarian Technology (SGT) Inc., Greenbelt MD

The Survey Summit

Sunday, 22 July 2012 (Manchester Grand Hyatt), Geodesy Session, 1030-1200

Basic Concepts on Modeling• Start with a gravimetric geoid (USGG2012)• Use control data to fit to local datums– Appropriate versions of NAD 83– Respective local Vertical Datum (if one exists)

• Use LSC to determine correlated signal• For complex areas (e.g., CONUS), use MMLSC• Apply grid of correlated signal to USGG2012• Results in GEOID12 with high frequency

nature from USGG2012 but fit to local control

Hybrid Geoid Height Models (e.g., GEOID12), 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

hh

h hh

HH

HH

H

NNNNN

Ellipsoid

Hybrid Geoid

Gravimetric Geoid Geoid-0.737 M in Salt Lake – 2009 model

USGG2012 – USGG2009

Control Data for GEOID12 Modeling

Region Reference Frame

Vertical Datum

# GPSBM used (# Rejected)

#OPUSDB used(# Rejected)

CONUS NAD 83 (2011) NAVD 88 * 24,003 (868) 478 (258)

- VTDP Region NAD 83 (2011) NAVD 88/VTDP 357 (153) 1 (17)

Alaska NAD 83 (2011) NAVD 88 ** 105 (4) 2 (1)

Puerto Rico NAD 83 (2011) PRVD 02 38 0

U.S. Virgin Islands NAD 83 (2011) VIVD 09 21 (3) 0

Hawaii NAD 83 (PA11) Geoid (W0) n/a n/a

American Samoa NAD 83 (PA11) ASVD 02 19 (3) 0

Guam NAD 83 (MA11) GUVD 04 33 0

CNMI NAD 83 (MA11) NMVD 03 55 0* Supplemented by 574 (5 rejected) in Canada and 674 (70 rejected) in Mexico** Supplemented by 88 (2 rejected) in Canadahttp://www.ngs.noaa.gov/GEOID/GEOID12/GPSonBM12.shtml

Ellipsoid Height Changes (National Adjustment of 2011-National Adjustment of 2007)

Rejections based on adjustment error (National Adjustment of 2011 => ‘h’ Reject code)

Rejections based on adjustment error (National Adjustment of 2011 => ‘h’ Reject code)

Orthometric Height Changes (mm)

Orthometric Height Changes (mm)

Large error points (‘H’ Reject)

Distribution of OPUSDBBM12

Distribution of OPUSDBBM12

MMLSC for CONUS with andwithout (w/o) OPUSDBBM12

GEOID12 with OPUS

GEOID12 without OPUS

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 GEOID12 hts.

Inverse Distance Plot to Control Data (Interpolation Gap Magnitude)

Inverse Distance Plot to Control Data (Interpolation Gap Magnitude)

An additional 6,000 points?

GEOID12 – GEOID09

GEOID12 – GEOID03 SameScale as 12-9

Summary• GEOID12 is complete for all regions• It converts between NAD 83 (**11) and the

local vertical datum (NAVD 88 in CONUS)• Modeling is much the same as before (MMLSC)• Incorporation of data in Mexico and

OPUSDBBm12 is new and has had an impact• Error maps will be available to provide

estimated errors along with geoid heights

Questions?

• Geoid Models Page:– http://www.ngs.noaa.gov/GEOID/

• GRAV-D Page:– http://www.ngs.noaa.gov/GRAV-D/

• Geoid Team: 301-713-3202 – Dan Roman (x161), Yan Wang (x127), Xiaopeng Li

(x210)

So … What Went Wrong?• Erroneous Data– VTDP exclusion region – what’s in/out? (MS, LA)– Transposed numbers (AL)– Recent adjustment and superseding data (WI)– Miscoded error flags (Canada)– Judgment call – keep or reject? (OK)

• Miscommunication/Misunderstanding– No-check GPS: NGSIDB vs. OPUS-DB (TX)– Hybrid to use minimal number of points (LA)

What Went Wrong:A Picture’s Worth a 1000 Words

What Went Wrong:Erroneous Data & Judgment Calls

PID Name StateEllipsoidal Height (m)

Orthometric Height (m)

Rejected from Modeling? CHANGE (m)

Ellipsoidal Height (m)

Orthometric Height (m)

Rejected from Modeling? Comments

Change orthometric height to published leveled value (do not use VTDP value)1 BJ0021 F 207 LA -12.789 14.224 NO OH: 0.129 -12.789 14.353 NO Outside VTDP exclusion area; use published value instead2 BJ0026 H 207 LA -13.742 13.335 NO OH: 0.132 -13.742 13.467 NO Outside VTDP exclusion area; use published value instead3 BJ0055 V 207 LA -15.691 11.516 NO OH: 0.098 -15.691 11.614 NO Outside VTDP exclusion area; use published value instead4 BW0051 E 208 LA -12.149 14.767 NO OH: 0.093 -12.149 14.860 NO Outside VTDP exclusion area; use published value instead5 BX0822 OPUS :U 238 LA -4.805 21.936 NO OH: 0.046 -4.805 21.982 NO Outside VTDP exclusion area; use published value instead6 BX0916 Q 239 LA -2.543 23.346 NO OH: 0.572 -2.543 23.918 NO Outside VTDP exclusion area; use published value instead7 CO1081 L 251 MS 55.539 82.182 NO OH: 0.630 55.539 82.812 NO Outside VTDP exclusion area; use published value instead8 DM5373 COUNTY ENG OFFICE CORS ARPAL 238.544 263.305 YES OH: 4.320 238.544 267.625 NO Wrong Orthometric height posted; value corrected to fix 4.3 m bust9 NG0372 RACINE WI 161.637 196.386 NO OH: 0.024 161.637 196.41 NO Incorrect OH loaded in NGSIDB10 NH0083 VEEN WI 259.555 293.637 NO OH: 0.032 259.555 293.669 NO Incorrect OH loaded in NGSIDB11 PM0119 AIRPORT WI 162.024 198.146 NO OH: 0.047 162.024 198.193 NO Incorrect OH loaded in NGSIDB12 PO0408 D 125 WI 173.401 203.859 NO OH: 0.007 173.401 203.866 NO Incorrect OH loaded in NGSIDB

Reject in GPSBM list1 BH3160 49 11 AL -22.709 5.734 NO 'S' reject code -22.709 5.734 YES Inside VTDP exclusion area; reject because large sigma and secondary2 BH3161 49 12 AL -24.751 3.693 NO 'S' reject code -24.751 3.693 YES Inside VTDP exclusion area; reject because large sigma and secondary3 AT0681 876 1724 C TIDAL LA -23.228 0.769 NO 'S' reject code -23.228 0.769 YES Inside VTDP exclusion area; reject because near primary only station4 AT0760 V 375 LA -25.230 0.799 NO 'S' reject code -25.230 0.799 YES Inside VTDP exclusion area; reject because does not match nearby neighbors5 AU0174 VERDUN LA -23.759 1.928 NO 'S' reject code -23.759 1.928 YES Inside VTDP exclusion area; reject because large sigma and secondary6 AU0178 J 168 LA -22.741 2.846 NO 'S' reject code -22.741 2.846 YES Inside VTDP exclusion area; reject because large sigma and secondary7 AU0189 TECHE LA -23.654 1.987 NO 'S' reject code -23.654 1.987 YES Inside VTDP exclusion area; reject because large sigma and secondary8 AU0245 T 298 LA -24.199 1.295 NO 'S' reject code -24.199 1.295 YES Inside VTDP exclusion area; reject because large sigma and secondary9 AU1117 LAROSE LA -23.085 1.928 NO 'S' reject code -23.085 1.928 YES Inside VTDP exclusion area; reject because large sigma and secondary10 AU1300 H 233 LA -24.543 0.352 NO 'S' reject code -24.543 0.352 YES Inside VTDP exclusion area; reject because large sigma and secondary11 AU1304 M 233 LA -23.541 1.255 NO 'S' reject code -23.541 1.255 YES Inside VTDP exclusion area; reject because large sigma and secondary12 AU1307 Q 233 LA -24.257 0.500 NO 'S' reject code -24.257 0.500 YES Inside VTDP exclusion area; reject because large sigma and secondary13 AU1314 X 233 LA -21.401 3.150 NO 'S' reject code -21.401 3.150 YES Inside VTDP exclusion area; reject because large sigma and secondary14 AU1317 Y 233 LA -24.224 0.300 NO 'S' reject code -24.224 0.300 YES Inside VTDP exclusion area; reject because large sigma and secondary15 AU1396 F 227 LA -24.090 1.301 NO 'S' reject code -24.090 1.301 YES Inside VTDP exclusion area; reject because large sigma and secondary16 AU1399 ARSENAUX LA -24.242 1.098 NO 'S' reject code -24.242 1.098 YES Inside VTDP exclusion area; reject because large sigma and secondary17 AU1404 K 227 LA -23.828 1.422 NO 'S' reject code -23.828 1.422 YES Inside VTDP exclusion area; reject because large sigma and secondary18 AU1406 L 227 LA -24.251 0.934 NO 'S' reject code -24.251 0.934 YES Inside VTDP exclusion area; reject because large sigma and secondary

GEOID12 GEOID12A

19 AU1418 S 227 LA -23.847 1.284 NO 'S' reject code -23.847 1.284 YES Inside VTDP exclusion area; reject because large sigma and secondary20 AU1424 T 227 LA -22.170 2.924 NO 'S' reject code -22.170 2.924 YES Inside VTDP exclusion area; reject because large sigma and secondary21 AU1433 Y 227 LA -22.945 2.203 NO 'S' reject code -22.945 2.203 YES Inside VTDP exclusion area; reject because large sigma and secondary22 AU1440 T 221 LA -23.962 1.142 NO 'S' reject code -23.962 1.142 YES Inside VTDP exclusion area; reject because large sigma and secondary23 AU1505 B 233 LA -22.304 2.839 NO 'S' reject code -22.304 2.839 YES Inside VTDP exclusion area; reject because large sigma and secondary24 AU1507 D 233 LA -22.878 2.259 NO 'S' reject code -22.878 2.259 YES Inside VTDP exclusion area; reject because large sigma and secondary25 AU1508 E 233 LA -23.322 1.717 NO 'S' reject code -23.322 1.717 YES Inside VTDP exclusion area; reject because large sigma and secondary26 AU2085 T 359 LA -22.814 2.324 NO 'S' reject code -22.814 2.324 YES Inside VTDP exclusion area; reject because large sigma and secondary27 AU2087 V 359 LA -23.059 2.056 NO 'S' reject code -23.059 2.056 YES Inside VTDP exclusion area; reject because large sigma and secondary28 AU2089 W 359 LA -24.508 0.465 NO 'S' reject code -24.508 0.465 YES Inside VTDP exclusion area; reject because large sigma and secondary29 AU2090 X 359 LA -23.355 1.854 NO 'S' reject code -23.355 1.854 YES Inside VTDP exclusion area; reject because large sigma and secondary30 BJ2124 28 A 013 LA -15.764 11.438 NO 'S' reject code -15.764 11.438 YES Inside VTDP exclusion area; reject because large sigma and secondary31 BJ2147 D 171 LA -16.803 9.973 NO 'S' reject code -16.803 9.973 YES Inside VTDP exclusion area; reject because large residual, VTDP rate suspect32 BJ2167 Y 266 LA -18.519 8.243 NO 'S' reject code -18.519 8.243 YES Inside VTDP exclusion area; reject because large sigma and secondary33 BK0159 X 267 LA -22.996 4.112 NO 'S' reject code -22.996 4.112 YES Inside VTDP exclusion area; reject because of large residual and rank34 BK0182 416 LA -21.288 6.063 NO 'S' reject code -21.288 6.063 YES Inside VTDP exclusion area; reject because large residual, no rate validation35 BK1611 10 V 27 LA -22.301 4.840 NO 'S' reject code -22.301 4.840 YES Inside VTDP exclusion area; reject because large sigma and secondary36 BW0007 E 254 LA -10.488 16.338 NO 'S' reject code -10.488 16.338 YES Inside VTDP exclusion area; reject because opposite sign resid of neighbor37 AJ6426 ADDICKS 1795 CORS ARP TX 4.035 31.500 NO 'S' reject code 4.035 31.500 YES Reject; duplicate CORS tied only with old GPS vectors38 AF9213 ENID RESET TX 357.109 385.210 NO 'S' reject code 357.109 385.210 YES Reject; duplicate CORS tied only with old GPS vectors39 AB6370 LAKE HOUSTON CORS L1 OK -7.137 20.220 NO 'S' reject code -7.137 20.220 YES Reject due to large residual and superseded 3rd BM40 BH3164 49 15 AL -13.221 15.279 NO 'S' reject code -13.221 15.279 YES Inside VTDP exclusion area; reject at request of AL representatives41 BH3165 49 16 AL -14.151 14.339 NO 'S' reject code -14.151 14.339 YES Inside VTDP exclusion area; reject at request of AL representatives42 EF0792 B 182 AL 148.544 175.25 NO 'S' reject code 148.544 175.22 YES Near DM2662 with a 11 cm difference; keep DM2662 and drop this one

Change ellipsoid height to OPUS value1 DO0454 C 281 TX 353.930 383.465 NO 353.930 383.465 YES Single shot-no check GPS from 1995 - 50 cm error2 DO0454 OPUS: C 281 TX Not Previously Used YES 354.431 383.465 NO Still fills interpolation void

Duplicate station in GPSBM file; delete one with OHT = 35.664 m (keep one with ADJUSTED source)1 BK1060 A 16 LA 8.608 35.664 NO 'S' reject code 8.608 35.664 YES Outside VTDP Exclusion area; reject VTDP Keep/Add value2 BK1060 A 16 LA 8.608 35.994 NO Keep only this 8.608 35.994 NO Outside VTDP Exclusion area; keep ADJUSTED Value

Currently rejected OPUS points to remain rejected (but has ortho height change)1 BH1732 OPUS :21 D 2 D AL -26.488 1.756 YES OH: -0.075 -26.488 1.681 YES Inside VTDP exclusion area; continue to reject but change VTDP orthometric height

Add new point not originally in GEOID121 DL7331 FOLEY CORS ARP AL Not Previously Used YES ADD NEW 4.461 32.259 NO Missed CORS site from first round; should have been included

EH: 0.501

What Went Wrong:Erroneous Data & Judgment Calls

What Went Right?• Big changes in Alexandria, LA & Meridian, MS

were reported shortly after GEOID12’s release• These were quickly checked and GEOID12 was

found to be consistent with the control data• The control data (GPSBM2012) were then re-

checked and a number of errors detected• Notices went up quickly & GEOID12 pulled• A new SOP was developed for a more public

vetting of the final product (Beta release)

There are Valid Big Changes

Ignore changes outside CONUS

VTDP region does see 50 cm change

Can see the effect of 3”-5’ RTM in the mountains

200-400 km features are due to GOCE in USGG2012

Bigger Differences with GEOID03

GEOID03 built on USGG2003

USGG2003 built using EGM96

EGM96 had no GRACE data

Most significant changes are all offshore or OCONUS

Note: same color scale as before

Coming Soon: Error Maps …

GEOID03 made using a Cholesky Decomposition

Rigorous LSC was used in GEOID12A

This ensured we had a var-cov matrix to estimate errors on a regular grid

This means errors can be provided with geoid heights

… Minimum Distance to Control Data

One of the main factors affecting errors is distance to control

This plot will provide the distance to the closest point

This provides an estimate of interpolation error impact

Near Term Goals• DEFLEC12A (made from GEOID12A)• USDOV2012 (made from USGG2012)• Error and interpolation grids– Online interpolation geodetic tool– OPUS results

• Updates to FAQ and Technical Details• Paper, likely on GEOID09, USGG2012,

GEOID12 & GEOID12A