The july issue of PSM has an article on investigating Geoid 09 in TN. link
It was an interesting read and the author did an excellent job of framing the issue.
As I read further into the article the concern seemed focused on the published ellipsoidal height of PID FD1646. There seems to be little concern with respect to the published NAVD88 height. So the question raised in my mind was what vertical order is this station? Answer: FD1646 VERT ORDER - THIRD
FD1646.The orthometric height was determined by differential leveling
FD1646.and adjusted in August 1996.
FD1646.The height was determined by precise leveling from only one NSRS
FD1646.bench mark. This was not adequate "tie leveling" to NSRS and was
FD1646.allowed ONLY to validate the GPS-derived height.
FD1646.WARNING-GPS observations at this control monument resulted in a GPS
FD1646.derived orthometric height which differed from the leveled height by
FD1646.more than one decimeter (0.1 meter).
Has it occurred to anyone that the NAVD88 published height might be off by the amount in question? How does this 3rd order mark relate to first order marks around it? Does this truly demonstrate a problem with Geoid 09? The author does close out with a good point. Check the Geoid against known heights. But in my book you start with 1st order stability A or B and work your way down.
Okie dokey, try this one.....
DATABASE = ,PROGRAM = datasheet, VERSION = 7.87.2
1 National Geodetic Survey, Retrieval Date = JULY 7, 2011
CP3432 ***********************************************************************
CP3432 CBN - This is a Cooperative Base Network Control Station.
CP3432 DESIGNATION - Y 362
CP3432 PID - CP3432
CP3432 STATE/COUNTY- MS/HINDS
CP3432 USGS QUAD - JACKSON (1998)
CP3432
CP3432 *CURRENT SURVEY CONTROL
CP3432 ___________________________________________________________________
CP3432* NAD 83(2007)- 32 18 07.27528(N) 090 09 42.49919(W) ADJUSTED
CP3432* NAVD 88 - 80.240 (meters) 263.25 (feet) ADJUSTED
CP3432 ___________________________________________________________________
CP3432 EPOCH DATE - 2002.00
CP3432 X - -15,239.272 (meters) COMP
CP3432 Y - -5,396,260.043 (meters) COMP
CP3432 Z - 3,388,815.285 (meters) COMP
CP3432 LAPLACE CORR- -1.35 (seconds) DEFLEC09
CP3432 ELLIP HEIGHT- 53.959 (meters) (02/10/07) ADJUSTED
CP3432 GEOID HEIGHT- -26.30 (meters) GEOID09
CP3432 DYNAMIC HT - 80.151 (meters) 262.96 (feet) COMP
CP3432
CP3432 ------- Accuracy Estimates (at 95% Confidence Level in cm) --------
CP3432 Type PID Designation North East Ellip
CP3432 -------------------------------------------------------------------
CP3432 NETWORK CP3432 Y 362 0.31 0.49 1.35
CP3432 -------------------------------------------------------------------
CP3432 MODELED GRAV- 979,524.1 (mgal) NAVD 88
CP3432
CP3432 VERT ORDER - FIRST CLASS II
CP3432
CP3432.The horizontal coordinates were established by GPS observations
CP3432.and adjusted by the National Geodetic Survey in February 2007.
CP3432
CP3432.The datum tag of NAD 83(2007) is equivalent to NAD 83(NSRS2007).
CP3432.See National Readjustment for more information.
CP3432.The horizontal coordinates are valid at the epoch date displayed above.
CP3432.The epoch date for horizontal control is a decimal equivalence
CP3432.of Year/Month/Day.
CP3432
CP3432.The orthometric height was determined by differential leveling and
CP3432.adjusted in February 1994.
CP3432.WARNING-GPS observations at this control monument resulted in a GPS
CP3432.derived orthometric height which differed from the leveled height by
CP3432.more than one decimeter (0.1 meter).
CP3432
CP3432.Photographs are available for this station.
CP3432
CP3432.The X, Y, and Z were computed from the position and the ellipsoidal ht.
CP3432
CP3432.The Laplace correction was computed from DEFLEC09 derived deflections.
CP3432
CP3432.The ellipsoidal height was determined by GPS observations
CP3432.and is referenced to NAD 83.
CP3432
CP3432.The geoid height was determined by GEOID09.
CP3432
CP3432.The dynamic height is computed by dividing the NAVD 88
CP3432.geopotential number by the normal gravity value computed on the
CP3432.Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45
CP3432.degrees latitude (g = 980.6199 gals.).
CP3432
CP3432.The modeled gravity was interpolated from observed gravity values.
CP3432
CP3432; North East Units Scale Factor Converg.
CP3432;SPC MS W - 310,651.482 716,154.068 MT 0.99995322 +0 05 30.0
CP3432;SPC MS W - 1,019,195.74 2,349,582.14 sFT 0.99995322 +0 05 30.0
CP3432;UTM 15 - 3,577,452.169 767,247.395 MT 1.00048085 +1 31 03.3
CP3432
CP3432! - Elev Factor x Scale Factor = Combined Factor
CP3432!SPC MS W - 0.99999153 x 0.99995322 = 0.99994475
CP3432!UTM 15 - 0.99999153 x 1.00048085 = 1.00047237
CP3432
CP3432 SUPERSEDED SURVEY CONTROL
CP3432
CP3432 ELLIP H (03/26/02) 53.924 (m) GP( ) 4 2
CP3432 ELLIP H (07/24/97) 53.945 (m) GP( ) 2 1
CP3432 NAD 83(1993)- 32 18 07.28973(N) 090 09 42.49556(W) AD( ) 1
CP3432 NAD 83(1993)- 32 18 07.27511(N) 090 09 42.49927(W) AD( ) A
CP3432 ELLIP H (01/12/94) 54.055 (m) GP( ) 3 1
CP3432 NAVD 88 (07/24/97) 80.24 (m) 263.3 (f) LEVELING 3
CP3432 NAVD 88 (01/12/94) 80.4 (m) 264. (f) GPS OBS
CP3432
CP3432.Superseded values are not recommended for survey control.
CP3432.NGS no longer adjusts projects to the NAD 27 or NGVD 29 datums.
CP3432.See file dsdata.txt to determine how the superseded data were derived.
CP3432
CP3432_U.S. NATIONAL GRID SPATIAL ADDRESS: 15SYR6724777452(NAD 83)
CP3432_MARKER: F = FLANGE-ENCASED ROD
CP3432_SETTING: 59 = STAINLESS STEEL ROD IN SLEEVE (10 FT.+)
CP3432_SP_SET: STAINLESS STEEL ROD
CP3432_STAMPING: Y 362 1992
CP3432_MARK LOGO: NGS
CP3432_PROJECTION: FLUSH
CP3432_MAGNETIC: N = NO MAGNETIC MATERIAL
CP3432_STABILITY: A = MOST RELIABLE AND EXPECTED TO HOLD
CP3432+STABILITY: POSITION/ELEVATION WELL
CP3432_SATELLITE: THE SITE LOCATION WAS REPORTED AS SUITABLE FOR
CP3432+SATELLITE: SATELLITE OBSERVATIONS - April 28, 2009
CP3432_ROD/PIPE-DEPTH: 12.2 meters
CP3432_SLEEVE-DEPTH : 6.1 meters
CP3432
CP3432 HISTORY - Date Condition Report By
CP3432 HISTORY - 1992 MONUMENTED NGS
CP3432 HISTORY - 19930303 GOOD NGS
CP3432 HISTORY - 19930401 GOOD NGS
CP3432 HISTORY - 20000201 GOOD NGS
CP3432 HISTORY - 20000501 GOOD NGS
CP3432 HISTORY - 20020807 GOOD JCLS
CP3432 HISTORY - 20040315 GOOD COMPA
CP3432 HISTORY - 20050525 GOOD JCLS
CP3432 HISTORY - 20070814 GOOD JCLS
CP3432 HISTORY - 20070814 GOOD JCLS
CP3432 HISTORY - 20080320 GOOD INDIV
CP3432 HISTORY - 20090428 GOOD JCLS
I identified three basic questions I was able to answer:
Question 1: My GPS receiver provides what information?
Answer: ?Latitude, longitude, and ellipsoid height. Everything else is only a conversion by the software we use.
"""
the question i have for the author, or others is this:
gps is realized in X,Y,Z (cartesian format), not lat, lon, height, right?
lat, lon, height is also a conversion by the software we use.
Eddie,
You are correct!
The bigger issue (IMO) is whether or not "you" (not you Eddie) KNOW what Datum (or Realization/Reference Frame) those XYZs are related to. That depends a LOT (actually entirely) on just how you configured the survey, what "you" (or the RTN operator) used for constraints.
This is going to be interesting later this month when NAD83(2011) hits the bricks.
I hear (but don't know for sure) that there will be a GEOID-2012 (GEOID12).
Loyal
