HTDP, OPUS and NGS Data Sheets

[Labedzki]

I am trying to figure out this NGS program HTDP. Does anyone have any experience with this software?

I surveyed in a monument PID (DL9167) near my house. I uploaded the data to OPUS and compared the data from OPUS with the NGS Data Sheet. Below are 2 excerpts from the OPUS report and the NGS Data Sheet. Here are the steps I followed using the HTDP software:

1. When I use the NGS HTDP software, I select <3> Update positions and/or observations to a specified date.
2. Then I select <2> decimal year, and enter <2007.00>.
3. I select <1> NAD_83(2011) (North America tectonic plate fixed) and then select <1> Update positions for individual points entered interactively.
4. Enter the time in which the input positions will correspond <2> decimal year, and enter <2010.0000>, type <GPS_TEST_021411> for file name, and enter <GARFIELD> for point name.
5. I then select <1> for geodetic latitude and longitude, and enter <38,37,54.87928> for latitude and <121,20,13.16472> for longitude, and <1.561> for ellipsoid height.
6. And then I select <0> use velocity predicted by this software, then it displays the following in my file called GPS_TEST_021411:

HTDP (version 3.1) OUTPUT

UPDATED POSITIONS IN NAD_83(2011)
FROM 1-01-2010 TO 1-01-2007 (month-day-year)
FROM 2010.000 TO 2007.000 (decimal years)

OLD COORDINATE NEW COORDINATE VELOCITY DISPLACEMENT

GARFIELD
LATITUDE 38 37 54.87928 N 38 37 54.87838 N 9.20 mm/yr -0.028 m north
LONGITUDE 121 20 13.16472 W 121 20 13.16365 W -8.59 mm/yr 0.026 m east
ELLIP. HT. 1.561 1.565 -1.36 mm/yr 0.004 m up
X -2594602.196 -2594602.185 -3.80 mm/yr 0.011 m
Y -4261171.230 -4261171.261 10.28 mm/yr -0.031 m
Z 3960479.646 3960479.627 6.34 mm/yr -0.019 m

My values don’t match, why is this? I am I doing something wrong?




OPUS-RS SOLUTION REPORT

USER: nlabedzki@hotmail.com DATE: November 05, 2011
RINEX FILE: log2308w.11o TIME: 21:56:05 UTC


SOFTWARE: rsgps 1.35.1 RS43.prl 1.78 START: 2011/11/04 22:40:40
EPHEMERIS: igr16605.eph [rapid] STOP: 2011/11/04 22:56:30
NAV FILE: brdc3080.11n OBS USED: 1863 / 1944 : 96%
ANT NAME: SOKGRX1 NONE QUALITY IND. 13.70/ 0.53
ARP HEIGHT: 2 NORMALIZED RMS: 0.382


REF FRAME: NAD_83(2011)(EPOCH:2010.0000) IGS08 (EPOCH:2011.84370)

X: -2594602.188(m) 0.019(m) -2594603.011(m) 0.019(m)
Y: -4261171.196(m) 0.021(m) -4261169.917(m) 0.021(m)
Z: 3960479.637(m) 0.010(m) 3960479.616(m) 0.010(m)

LAT: 38 37 54.87973 0.011(m) 38 37 54.89265 0.011(m)
E LON: 238 39 46.83485 0.007(m) 238 39 46.77829 0.007(m)
W LON: 121 20 13.16515 0.007(m) 121 20 13.22171 0.007(m)
EL HGT: 1.529(m) 0.027(m) 0.997(m) 0.027(m)
ORTHO HGT: [Geoid Model Not Yet Available w/ NAD83 (2011).]

UTM COORDINATES STATE PLANE COORDINATES
UTM (Zone 10) SPC (0402 CA 2)
Northing (Y) [meters] 4277242.345 607358.297
Easting (X) [meters] 644750.582 2057726.887
Convergence [degrees] 1.03842165 0.41800661
Point Scale 0.99985803 0.99994570
Combined Factor 0.99985779 0.99994546



NGS DATA SHEET

DL9167 *CURRENT SURVEY CONTROL
DL9167 ___________________________________________________________________
DL9167* NAD 83(2007)- 38 37 54.87928(N) 121 20 13.16472(W) ADJUSTED
DL9167* NAVD 88 - 31.99 (meters) 105.0 (feet) GPS OBS
DL9167 ___________________________________________________________________
DL9167 EPOCH DATE - 2007.00
DL9167 X - -2,594,602.196 (meters) COMP
DL9167 Y - -4,261,171.230 (meters) COMP
DL9167 Z - 3,960,479.646 (meters) COMP
DL9167 LAPLACE CORR- 5.78 (seconds) DEFLEC09
DL9167 ELLIP HEIGHT- 1.561 (meters) (06/22/10) ADJUSTED
DL9167 GEOID HEIGHT- -30.44 (meters) GEOID09
DL9167 HORZ ORDER - B
DL9167 ELLP ORDER - THIRD CLASS II
DL9167
DL9167.The horizontal coordinates were established by GPS observations
DL9167.and adjusted by the FRAME SURVEYING AND MAPPING in June 2010.
DL9167
DL9167.The datum tag of NAD 83(2007) is equivalent to NAD 83(NSRS2007).
DL9167.See National Readjustment for more information.
DL9167
DL9167.The horizontal coordinates are valid at the epoch date displayed above
DL9167.which is a decimal equivalence of Year/Month/Day.
DL9167
DL9167.The orthometric height was determined by GPS observations and a
DL9167.high-resolution geoid model using precise GPS observation and
DL9167.processing techniques.
DL9167
DL9167.The X, Y, and Z were computed from the position and the ellipsoidal ht.
DL9167
DL9167.The Laplace correction was computed from DEFLEC09 derived deflections.
DL9167
DL9167.The ellipsoidal height was determined by GPS observations
DL9167.and is referenced to NAD 83.
DL9167
DL9167.The geoid height was determined by GEOID09.

Look forward to your response!

Thanks a bunch.

[McGee]

Try re-running the solution and go from 2007.00 to 2010.00. Because you are updating you should see your resulting position moving north and west consistent with the velocities. I did not re-run the HTDP solution; however, given the HTDP velocity of North 9.2mm per year for 3.00 years should result in a 2010.00 latitude of 38-37-54.88018 at GARFIELD. The OPUS solution returned a value of 54.87973 which is south 0.05 feet.

Giving the following error sources: (1) the effect of OPUS returning a position relative to the CORS based on a new adjustment and reference frame, (2) the HTDP velocities are based on some historic data, (3) the position of GARFIELD is based on the 2007.00 Adjustment, (4) the probable errors in the computed vectors from the nearest CORS, (5) any errors in the setup and collection of GPS data; then the difference of 0.05 feet seems reasonable.
Michael McGee

[D Ryan]

Labedzki-

I didn't read your post in detail, might help if you just summarized how much they don't match. But I did an interesting exercise last year when my HTDP results didn't appear reliable in a couple of cases. I took a 1991.35 data sheet(for instance) and a 2007.00 data sheet and used HTDP to compare positional differences. It wasn't a very good fit. Of course I'm in an area with a lack of concentrated CORS or CGPS to help refine theoretical velocities in HTDP. It's OK if you don't try and push it out too many years, but I found it was better to come up with a per year velocity and bearing via the data sheets. Helps if you keep old data sheets around.

Dave Ryan,
Humboldt County

[Rob_LS]

I suggest attending the Datums seminar-workshop March 2 at Santa Rosa College.

[dmi]

Because of the ADJUSTMENT of 1991.35, this epoch will never produce reasonable results when using HTDP. Control after that epoch date seems to work reasonably well with HTDP.

[Labedzki]

After I used the correct starting EPOCH, HTDP worked like a champ! As to be expected, differences in values occur at the 1/1000 to 1/10000 decimal places. Below is my new HTDP results and below that is my results. Thanks again for everyone's input, I greatly appreciate it.

HTDP

HTDP (version 3.1) OUTPUT

UPDATED POSITIONS IN NAD_83(2011)
FROM 1-01-2007 TO 1-01-2010 (month-day-year)
FROM 2007.000 TO 2010.000 (decimal years)

OLD COORDINATE NEW COORDINATE VELOCITY DISPLACEMENT

GARFIELD
LATITUDE 38 37 54.87928 N 38 37 54.88018 N 9.20 mm/yr 0.028 m north
LONGITUDE 121 20 13.16472 W 121 20 13.16579 W -8.59 mm/yr -0.026 m east
ELLIP. HT. 1.561 1.557 -1.36 mm/yr -0.004 m up
X -2594602.196 -2594602.208 -3.80 mm/yr -0.011 m
Y -4261171.230 -4261171.199 10.28 mm/yr 0.031 m
Z 3960479.646 3960479.665 6.34 mm/yr 0.019 m

RESULTS

DESCRIPTION LATITUDE LONGITUDE EL HGT(M) EPOCH
GARFIELD OPUS (2010.00) 38 37 54.87973 121 20 13.16515 1.529 2010.0000
GARFIELD NGS (2007.00) 38 37 54.87928 121 20 13.16472 1.561 2007.0000
INVERSE 0.057801

GARFIELD OPUS (2010.00) 38 37 54.87973 121 20 13.16515 1.529 2010.0000
GARFIELD HTDP (2010.00) 38 37 54.88018 121 20 13.16579 1.557 2010.0000
INVERSE 0.068015

GARFIELD HTDP (2010.00) 38 37 54.88018 121 20 13.16579 1.557 2010.0000
GARFIELD NGS (2007.00) 38 37 54.87928 121 20 13.16472 1.561 2007.0000
INVERSE 0.125208

NOTE: CORPSCON WAS USED TO CONVERT LATS & LONGS TO CCS83 COORDINATES, INVERSES ARE BASED ON THE CCS83 COORDS (NOT SHOWN), INVERSE UNITS US SURVEY FEET.