Oky Doky...I have been playing with the new OPUS_Beta NAD83(2011) program this weekend. Now because 'we' are transitioning over to NAD83(2011) from NAD83(CORS96) anyway, I selected a station that we have used extensively on a project that 'we' are trying to finish up in the next few weeks (as a test case).
This station is a 3¼ inch Brass Cap attached to a 2½ inch steel pipe 24 inches long, and firmly set in the ground back in 2004.
There were nine observations (I might be missing one or two) between March 9th 2011 and June 22nd 2011 (there are also a couple more this month that I don't have yet). ANYWAY, nine should be more than enough to accomplish the task at hand.
I ran each observation through OPUS_Beta and then extracted the vector data (dX,dY,dZ, rms, & correlations) out of the G-FILES (extended output), along with the IGS08 'day of observation' Coordinate estimates of the CORS sites (I used the same three CORS in all submissions, all of which are PBO Stations ranging from 140Km to 220Km distant). All of the RAW OPUS solutions looked really good, with X/Y/Z peak-peak variance less than 2 centimeters in all cases, and the majority under 1 centimeter.
I then assigned (somewhat arbitrary) 0.003m rms values to these CORS X/Y/Z coordinate estimates and ran each solution through COLUMBUS holding the CORS as partial fixities. The resulting IGS08 'day of observation' Coordinate estimates where then transformed to NAD83(2011) Epoch 2010.0 via HTDP 3.1. I then did a “Zero-Baseline Adjustment” in COLUMBUS, using NAD83(2011) LSA coordinate estimates as partial fixities, and the covariance matrix's in the Zero-Baseline vectors.
The results are tabulated below (UTM Coordinates and NAVD88 heights in METERS):
RAW OPUS-Beta by 'day of year' with observation duration, followed by the arithmetic mean and the final LSA adjusted values.
Day___Northing_____Easting____NAVD88___Time_
068 4,482,484.652 385,632.822 1,520.907 08h38m
075 4,482,484.654 385,632.824 1,520.897 06h32m
114 4,482,484.649 385,632.825 1,520.895 08h28m
115 4,482,484.656 385,632.827 1,520.903 10h26m
124 4,482,484.649 385,632.822 1,520.901 11h10m
131 4,482,484.644 385,632.827 1,520.897 08h42m
159 4,482,484.654 385,632.818 1,520.905 08h40m
166 4,482,484.654 385,632.828 1,520.906 09h14m
173 4,482,484.653 385,632.825 1,520.905 08h38m
Ave 4,482,484.652 385,632.824 1,520.902 80h28m
LSA 4,482,484.647 385,632.824 1,520.894 80h28m
The LSA “answer” returned the following solution:
X -1847671.15319 +0.000000794
Y -4494045.89415 +0.000000294 +0.000001385
Z +4120084.87395 -0.000000008 -0.000000020 +0.000001493
An awful lot of work for very little return to say the least.
I figure that I can “call” this one “sub-centimeter” and sleep well tonight.
I LOVE this new Multiyear Solution the NGS is just completing!
Loyal
I wonder how much of the difference in coordinates is tribrach sighting and bubble error or fixed height bubble and rod straightness. You killed it.
Joe
Certainly "some" of it for sure!
All of the observations were done with a heavy duty SECO Fixed Height Rod/tripod set to 1.5 meters w/a Trimble Zephyr Geodetic (same gear as below, but I don't have the pictures on this point yet).
Over the next few months, I will be submitting several (probably NOT ALL) of these observations to OPUS_DB (and a butt-load of others).
Loyal
Wow, Loyal, that is really great! I took a look at the OPUS and HTDP pages hoping to catch a glimpse of these updates, but didn't notice anything new. Are these available to the public yet?
Nick
The OPUS Beta program can be found here:
http://beta.ngs.noaa.gov/OPUS/
It's still beta, so use at your own risk.
HTDP 3.1 has been around for a over a year:
http://www.ngs.noaa.gov/TOOLS/Htdp/Htdp.shtml
NAD83(2011) is a straight identity function (NAD83[CORS96/NSRS2007] to ITRF2000 to ITRF2005 to ITRF2008), just the Epoch has changed (from 2002/2007 to 2010.0000).
Loyal
You could probably get the solution even tighter....
Like down to the millisquench level...if you would get rid of that TOPCON tripod under that Trimble antenna!!!
At least sand off the word Topcon...or spray paint over it....
Or use magic marker...something...
😛
You could probably get the solution even tighter....
Is there an offset between Topcon and Trimble tripods, like there is for prisms? 😉
You could probably get the solution even tighter....
I thought Trimble owned Seco. If so, then that is actually a Trimble tripod with Topcon painted on it.
SECO gear....
All of the SECO gear that I have (and the county gear above), were built BEFORE July of 2008, so there ISN'T a $500/year charge to keep them working properly!
🙂
Loyal
SECO gear....
That may be true, Loyal< but imagine how MUCH better they would work IF you did pay that support fee...and if they did say Trimble on them.... 🙂
I dunno Tom...
I have yet to see ANYTHING with Trimble written on it, that worked any better (or any worse), than comparable gear of another color. The only REAL difference that I have ever seen, is PRICE.
Don't get me wrong, Trimble is great gear, I just think that it's overrated (and overpriced).
Loyal
Loyal
What were the length of occupations? My results are much improved when I occupy for 8 hrs rather than anything shorter.
Great results anyway you cut it though!
Last column of his copy and paste...
John,
As Joe indicated, the observation duration is the last column. The default font used by Beerleg doesn't really lend itself to tabulated data very well (and I'm to ignorant to know how to change it).
Only one observation was less than 8 hours (day 075, March 16 @ 6 hours and change), the rest are all 8-11 hours (mostly 8ish).
When I am working solo, my "base" observations pretty much 10-12 hours, with a few in the 30-50 hour range (VERY FEW).
Loyal
John,
Well I guess I wouldn't see the nose on my face if it wasn't glued on!
John,
I have that problem too (and just noticed that I spelled too wrong above).
Oh well, I guess that's just too darn bad.
🙂
Loyal
