What is the best way to convert California state plane zone 6 coordinates from CA HPGN epoch 1991.35 to NAD 83 (CSRS2007) epoch 2011? Or in more general terms, how to convert HARN or HPGN to just about anything else more recent and useful?
This is just for my own personal hobbyist type fun and isn't someone's homework, so it's okay to answer. 🙂
If you're interested, my example is control monument "ROS14236 PT 2029" in San Diego county. The SANGIS Control_Monuments shape file lists this as being located at CA HPGN 1991.35 Northing 2002283.6730 (sft), Easting 6312382.0930 (sft). I measured it today as being at NAD 83 (CSRS2007) epoch 2011 Northing 2002285.6684 (sft), Easting 6312380.3959 (sft) with an ellipsoid height of 270.545 (m).
Running the former through HTDP to account for velocity only and comparing the result to what I measure as the latter today, the predicted coordinates end up about 0.053 (sft) off in Northing and about 0.133 (sft) off in Easting from the measured ones. I figure that is because either 1) there's a significant datum shift between HPGN and CSRS2007 and that's about how much it is or 2) this result is within my error bars (i.e, I'm not collecting data for long enough). I'm measuring it with 300 epochs (five minutes) of CRTN RTK with P478 as the base. I'd collect several hours of static data and post process it for better results, but my equipment would likely get run over, stolen or vandalized if I tried. I got some nasty stares and a suspicious drive by as it is 🙁
I tried to do this conversion using the NGS GEOCON 2.0 beta online utility which claims to do HARN datum conversion, but it just core dumps on me every time. Can anyone out there do this conversion and post the results?
HTDP is a model. It has error, or perhaps imprecision is a better word. The 1991 coordinates are based on measurements from some network. Those measurements have error as do the position of the points in the network.
It's a prediction, an estimate. I suspect the estimate is better between more recent adjustments and will continue to improve with better resolution (more data points in HTDP) and more accurate networks.
And of course you are correct that you have error in your measurement and the CRTN has error in the network. How far was the rover from the CRTN reference station that you were using?
AD,
I haven't had much luck with GeoCon 2.0 Beta. Did you try v1.1?
This from Dru Smith in this thread:
https://surveyorconnect.com/threads/datum-reference-frames.322252/
NADCON will convert NAD 27 lat/lon to NAD 83(1986) lat/lon
NADCON will also convert NAD 83(1986) lat/lon to NAD 83("HARN") lat/lon
GEOCON v1.0 or v1.1 will convert NAD 83("HARN") lat/lon/h to NAD 83(NSRS2007) lat/lon/h
GEOCON11 v1.0 or v1.1 will convert NAD 83(NSRS2007) to NAD 83(2011)
Dave
Shawn Billings, post: 358773, member: 6521 wrote: How far was the rover from the CRTN reference station that you were using?
About 8.584 kilometers according to the data collector.
Without knowing anything else I'd estimate your 2D error to be about 5cm at 95% just in the vector from the CRTN. Could be less. I'm using the industry rule of thumb of 1cm + 1 ppm at 1 sigma. I think that's probably pessimistic, but helps make the point.
You can find answers here:
Space, Time, and Datum Forensics: A Geodetic Workshop
By
Michael Dennis
and sponsored by
The Oregon GPS UserÛªs Group
What do you do when your horizontal control monuments are NAD 83 (1998), your field work is NAD 83 (2011) epoch 2010.00, and the client requires NAD 83 (1991) deliverables? Which geoid model should be used with the different horizontal datums? How do you set up a long-term project in light of the fact that new horizontal (geometric) and vertical datums will be defined and adopted by NGS within the next 8 years? How does all this work with the Oregon Coordinate Reference System low-distortion projections? What is the difference between NAD 83, IGS08, ITRF2008, and WGS 84? What software tools are available?
For the answers to these and many more questions, Michael Dennis will be presenting an all day workshop:
When: Thursday, March 10, 2016 7:30am-4:30pm
Where: NW Eola Viticulture Center of Chemeketa C.C.
215 Doaks Ferry Rd., Salem, OR 97304
Lunch: Yes, tasty lunch is provided
Check-in: 7:30-8:30 AM (Preregistration onlyÛÓNo registration at the door)
PDH Credits: 7
First come, first served for up to 150 registrants. Cost is $75 and includes buffet style lunch. Attendees will be emailed any handout materials a few weeks before the workshop and should be self-printed prior to your attendance. No handout materials will be provided at the workshop.
Michael L. Dennis, RLS, PE, is owner of Geodetic Analysis, LLC. His firm provides geodetic and GIS consulting services, including coordinate system design, GNSS processing, control network adjustments, and survey-GIS data integration. Mr. Dennis is also a geodesist at the National Geodetic Survey currently on leave while pursuing a PhD in geomatics engineering and GIS at Oregon State University. While at NGS, Mr. Dennis managed the National Adjustment of 2011 Project, and as a consultant he was instrumental in helping define the low distortion projections used for the Oregon Coordinate Reference System.
Questions: johnminor3537@gmail.com or Chris Munson at chris@munson-assoc.com
Send one registration per person to: Chris Munson 233 Southwest Wilson Ave., Ste.5, Bend, OR 97702
Make Checks payable to: Oregon GPS Users Group
OGUG tax ID# 93-1282014 For map and directions: WWW.ogug.net
.............................................................(Cut)...............................................................................
Name:_____________________________________________________________________
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Sounds good except for the location. Some group in San Diego please host one of these workshops. 🙂
Write the plane ticket off as a business expense. Beats the heck out of groping your way through projects hoping you are doing it right. A mistake could cost way more than the plane ride. Just say'in.
