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A brief synopsis of the NGS Geospatial Summit  

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John Hamilton
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I attended the NGS Geospatial Summit in Silver Spring the last two days. The main focus of the gathering was the upcoming changes to new horizontal reference frames and vertical datum in 2022. Here are my recollections of what was presented...

HORIZONTAL: There will be four new horizontal reference frames:
North American Terrestrial Reference Frame of 2022 (NATRF2022, pronounced natref 2022)
Pacific Terrestrial Reference Frame of 2022 (PTRF2022)
Mariana Terrestrial Reference Frame of 2022 (MTRF2022)
Caribbean Terrestrial Reference Frame of 2022 (CTRF2022)

All four will be based on ITRFxx (whatever the most recent xx is at the time) at a fixed epoch (possibly/probably 2020.00). The NATREF2022 will remain fixed to that epoch (until someone decides it has drifted too far away from current ITRF). There are slight rotations remaining on the fixed portion of the north american plate, those will be used to convert ITRFxx epoch XXXX.xx to NATREF2022 epoch 2020.00(?). Similar situation for the other three reference frames. There were some concerns raised by non-NGS people that maybe we should be going totally dynamic (i.e. not a fixed epoch). I imagine that NGS got a lot of feedback prior to making the decision from both sides (dynamic versus static). As we all know, most surveyors do NOT like coordinates that are constantly changing. I believe we can have it both ways, because there are accurate velocity models that enable one to convert back and forth. Of particular significance to me was an offhand comment that the new reference frames are NOT a re-adjustment in the sense that all of the passive control will not be dealt with at all. The CORS will be re-processed, and those "new" coordinates will define the frames. If you want to use passive control, you will need to apply a transformation to bring the NAD83 (2011) coordinates up to NATREF2022. At least that is the way I understood it.

BLUEBOOKING: They are working on making OPUS-Projects the way to bring user supplied data into the NSRS database (currently called bluebooking). It was not clear to me whether user processed data (i.e. processed in Trimble TBC, Leica, Topcon, etc) will still be able to be submitted. Someone on the webinar (remote viewer) did specifically ask the question about TBC, but the answer was not clear (in my opinion). To me, this is a major issue. Not all GPS needs to be observed for 2 or 4 hours or more (as is required in OPUS-Projects). I currently have a client who is observing about 20 or 30 new points to be bluebooked in a county, the baselines are short, and 60 minute observations are sufficient (processed in TBC). The data will be adjusted in ADJUST (NGS program), but I do not see the necessity for requiring all data to be processed in OPUS.

VERTICAL: The new vertical datum will be called North American-Pacific Geopotential Datum of 2022 (NAPGD2022). I didn't hear anyone pronounce that, maybe it will be NAPGID? This will be based SOLELY on a geoid model (GEOID2022) and ellipsoidal heights from the above terrestrial reference frames. No benchmarks, no leveling, no hybrid geoid. Accuracy of around 1.4 cm (?). I got that number from 1 cm ellipsoidal heights and a 1 cm geoid model (sqrt (1^2+1^2)). Of course we can still use leveling, but running between two passive marks will probably be way more accurate than the elevations on the marks, so to me that presents a problem. I am not at all clear on what will happen to bluebook leveling, I don't see a fit for that in the new datum.

As someone who does a LOT of both GPS and leveling bluebooking (observed by us and by others, where I just do the processing and submittal), this leaves some unanswered questions. I have been telling people that one advantage of bluebooking is that it gets the data into the NSRS, and whenever there is a re-adjustment (NAD83 (2007), NAD83 (2011), etc) or a new datum (NAD27 to NAD83) then the data will automatically be re-adjusted by NGS. Looks like that may not be the case.

The fact is that 5 years is NOT a long way off, so it is important to educate surveyors about what exactly this means for our future. There will be more summits, webinars, outreach, etc from NGS and others.

If any of my above recollections or assumptions are incorrect, feel free to correct me. Hopefully this will start a productive discussion......

33 Replies
Jim Frame
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Thanks for the synopsis.

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James Fleming
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Thanks...that saved me 12 unbillable hours and having to deal with the mass transit crap-shoot that is known locally as "The Red Line"

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John Hamilton
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James Fleming, post: 425476, member: 136 wrote: Thanks...that saved me 12 unbillable hours and having to deal with the mass transit crap-shoot that is known locally as "The Red Line"

Jim: I remember when Silver Spring was a cheap place to stay. Not anymore.

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MightyMoe
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Oh boy!!! Life could get really interesting. I don't see this being easily meshed into existing regulated data, but we will see. From what I've read we will get an adjustment of about -2 feet locally, placing 2020 elevations a tad higher than NGVD29.

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