I have been using Trimble RTX for a few years now. RTX works natively in ITRF2014 at the current epoch. They had a transformation to get to NAD83 (2011) epoch 2010.0, which by my analysis was only accurate to several centimeters, and it got worse the further west you go in the US. I found that in order to get an accurate NAD83 (2011) epoch 2010.0 coordinate it was necessary to take the ITRF2014 coordinate and run it through the NGS utility HTDP. So I developed a workflow to do it automatically. Once I had it setup the agreement of post processed RTX with static processing using CORS was sub centimeter. In fact, I was comfortable using post processed RTX now rather than going through the effort to download and process CORS for a lot of projects. And I would also run real time RTX through the process as well back in the office (I don't need coordinates in real time).?ÿ ?ÿ
I was happy to hear today that Trimble is now using HTDP in their transformation in the latest versions of Trimble Access (data collector) and TBC (office software). Now I wish NGS would update and maintain HTDP.?ÿ
I received a "RTX Report" (.pdf file) last week from one of the other consultants on a project that I am working on. There was also a 3 hour RINEX file included.
I ran the RINEX through OPUS using several different CORS combinations, and found that the 2021.01 ITRF2014 position AGREED between the several solutions (RTX & OPUS) within couple of hundredths of a foot (subcentimeter). However the NAD83 2011 (Epoch 2010.000) positions varied by 0.372 N/S & 0.186 E/W between the CORS solutions and the RTX solution!
RTX had used MORVEL56 as the "Tectonic Plate Model," whereas OPUS had obviously used HTDP.
I'm glad to see that Trimble has got on board with the NGS Model (NAD83 is afterall an NGS product.
Loyal?ÿ?ÿ
My reading of
National Geodetic Survey, 2020: Blueprint for the Modernized NSRS, Part 1: Geometric Coordinates and Terrestrial Reference Frames, NOAA Technical Report NOS NGS 62. https://geodesy.noaa.gov/PUBS_LIB/NOAA_TR_NOS_NGS_0062.pdf?ÿ
leads me to believe that HTDP is not part of future plans. See discussion starting digital,page 25...
See also discussions of Euler poles in recent NGS TMs:
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At present NCAT does not do ITRF transformations. Not sure why, since that is where we are headed. You have to go to VDatum, which makes no sense to me.?ÿ
Loyal: here is something that would interest you. I had a project that included doing surveys at 18 sites all over Montana. Each site had a base (Trimble Alloy-multi constellation) that ran for times ranging from 54 minutes up to 160 minutes. Most were around 60 minutes.?ÿ
I downloaded data from 23 CORS and processed it as a single network using precise ephemerides. The network looked like this:
Downloading and processing all of that of course was time consuming.?ÿ
I did a constrained adjustment holding the CORS. I processed all of the base data using RTX (Post processed). Here are the differences (units: meters, Delta H column is horizontal:
Not too bad, but the horizontal is worse than the vertical?ÿ
?ÿNext, I ran the RTX ITRF14 current epoch coordinates through HTDP:
Of course, no change in the vertical but significant improvement in the horizontal. Only two occupations were long enough (>120 minutes) for OPUS, so I didn't check that.?ÿ
My takeaway from this is that 60 minutes of data submitted to RTX is as good as a 4 hour OPUS solution. And not necessary to spend the time downloading CORS data for post processing.?ÿ
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@john-hamilton Interesting. Is that 60 minutes of multi-constellation data processed through RTX vs GPS-only through OPUS?
60 minutes of RTX versus GPS only (dual frequency) processed in TBC, not OPUS. RTX used GPS, Glonass, and Galileo. Not sure why, but it doesn't seem to use Beidou, even though it was present in the data.?ÿ
When referring to "Trimble RTX", make sure you note which service you are referring to. They have a post processing service for logged static data, which uses their own CORS located around the world, and a separete real-time VRS satellite based delivery system of which is a pay service.?ÿ?ÿ
@loyal Trimble RTX-PP gives you options for coordinate system, and tectonic plate to use.
Yes, but it did not previously use HTDP to transform to NAD83(2011) epoch 2010.0. I just resubmitted one of the files, the online version is still using MORVEL56, and gives the same results. I will submit via TBC (never did that before) to see what happens. It may be that the HTDP transformation is in TBC and not in the online RTX processor.?ÿ
Edit: I now sent it from TBC, and the results agree with my HTDP solution 0.000 m X, 0.000 m Y, and 0.001 m Z (ECEF). So, it appears the HTDP transformation is done in TBC (5.40) and not in the online processor.?ÿ
Maybe the reasoning is that you must have a license to do it in access or TBC, whereas the online processor is free to anyone.?ÿ
So all of my work writing a program to do the HTDP transformation was not for nothing...I prefer to upload to the online processor and have not been using the function in TBC.?ÿ
