NATREF Sample datasets

It's going to be interesting for sure. The last opus and TBC data I got from OPUS and RTX declared the ITRF 2020 EPOCH to be 2026.6928.

Does that imply that there are 6928 EPOCH in 2026? or is that nomenclature indictive of something else?

AI declared that 2026.6928 means data was collected Sep 21, 2026 at 15:52:41 UTC.

The data was collected Sep 11, 2026 so that didn't help much. 

I will be looking at some control points and shifts through the next few months. I'm in a stable part of the lower 48, Cali and Hawaii will be flying along I suppose. 

@mightymoe 

By my calculations the 2026.6928 would be 10 September 26 at around 9 pm UTC or 3 pm MDT.

I am not sure of the conventions they are using for that decimal part; my only check is that at 0 hrs UTC on 01 January 2026 my calculation method shows the epoch as 2026.0000.

No clue if that decimal part indicates the beginning of the observation, the end, or something in between?

Or mayhaps it refers to the time of the files from the reference station?  Dunno, probably not significant anyway.

GB

OPUS (and RTX) return ITRF2020 at the current epoch. The ".6928" is a fraction of a year. I maintain that 2 (or maybe 3) decimals is sufficient to define a fractional part of the year, so it could be 2026.69 imo

The transformation is to bring the ITRF2020 current epoch position to what NATREF is going to use (for now)...2020.00.

The parameters are the euler pole parameters (around the ECEF XYZ axes in mas (milli arc seconds) per year. This accounts for the motion of the rigid part of the US with respect to the ITRF reference frame. 

I am confused on the proper signs for the three parameters and knowing a sample would tell me if I am assuming correctly. 

I am not yet clear on what happens on the "non-stable" parts of the NA plate, west of the red line below...

This is the OPUS for the point, as you can see the EPOCH is 2026.6928, which is the same as RTX. I didn't keep that coordinate since I'm not concerned in ITRF only NAD83 because this was a check on existing control and unfortunately RTX didn't send the NAD83 number. 

@mightymoe If you take the RTX ITRF current epoch coordinate and run it through HTDP you will get the (AFAIK) transformation that OPUS is doing.

I'm finding that the NCAT Beta tool is still under active development. The latest September 15 update did resolve some of the issues I was seeing previously but there are still some gaps, based on my efforts so far they can be summarized as:

• No general US epoch-to-epoch coordinate propagation using IFDM.
• The direct NADCON beta transformation is limited to CONUS NAD83(2011) at 2010.0 → NATRF2022 at 2020.0; other epoch combinations are not supported through that operation. So far I've only implemented the forward path, not reverse although reverse is technically feasible.
• GEOID2022 height conversion is limited to epoch 2020.0; other epochs and time-dependent geoid corrections are not supported.
• Complete, validated frame-and-height transformations are not yet available across all Alaska, Hawaii, and US territory combinations.

I've created a beta utility to help with validating the tools I'm building for a general purpose SDK. You can check it out at SGS Coordinate Transformer — Simple Geospatial Solutions Inc. if you like.

For now I'm just waiting for more relevant data, documentation, sample datasets and the ability to validate the results. 

I just did another RTX And OPUS submission on a long term DOT point. The "miss" for NAD83 was about .06'N, .07'E which is similar to what we've seen for 83(2011) on that point. The two ITRF numbers (OPUS & RTX) were almost identical .01'N, .02'E in the Lat, Long numbers. Again unfortunately RTX did not report the NAD83 number and imported as ITRF, about 4.7' from NAD83 which isn't useful for this project. Even though the project is set up based on a NAD83 State Plane Zone it showed no real error warning. Conversions will need to be calculated (outside of TBC?) to use RTX. The Epoch is 2026.72566, the extension has increased to 5 decimals from 4. 

Frankly this looks like a cluster of major proportions about to happen.

A side note the shift from NAVD88 to 2020 in the elevations is -2.34', for this location the shift from NAVD88 to NGVD29 is -2.45'. This looks like lots of fun going forward. 

https://content.govdelivery.com/accounts/USNOAANOS/bulletins/42b6ba2