RTX

I'm a big advocate of using RTX. It's been a while, we are mostly working with legacy control, but when updating TBC this summer some processing has been wonky. For a sanity check, we collected a days worth of data on a base yesterday. This project has a clash of NAD83 positions. GPS originally was collected in the late 1990's in the area on the east portion of the project in NAD83(93), then later about 2015 a different unconnected job was done using NAD83(2011) for the westerly portion. Needless to say as they merge there is a "miss" which comes out to .2', mostly in the Latitudes. 

I send the static file to RTX, not wanting to have that position in my working file I open up a blank file and keep it there. All I want to see is the LLH numbers. The LLH numbers from RTX are 2' in the Lat 5' in the Long. I immediately suspect that they are ITRF numbers. I send it to OPUS and it comes back with both NAD83 and ITRF. ITRF matches my RTX solution less than a cm. Same with NAD83, it matches my 2015 position less than a cm. 

The changes to 2020 are underway. 

I don't have much of an issue converting an ITRF2020 (2026.6928) value to NAD83(2011). But, it's going be interesting as we move forward with users that aren't as up to speed. There is a report in TBC explaining that the LLH coordinates are ITRF, I have not found a way to get the NAD83 values in TBC yet.

Another interesting number is the vertical, the new positions are 2.4' lower than NAVD88, almost precisely the 88 to 29 shift. HMMMM. 

I will also be interested to see how fast the ITRF numbers shift. I really think that's going to be a messy situation.