A few quick comments.1. I hope that NGS will add a FAQ about the issue of what orthometric heights are provided in the Virgin Islands. I cannot find r...

While located via the link provided above, this graphic might be more helpful. Drat it's in those pesky "feet"...

Same process, different island...For tidal data on 1381 A (actually 9751381A) go to: There are other tidal benchmarks published by CO-OPS in the area ...

The two links below provide information about vertical datums and other related topics.This is a link to a tool allowing the user to find information ...

I guess I am more practical minded. Another source on relativistic geodesy relevant to the determination of potential differences is: Look at all tha...

Shawn Billings, post: 422668, member: 6521 wrote: Strange. The transformation parameters don't look like enough to produce the difference in positions...

Bill93, post: 422658, member: 87 wrote: I ran one of my RINEX files through Trimble RTX-PP and compared to what I got with OPUS-RS (rapid orbits), and...

philos, post: 422278, member: 12630 wrote: thanks you for your message,Mark Mayer : we want to start a new mining projet in africa (DRC). what i want ...

Howdy,To supplement the other postings, I provide the following verified links and some additional detail. It is possible to determine a position anyw...

Refinements...Interesting that when first envisioned it was linked to the dimensions of the earth. Now, like everything else, it has become more abstr...

Interesting history of its evolving definition... Copied from the NGS Geodetic Glossary

From:NOS HYDROGRAPHIC SURVEYS SPECIFICATIONS AND DELIVERABLESMarch 2016USDOC/NOAAThe determination of an ellipsoid height is hardly the only requireme...

The best compilation of information about different height systems is this: The quote was intended as a reminder that all geometric heighting is non-u...

Having been traveling most of the day, I did not get a change to either respond or research issues related to tidal heights and their relationship to ...

BTW, isn't Alaska part of the US?

JOHN NOLTON, post: 420254, member: 225 wrote: Above in GeeOddMike post (note: when i looked at post by this person I always thought it was " Gee Old M...

Finally remembered how to convert a TIFF to JPG. Image taken from Dr. Smith's presentation linked in prior post. Same as PDF above.

Lots of good discussion in this site's archives on the WGS84 v NAD83 v ITRF and related issues. In short, assertions that one has an WGS84 height requ...