Dear Bill93, I'm the former Chief Geodesist, before Dr. Dru Smith & Dr. Dan Roman,and I think I can help answer your questions. Yes, indeed, you a...
John Putnam, post: 425425, member: 1188 wrote: If GEOID12B returns VIVD09 values in VI and NAVD88 values in FL, how do they make the change. Is it at...
>> "...how much difference can there be on a 10 mile long island?"A good question. To explore this I extracted GEOID12B intoa sub-grid enclosin...
Dear Larry Best,Perhaps I can help. I'm Dennis Milbert, Ph.D. I retired as the NGSChief Geodesist in 2004. My predecessor was Bill Strange, and mys...
Dear rfc, >>>Does quasi-decadal periodicity affect GPS observations?>>>Doesn't this impact the very ECEF reference system that GNSS ...
This might be more than you want, but a monograph on tensors andgeodesy is Hotine's Mathematical Geodesy. For geodynamics, I suspect you will find ma...
RalphDear Dave,First, let me say "thanks Ralph" for posting and highlightingthose notes. Also, for those interested, the Rapp/OSU Geometric Geodesy In...
GeeOddMike is correct that GRS80 is not merely an ellipsoidbut is a rotating, equipotential surface that is an ellipsoid.As such, it generates not onl...
Wink! 😉 All the best!
Dear eddym and Dave,Hi, eddym! Welcome!eddym's post represents the first definition of "datum" in thegeodetic glossary. That is, the datum is only a...
Ben,Thanks for the input. 🙂 Dave,Yes, there is the NGS Geodetic Glossary. It was a compilation of definitions found in general use -- and it prece...
Dave,Horizontal Datums and Reference FramesDave,OK, in the hierarchy:A Datum is a Reference Frame.A Reference Frame is a Datum.They both have coordina...
Dave,I know I threw a lot of material up on that post.So let me address your last comment regarding Reference Frame and crustal motion.By the IERS Con...
Dear Dave,Dave asked:"What's the difference between a horizontal datum and a reference frame?"Let's look at this in two steps. First, the relation of...
I can help.I have not read the article in question, but I have studiedthe topic."Polar Tide" is more commonly known as "Pole Tide", so Googlehits on t...
Two Different Statistical ProblemsI think I can shed a little light on this discrepency.I checked Chapter 19 of Gilhani and Wolf's Adjustment Computat...
Dear Jeff,The latest FGDC standards are found at:Look halfway down for "Geospatial Positioning Accuracy Standards"Parts 1,2, and 3 are probably what y...
Dear Hillbilly Leg,I have a short answer and a long answer to your problem.Short answer first --Yes, indeed, those error estimates are way too optimis...
Dave K.,Sun or Polaris (or any other star), the reduction procedure willyield an astronomic azimuth. The Laplace correction willprovide the differenc...
Dear Dane,Yes, you do level your GPS antenna.But, no, you don't need to consider deflection of the vertical.(The GPS data are referenced to XYZ, Earth...