How does a realignment of a datum actually change the model?
Hi. Newbie here. I’ve been chipping away at learning about the different datums and reference systems used in the US for survey work (I’m looking at going into surveying). I was learning about how NAD83 has changed over the years and how it has been realigned at different epochs. I’m pretty confused about what a realignment actually means and how it relates to Epoch. I think that NAD83 moves along with the NA continent, so as the years go by, monuments keep their coordinates, unlike with WGS84 and ITRF systems. However, periodically NAD83 has gone through different iterations and updates, usually relating to some year epoch. My question is; when one of these realignments happen, are the coordinates of the system itself all reset to what they were back in epoch 1984 when the coordinates looked more like a global system like WGS and come back into alignment with those systems. Or, does NAD83, continue to remain aligned with the continent and remain out of alignment with WGS 84? I imagine the coordinate system either statying with the continent or constantly being reset to the planet as a whole. What other major changes effect how the coordinates change at each realignment? I hope I’m making my questions clear. Thank you for any discussion!
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