On Mon, Jul 30, 2018 at 11:39 AM Martin Koppenhoefer <dieterdre...@gmail.com> wrote: > I did not check any numbers, but I would also expect a lot of data not > following this definition. [of the ele=* tag meaining EGM96]
Uhm, yeah. I've been using NAVD88 as orthometric datum. I have the tables loaded in my GPS app, and it's what surveyors use locally. But the difference between that and EGD96 is far too small for my equipment to measure - I don't have a survey-grade GPS, or the patience for the integration time that using one requires. Entering ellipsoidal height rather than orthometric elevation, though, is Just Plain Wrong - and I bet we have a lot of data entered that way that are off by tens of metres. I further bet that two-thirds of the people reading this thread have Absolutely No Idea what we're talking about. (That isn't really a severe criticism. It's more an indictment of the sorry state of consumer-grade GPS that ordinary mappers would be forced to learn that much geodesy to get it right.) _______________________________________________ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
