Mike Thompson <miketh...@gmail.com> writes: > On Fri, Jan 8, 2016 at 9:47 AM, Colin Smale <colin.sm...@xs4all.nl> wrote: >> >> How did all the elevation data get into OSM in the first place? >> > The elevations of peaks in the US came from the GNIS import. In turn the > GNIS elevations came from the National Elevation Dataset (NED) [1], and it > mostly uses the North American Vertical Datum of 1988 [2]. The other > problem is that these are not "spot elevations" and therefore the elevation > of a peak in the GNIS does not - in most cases - match the official > elevation (the ones shown on the old USGS Topo maps and published by the > National Geodetic Survey[3]). > > [1] http://nationalmap.gov/elevation.html > [2] http://www.usgs.gov/faq/categories/9865/4921 > [3] http://www.ngs.noaa.gov/datasheets/
Perhaps it would be a good project, perhaps via maproulette, to spiff this up. It can be tricky, though, because the benchmarks on mountains are not always the exact summit -- I actually found the mark on Mt. Washburn in Yellowstone, and I don't think it matches the mountain height. But I get it that the USGS surely publishes mountain heights somehow. I do see that WGS84 heights and NAVD88 heights are off by part of a meter east coast up to 2m in Washington State. Still, I think data with those kinds of errors is far better than no data.
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