And for those (like me) who are not up to speed on how peaks are measured…
The World Geodetic System (WGS) is a standard for use in cartography <https://en.m.wikipedia.org/wiki/Cartography>, geodesy <https://en.m.wikipedia.org/wiki/Geodesy>, and satellite navigation <https://en.m.wikipedia.org/wiki/Satellite_navigation> including GPS <https://en.m.wikipedia.org/wiki/GPS>. WGS84 (elipsoid) and EGM96 (geoid) are two different models, with different applications. The latest major revision of WGS 84 is also referred to as "Earth Gravitational Model 1996" (EGM96), first published in 1996, with revisions as recent as 2004. This model has the same reference ellipsoid as WGS 84, but has a higher-fidelity geoid (roughly 100 km resolution versus 200 km for the original WGS 84). When you see a height in a map, it is usually a height over the geoid (orthometric height), but when you get one from a GPS device, it is usually a height over the elipsoid. There are online tools to transform between them as needed, using what it is called geoid undulation. E.g. geoid-height-calculator The tl;dr is that you need to reference which model your peak height is measured against. EGM96 is preferred (I'm assuming) because it has higher definition and more refined model. Donal On Fri, 29 Nov 2019, 19:00 moltonel 3x Combo, <molto...@gmail.com> wrote: > Hi, > > I've just fixed Lugnaquilla's "ele" tag to use the EGM96 system, as > opposed to the WGS84 one: > https://www.openstreetmap.org/changeset/77737107 > https://wiki.openstreetmap.org/wiki/Key:ele?uselang=en > > That one was reported by an OSM note, but I wouldn't be surprised if > most of the natural=peak have the same issue. I think it's possible to > find those using an overpass query that would return all natural=peak > where ele == ele::egs84, but I couldn't figure that query out straight > away and there may be a lot of stuff to carefully fix, so I'm turning > to the mailing list. > > Might get a solution tomorrow during the Kilkenny meetup, but I > figured I might as well ask here so I don't forget about it. > > > -- > Vincent de Phily > > _______________________________________________ > Talk-ie mailing list > Talk-ie@openstreetmap.org > https://lists.openstreetmap.org/listinfo/talk-ie > _______________________________________________ Talk-ie mailing list Talk-ie@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-ie
