Talk:Key:depth

Feet and inches

There's currently a proposal for ele=* to accept values in feet and inches as long as the unit is specified, a change from the current definition that only allows values in meters. Since 2014, depth=* has also been specified to be measured in meters only, probably for consistency with ele=*, the only other key that is defined this way. However, about a third (403/1,294) of occurrences in the U.S. are explicitly expressed in feet and inches, with possibly more implicit occurrences, demonstrating a strong demand for an option to express depths this way. Compared to elevations, depths are often tagged at a much smaller scale, such as on swimming pools, where there's a substantial difference between 3 ¹⁄₂ feet (1.1 m) and 3.5 metres (11 ft) and a greater need for precision. Considering that this key has never been formally approved and has less software support, would it be reasonable to simply modify the definition here, or should it be included in the same proposal as ele=*? – Minh Nguyễn ^💬 02:13, 3 December 2021 (UTC)

You should ignore this for the same reason as Proposed_features/ele_with_units#Examples. There will be issues for different (tidal) datum, without even a clear reference as EGM96 geoid in ele=*; and definition of Lowest Astronomical Tide, compared to the usual Mean High Water Springs handled in natural=coastline. ---- Kovposch (talk) 03:54, 3 December 2021 (UTC)

From Water_Depth#Chart_datum,  Chart_datum#Satellite_navigation mentions the use of GRS80 ellipsoid, unlike WGS84. ---- Kovposch (talk) 04:03, 3 December 2021 (UTC)

as said in the article "The GRS 80 reference system was originally used by the World Geodetic System 1984 (WGS 84). The reference ellipsoid of WGS 84 now differs slightly due to later refinements.". In practice, they are almost the same: [WGS84+GRS80 / Mercator https://epsg.io/42310]. --Nospam2005 (talk) 22:59, 28 November 2022 (UTC)