Edi & change status, I would say. Seems a pretty clear case, just maybe not something many mappers or users are very concerned with. But that's not a problem as long as there is a clear definition, solid data and a steady group of mappers/users. I would say, just do it and document it.
Op zo 23 sep. 2018 om 03:05 schreef Joseph Eisenberg < joseph.eisenb...@gmail.com>: > For most peaks, it's only necessary to know the elevation of the > nearby saddles and peaks to find the prominence. For example, walk to > the top of the hill and record the elevation. Look around and find any > taller nearby peaks. If there is only 1 taller hill, walk down the > ridge line to the lowest point between the first hill and the taller > hill, then record the saddle elevation. Prominence is then elevation > of the first peak minus the elevation of the saddle. > > It's more difficult for very prominent peaks, where the "key col" or > lowest saddle may be 1000's of kilometers away, but all of these peaks > already have prominence calculated and listed on Wikipedia: > https://en.wikipedia.org/wiki/List_of_peaks_by_prominence, > https://en.wikipedia.org/wiki/List_of_islands_by_highest_point, > https://en.wikipedia.org/wiki/List_of_Ultras_of_Africa > > I just remembered that there was an abandoned proposal for this tag. > How do I revive the proposal? Just start editing the page, > https://wiki.openstreetmap.org/wiki/Proposed_features/key:prominence > Or make a new page? > > Joseph > > On 9/23/18, Warin <61sundow...@gmail.com> wrote: > > On 23/09/18 10:00, Joseph Eisenberg wrote: > >> I've been tagging peaks (natural=peak) with the key > >> prominence=<topographic prominence in meters> > >> > >> Prominence is a natural feature with a use similar to elevation. When > >> I see ele=*, I know how high the top of the peak is, but not how tall > >> the peak is compared to the surrounding land. For example, a hill in > >> my valley may have ele=2000m, but it isn't a mountain: it's a 300m > >> hill that rises out of surrounding land at 1700m. > >> > >> Prominence is calculated by subtracting the elevation of the lowest > >> saddle (or "col") from the elevation of the peak: > >> > >> https://en.wikipedia.org/wiki/Topographic_prominence > >> > >> "The prominence of a peak is the minimum height necessary to descend > >> to get from the summit to any higher terrain" or "the height of the > >> peak’s summit above the lowest contour line encircling it but > >> containing no higher summit within it." > >> > >> Both of these definitions are the same for all peaks except for the > >> highest peak on a landmass, eg Mount Everest in Eurasia: in this case > >> use the second definition, which means that the tallest peak on a > >> (super-)continent or island is the same as it's elevation. > >> > >> This started when I became interested in "peak bagging", where hikers > >> and climbers record the peaks they have summited. There are separate > >> categories based on the prominence of a peak. Gunungbagging.com in > >> Indonesia lists elevation, prominence and names for many peaks here in > >> Indonesia, and the site authors gave permission for the data to be > >> added to Openstreetmap. > >> > >> There are other lists of prominent peaks for the rest of the world, > >> but please check if you can use the data based on the license, before > >> adding it to OSM. > >> > >> Elevation and prominence can both be calculated from SRTM data, eg by > >> using Opentopomap tiles and finding the highest contour lines around a > >> peak, and the lowest near a saddle. > >> > >> Prominence and elevation can be calculated by computer with good data, > >> but for my part of the world the SRTM data is not high enough quality > >> to get good results without cross-checking against aerial imagery. > >> Also the calculations are not simple, and are not precise for sharply > >> pointed peaks or deeply carved saddles, therefore I believe it will be > >> useful to include this data directly in tags. > >> > >> I also find that calculation the prominence of peaks has encouraged me > >> to add more ridge lines and saddle points (with elevations), which > >> should make the database more useful in mountainous areas. > >> > >> Do you think I should write up a formal proposal for this tag? > >> > > > > Yes to documenting it. > > > > The evaluation of 'prominence' would be to some local area .. what is the > > size of that area? > > > > ---------------- > > Some will say a formal proposal is 'best'. It is up to you to decide > what is > > 'best'. > > But by all means discuss it here. > > > > > > _______________________________________________ > > Tagging mailing list > > Tagging@openstreetmap.org > > https://lists.openstreetmap.org/listinfo/tagging > > > > _______________________________________________ > Tagging mailing list > Tagging@openstreetmap.org > https://lists.openstreetmap.org/listinfo/tagging > -- Vr gr Peter Elderson
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