I agree with deleting the timezone relations. 2017-03-05 21:30 GMT-03:00 Frederik Ramm <frede...@remote.org>:
> Hi, > > I would like to start a discussion about the mapping of time zones. > > There are currently 80 relations in OSM tagged as boundary=timezone > using between them over 10,000 ways. > > I think that mapping these time zones as geometries has several issues: > > 1. It introduces yet another un-observable object type into OSM. When I > asked about the source of the data, one person quipped "well you can > observe it on a local clock", but the people adding time zone boundaries > don't seem to actually do that - they copy the information from somewhere. > > 2. It is for the most part unnecessary noise; almost all time zone > boundaries run along administrative boundaries, so you could just add a > timezone tag to the administrative entity instead of mapping a whole > separate geometry. > > 3. It complicates editing; anyone touching one of the aforementioned > 10,000 ways (which are for the most part also used by admin boundaries) > will be confronted with the time zone relation and will have to decide > what to do with it. > > 4. It creates very large polygons that may be difficult to edit. > > Here's a list of time zones currently mapped in OSM (with relation ID) > > 3563652 Московское время > 3563678 Екатеринбургское время > 3563726 Красноярское время > 3563727 Омское время > 3563885 Иркутское время > 3563886 Якутское время > 3563937 Владивостокское время > 4297465 Самарское время > 6426325 Cherry County - Chicago TZ part > 6426796 Idaho Denver TZ part > 6426797 Idaho Los Angeles TZ part > 6428675 Alaska - Timezone America/Adak > 6428690 Alaska - Timezone America/Anchorage > 6428730 Alaska - Timezone America/Yakutat > 6428802 Alaska - Timezone America/Juneau > 6428803 Alaska - Timezone America/Sitka > 6428944 Canada - Timezone America/Pangnirtung > 6430296 Malaysia - Kuala Lumpur Timezone > 6430370 Kiribati - Kiritimati timezone > 6430371 Kiribati - Tarava timezone > 6430484 Greenland - timezone America/Danmarkshavn area > 6430503 Greenland - timezone America/Thule area > 6430514 Greenland - timezone America/GodThab area > 6430515 Greenland - timezone America/Scoresbysund area > 6430658 Хандыгское время > 6440860 America/Tijuana Timezone > 6440942 America/Merida Timezone > 6440955 America/Cancun Timezone > 6440975 America/Bahia_Banderas Timezone > 6441066 America/Mazatlan Timezone > 6442501 America/Mexico_City Timezone > 6442514 America/Santa_Isabel Timezone > 6442531 America/Hermosillo Timezone > 6442686 America/Matamoros Timezone > 6442687 America/Ojinaga Timezone > 6442693 America/Chihuahua Timezone > 6442726 America/Monterrey Timezone > 6442820 America/Edmonton Timezone part > 6442821 America/Regina Timezone > 6442822 America/Winnipeg Timezone part > 6445625 America/Eirunepe Timezone > 6445626 America/Manaus Timezone > 6445682 America/Belem Timezone > 6445683 America/Santarem Timezone > 6445860 Asia/Dushanbe Timezone part > 6446092 Arizona - America/Phoenix Timezone > 6446108 America/Atikokan Timezone > 6446109 America/Winnipeg Timezone > 6446170 America/Cambridge_Bay Timezone > 6446189 America/Rankin_Inlet Timezone > 6446190 America/Resolute Timezone > 6451096 Atlantic/Azores Timezone > 6451097 Atlantic/Madeira Timezone > 6451098 Europe/Lisbon Timezone > 6451458 America/Coral_Harbour Timezone > 6451459 America/Iqaluit Timezone > 6483867 Ontario - America/Toronto Timezone > 6483978 America/Creston Timezone > 6483979 America/Dawson_Creek Timezone > 6483980 America/Edmonton Timezone > 6483981 America/Vancouver Timezone > 6485969 Asia/Sakhalin Timezone > 6491030 America/Argentina/Buenos_Aires Timezone > 6491031 America/Argentina/Catamarca Timezone > 6491032 America/Argentina/Rio_Gallegos Timezone > 6491033 America/Argentina/Salta Timezone > 6491034 America/Argentina/Ushuaia Timezone > 6491133 Atlantic/Canary Timezone > 6491134 Europe/Madrid Timezone > 6491494 America/Chicago Timezone > 6496417 America/New_York Timezone > 6496587 America/Indiana/Indianapolis Timezone > 6496665 America/Boise Timezone > 6496694 America/Los_Angeles Timezone > 6498476 America/Menominee Timezone > 6498563 America/Detroit Timezone > 6498592 America/Nipigon Timezone > 6498593 America/Thunder_Bay Timezone > 6594626 Магаданское время > 6594635 Камчатское время > > And here's them in a map: > > http://www.remote.org/frederik/tmp/tz.jpg > > Now when you overlay the administrative boundaries on levels 2 and 4, > only very few lines remain: > > http://www.remote.org/frederik/tmp/tz4.jpg > > And when you go up to admin level 6: > > http://www.remote.org/frederik/tmp/tz6.jpg > > Assuming that these boundaries are actually correct, the only places in > which time zone boundaries don't follow admin boundaries are: > > * In South America, the Western boundary of the Manaus timezone and the > Eastern boundary of the Santarem timezone; > > * In North America, the line between the Hermosillo and Santa Isabel > timezones, the Phoenix timezone, a small part of the boundary between > the Los Angeles and Boise time zones in Malheur county, the Chicago > Timezone in Cherry County, a piece of the Los Angeles timezone in Idaho, > the line between Vancouver and Dawson Creek respectively Creston > timezones, two incursions into the Regina timezone for Edmonton and > Winnipeg, two micro timezones called Nipigon and Thunder Bay, as well as > the Iqaluit and Rankin Inlet timezones far North. (Strangely, around > Alaske the timezone boundary seems to include a few miles of water that > are not included in the admin boundary - a quirk in mapping or a quirk > in time zone definitions?) > > As you can see in the images, these lines make up just a fraction of > time zone boundaries (and it is quite possible that some of these just > shine up because the matching admin6 boundaries haven't yet been mapped). > > I fear that the presence of *some* time zone relations will entice > people to map even more of them, unnecessarily introducing extra > geometries into our database when you could easily build time zone > geometries by either (a) keeping an external database that says "Time > Zone X consists of the following administrative units" and then > collecting the units from OSM, or (b) adding a time zone tag to > adminsitrative entities in OSM - namely, the highest entitiy that still > has the same time zone which will often be a whole country, sometimes an > admin-4 entity and very rarely an admin-6 entity. > > If there are really some time zone bits and pieces that don't follow > admin boudnaries (maybe they're marked with signs on the ground > "caution, wind back your clock all ye who pass here"?) then maybe those > few bits can be mapped as individual objects... but please, don't > inflate OSM with time zone geometries just because "it's easier to > consume that way" (which is the gist from a discussion I had with a time > zone mapper). > > I am worried because with the same reasoning, you could start mapping > things like "states that have signed up to the XYZ treaty", "states in > which XYZ is legal/illegal", or anything else. It's a slippery slope, > and *if* time zones are mapped in OSM at all, I'd rather not have them > mapped as giant geomtries in their own right, but as properties. > > I have recently deleted a few time zone relations in the US and, > grudgingly, reinstated them because I had to accept that a prior > discussion was called for. (Changeset discussion here > https://www.openstreetmap.org/changeset/45644359), and I also requested > the deletion of > http://wiki.openstreetmap.org/wiki/Tag:boundary%3Dtimezone which > prompted verdy_p to write a small novel on the talk page there. > > I find the subject of time zones hugely interesting and seeing the > quirks mapped above has already sent me on a journey reading up on the > details, but I still think that the mapping of time zones as geometries > should be discouraged in OSM. > > What do you think? > > Bye > Frederik > > -- > Frederik Ramm ## eMail frede...@remote.org ## N49°00'09" E008°23'33" > > _______________________________________________ > Tagging mailing list > Tagging@openstreetmap.org > https://lists.openstreetmap.org/listinfo/tagging > -- Wille http://wille.blog.br http://maption.com.br/
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