![]() The only clue is that the timezone ends just east of Caiguna. ![]() ![]() The extent of the Eucla zone is not clear from the tz data. We use a separation along first-level administrative divisons that matches WTE. There is not enough information in the tz data to figure out how Ukraine is divided between them. This country is covered by four tz timezones. There is not enough information in the tz data to figure out how Uzbekistan is divided between them. This country is covered by two tz timezones, Tashkent and Samarkand. The rest of this section discusses the remaining cases, where the definition of the extent of a zone is open to interpretation. That leaves only a few countries with multiple time zones, and again, most of them are straightforward, with timezone matching administrative divisions of the countries: the correspondance is documented in the script we use to build the shapefile (see below). We also discussed the situation of the United States, Canada, Mexico, Russia and China in other pages. The vast majority of the tz timezones are by construction matching a country, so little needs to be said about them: we equate them with the corresponding region in our fips10s data. As a consequence, the shapefiles presented here do not cover seas and oceans. Unfortunately, VMAP0 does not provide geometries for the territorial waters. While the boundaries in international waters are not difficult to construct, the boundaries of territorial waters are a completely different story, and are similar to the boundaries between countries. A captain can change ship's clocks any time after entering a new time zone midnight changes are common.” In international waters, time zone boundaries are meridians 15° apart, except that UTC−12 and UTC+12 are each 7.5° wide and are separated by the 180° meridian (not by the International Date Line, which is for land and territorial waters only). The tz database says: “A ship within the territorial waters of any nation uses that nation's time. This is a snaphsot of the zones (many of the smaller zones are not visible at this scale): The geometries are primarily derived from the fip10s data (itself derived from the VMAP0 data), augmented with data presented in the pages for the maps of the United States, Canada, Mexico, Russia and China. There is a companion map for the TZ timezones used in Antarctica stations. The geometries are either POLYGONs or MULTIPOLYGONs, and there is a single geometry for each TZ timezone. The tz_world_mp shapefile ( zip, sha1) captures the same boundaries. The geometries are all POLYGONs, and a TZ timezone will sometimes have multiple polygons. The tz_world shapefile ( zip, sha1) captures the boundaries of the TZ timezones across the world. A shapefile of the TZ timezones of the world tz_world, an /tz map A shapefile of the TZ timezones of the world This map is no longer maintained.
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