|latitude: 24, longitude: 102|
|Browse Yunnan map 24° 0′ 0″ N, 102° 0′ 0″ E|
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Yunnan is a province in China at latitude 24° 0′ 0″ North, longitude 102° 0′ 0″ East. Compared with other Chinese provinces, quite a bit of data has been entered for Yunnan.
There is a good visualization of the OSM work in Yunnan (and actually overall China), with a transparent OSM map with either Chinese or English labels over Google and other terrain visualizations, at YunnanExplorer. This map is updated daily to reflect changes in OSM data.
Many roads in Kunming, the capital of Yunnan, have been either tracklogged or edited from Yahoo imagery, which covers the Kunming urban area at a reasonably high resolution. However, the imagery is well out of date, something that particularly affects the outer suburbs, which have been growing rapidly. I believe that most roads in the center have been entered, many of which have been name-tagged.
While for central Kunming most traffic-bearing roads have been entered, this does not apply to residential districts (xiaoqu), which often have a maze of alleys and road, some of which have names, others not. Roads that are inside residential compounds are tagged as residential. Often they have gates or other access restrictions. These roads generally have no separate names. Buildings have names within a residential compound.
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Apparently there have been several import attempts, resulting in many different tagging schemes. The US data for Yunnan is hopelessly wrong, it would have been better not to import it.
The old town of Dali has been almost completely mapped. Streets within the old city walls should be complete with names, temples, markets, some shops have been added.
A number of roads have been added, mostly major ones, but also some minor roads and tracks. Overall the road network in Yunnan is not very dense and the official numbering scheme does not always reflect the real importance. The convention used here is:
- Expressways tagged as motorways
- Key connecting roads, not expressways, tagged as trunk roads
- Other roads connecting county towns tagged as primary roads
- Roads connecting county towns with townships tagged as secondary roads
- Roads to remote townships, or connecting townships with each other, tagged as tertiary roads
- Dirt roads, rarely used, tagged as tracks.
- Caravan trails tagged as bridleways.
The Dali-Kunming, Kunming-Chengdu, Kunming-Nanning, Dali-Lijiang railways have been mapped within Yunnan. Others, such as to Guiyang or Chongqing not. The railway to Hekou is not in passenger operation anymore, but has been imported from VMAP0 for historical reasons. The VMAP0 data seems to be accurate to within a few hundred meters which is useful for spotting and correcting the line in the field. Within KM some railways have been mapped from Yahoo.
Lakes have been imported from NASA SWBD (water bodies mask) data. This data is quite correct, even though sometimes rice fields have been identified as lakes. Rivers have been generated from SRTM data (using the GRASS flowmodels). Again this data is often quite good, but the generated rivers are not always connected. Major rivers, such as the Jinsha (upper reaches of the Yangzi), Mekong, Red River have been fixed with Yahoo images. Some of the rivers have been tagged with names, but this is only possible with the major rivers where names are known. This requires all more editing with satellite imagery.