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You haven't seen pain until you've had to deal with crappy embedded systems that output "decimal DMS" data - i.e. ones in which 126.5904 means 126° 59' 04, rath

You haven't seen pain until you've had to deal with crappy embedded systems that output "decimal DMS" data - i.e. ones in which 126.5904 means 126° 59' 04, rather than 126° 35' 25.44" as you might expect. Plus, the crappy documentation doesn't bother to tell you what coordinate system they're using so you get to guess! I wish I'd known about the little calculator they have on this site - which guesses the coordinate system in use - back when I was doing that project. Would have saved me a lot of headaches. The next pain point has got to be China's insane "GCJ-02" obfuscated coordinate system, as alluded to and linked on this site. I've had a lot of trouble getting basically anything GPS-related to spit out meaningful things while in that country (more accurately, matching basically anything up with maps while there). While it has been reverse-engineered, you always get to wonder whether the authorities are going to come after you for having GPS data that's too accurate... Coordinate systems are hard. GIS stuff is hard. I'm glad this website exists. Even if it's hard for people to identify the problem, this site at least makes one aware of the problems in the first place.

jiggawatts 6y ago
Ostensibly, GCJ-02 is for national security. Given that all of China's potential enemies have detailed satellite maps of the region and aren't in the slightest bit inconvenienced in their targeting accuracy because of GCJ-02, that's obviously false. Clearly, GCJ-02 is just simple, ordinary corruption, the type endemic to China. Someone convinced some politician with a bag of money to keep a legally mandated monopoly on mapping, locking out foreign competitors. PS: Japan does similar things, where for example Google Maps refuses to "download" maps of Japan because by law they are not allowed to make their own maps of Japan and must license the data from a local provider. That local provider does not allow offline use. The world of mapping is nuts.
- maxerickson 6y ago
  Is it illegal for Google to make maps of Japan or just not a good investment? (that the licensed data they use has some restrictions is clear enough)
  - jiggawatts 6y ago
    Seems to have been more of a licensing contract things, apparently it got fixed right after my most recent trip to Japan: https://www.reddit.com/r/japan/comments/dt4pe7/google_maps_adds_support_for_offline_maps_in/ https://www.reddit.com/r/japan/comments/dt4pe7/google_maps_a...
- garaetjjte 6y ago
  South Korea is weird too, Google Maps only have pre-rendered bitmaps from local provider.
  - yongjik 6y ago
    Yes, South Korea has this braindead law prohibiting "export" of map data - so in order to have a map service the map data server must be physically located inside Korea.
- segfaultbuserr 6y ago
  > Given that all of China's potential enemies have detailed satellite maps of the region and aren't in the slightest bit inconvenienced in their targeting accuracy because of GCJ-02, that's obviously false. What makes the situation even funnier is that Google-Earth-style satellite images were (and still are?) not regulated as maps, and they're free to be published with unobstructed WGS-84 coordinates. Only the maps are regulated to use GCJ-02. If you use a standard GPS receiver, your location will be perfectly normal in satellite view, until you switch the display to map view. Claiming it can protect "national security" is just fooling oneself.

jiggawatts 6y ago

Ostensibly, GCJ-02 is for national security. Given that all of China's potential enemies have detailed satellite maps of the region and aren't in the slightest bit inconvenienced in their targeting accuracy because of GCJ-02, that's obviously false. Clearly, GCJ-02 is just simple, ordinary corruption, the type endemic to China. Someone convinced some politician with a bag of money to keep a legally mandated monopoly on mapping, locking out foreign competitors. PS: Japan does similar things, where for example Google Maps refuses to "download" maps of Japan because by law they are not allowed to make their own maps of Japan and must license the data from a local provider. That local provider does not allow offline use. The world of mapping is nuts.

maxerickson 6y ago
Is it illegal for Google to make maps of Japan or just not a good investment? (that the licensed data they use has some restrictions is clear enough)
- jiggawatts 6y ago
  Seems to have been more of a licensing contract things, apparently it got fixed right after my most recent trip to Japan: https://www.reddit.com/r/japan/comments/dt4pe7/google_maps_adds_support_for_offline_maps_in/ https://www.reddit.com/r/japan/comments/dt4pe7/google_maps_a...
garaetjjte 6y ago
South Korea is weird too, Google Maps only have pre-rendered bitmaps from local provider.
- yongjik 6y ago
  Yes, South Korea has this braindead law prohibiting "export" of map data - so in order to have a map service the map data server must be physically located inside Korea.
segfaultbuserr 6y ago
> Given that all of China's potential enemies have detailed satellite maps of the region and aren't in the slightest bit inconvenienced in their targeting accuracy because of GCJ-02, that's obviously false. What makes the situation even funnier is that Google-Earth-style satellite images were (and still are?) not regulated as maps, and they're free to be published with unobstructed WGS-84 coordinates. Only the maps are regulated to use GCJ-02. If you use a standard GPS receiver, your location will be perfectly normal in satellite view, until you switch the display to map view. Claiming it can protect "national security" is just fooling oneself.