Input
Results
| Operation | Result | ΔObfs/m | ΔRoundtrip/m |
|---|---|---|---|
| WGS → GCJ | (18.36441521, -71.18399211) 18°21′51.8948″ N, 71°11′2.3716″ W | 3.45764210516159e+3 | 8.327972659095177e+0 |
| WGS → BD | (18.37035028, -71.17751359) 18°22′13.261″ N, 71°10′39.0489″ W | 4.152369659923599e+3 | 8.302508196393795e+0 |
| GCJ → WGS | (18.36892479, -71.24934789) 18°22′8.1292″ N, 71°14′57.6524″ W | 3.457597166360848e+3 | 3.598108213052692e+0 |
| BD → WGS | (18.36270414, -71.25590977) 18°21′45.7349″ N, 71°15′21.2752″ W | 4.1644584650242605e+3 | 2.4407163418924154e+0 |
| GCJ →cai WGS | (18.36890549, -71.24937527) 18°22′8.0598″ N, 71°14′57.751″ W | 3.4603244675542887e+3 | 4.4957055447688836e-7 |
| BD →cai WGS | (18.36269272, -71.25592950) 18°21′45.6938″ N, 71°15′21.3462″ W | 4.166663220452689e+3 | 4.210187494775994e-6 |
| GCJ → BD | (18.37288212, -71.21012236) 18°22′22.3756″ N, 71°12′36.4405″ W | 9.770235297959644e+2 | 2.425311575593319e-2 |
| BD → GCJ | (18.36045909, -71.22322365) 18°21′37.6527″ N, 71°13′23.6051″ W | 9.773943946608834e+2 | 2.6287821479951914e-2 |
| BD →cai GCJ | (18.36045925, -71.22322383) 18°21′37.6533″ N, 71°13′23.6058″ W | 9.773962477593665e+2 | 4.3469649421054876e-5 |
Permalink to this result. Toggle sections: Notes, FAQ, footer. And print.
Notes
- Caijun’s iterative method is included for precise decoding.
It's most useful for bored folks whose GPS data is pretty accurate
and GCJ-02 obfuscation not tainted by the original
LCPRNG.
If you are doing Wikipedia or any kind of archival work, use it to avoid introducing extra error.
- BD is defined in terms of GCJ, hence the last three functions.
- This demo omits the “in China” sanity check. Data regarding
Baidu’s behavior with overseas maps is needed for further
decisions. Observations:
- Unlike Google Maps, Baidu's map in Hong Kong is fully subject to BD-09 ∘ GCJ-02 chained distortions.
- Coordinates in Russia, outside of the sanity check rectangle, uses WGS-84 or and/or friends.
- TODO: check along the boundary.
FAQ
- What is this all about?
- The PRC government requires all local map services to use an obfuscated, deviation-orienated coordinate system. Click on the “restriction” link to read the full Wikipedia article.
- Why should I care?
- With half a kilometer of deviation, GCJ-02 and friends fucks up your Ingress games, causes crazy errors in elevation profiles along cycle routes, and cheerfully leads you into roadside ditches plus a bone fracture.
- Why doesn’t Google/Bing correct its Chinese data served to global users?
- I don’t know. Perhaps they are afraid of getting fined or further kicked out of China. Maybe try OpenStreetMap next time?
- Why are you writing another implementation?
- Because I got bored.
- How does Caijun’s iterative method work?
- Cai has explained the method in full in his R implementation. Go read it, or read Wikipedia.