Input
Results
| Operation | Result | ΔObfs/m | ΔRoundtrip/m |
|---|---|---|---|
| WGS → GCJ | (70.97693467, 25.98140167) 70°58′36.9648″ N, 25°58′53.046″ E | 4.456749384784153e+2 | 3.5158615541235094e+0 |
| WGS → BD | (70.98285994, 25.98811512) 70°58′58.2958″ N, 25°59′17.2144″ E | 6.660490803828187e+2 | 3.5243611662618965e+0 |
| GCJ → WGS | (70.98246533, 25.96359833) 70°58′56.8752″ N, 25°57′48.954″ E | 4.4564224663291594e+2 | 3.244853958592433e+0 |
| BD → WGS | (70.97653667, 25.95698293) 70°58′35.532″ N, 25°57′25.1385″ E | 6.6330936395726e+2 | 2.9659911452111984e+0 |
| GCJ →cai WGS | (70.98248785, 25.96365435) 70°58′56.9563″ N, 25°57′49.1557″ E | 4.459127509726927e+2 | 1.2913172814177517e-4 |
| BD →cai WGS | (70.97655711, 25.95703497) 70°58′35.6056″ N, 25°57′25.3259″ E | 6.605056275435243e+2 | 3.2539441491909887e-4 |
| GCJ → BD | (70.98562831, 25.97919684) 70°59′8.2619″ N, 25°58′45.1086″ E | 7.024387422682233e+2 | 4.039344453372476e-2 |
| BD → GCJ | (70.97375181, 25.96583954) 70°58′25.5065″ N, 25°57′57.0223″ E | 7.040862408748181e+2 | 6.206962258551984e-2 |
| BD →cai GCJ | (70.97375141, 25.96584076) 70°58′25.5051″ N, 25°57′57.0267″ E | 7.041119996121561e+2 | 4.7461065364497965e-4 |
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.