Input
Results
| Operation | Result | ΔObfs/m | ΔRoundtrip/m |
|---|---|---|---|
| WGS → GCJ | (51.89773685, -10.32885822) 51°53′51.8527″ N, 10°19′43.8896″ W | 1.546941936078122e+3 | 6.270688842107038e+0 |
| WGS → BD | (51.90371146, -10.32249792) 51°54′13.3613″ N, 10°19′20.9925″ W | 1.9707077482234117e+3 | 6.3044341062852665e+0 |
| GCJ → WGS | (51.90392315, -10.37282178) 51°54′14.1233″ N, 10°22′22.1584″ W | 1.5468406942070917e+3 | 4.982933256816454e+0 |
| BD → WGS | (51.89791485, -10.37936042) 51°53′52.4935″ N, 10°22′45.6975″ W | 1.9835151918337872e+3 | 4.321520226583346e+0 |
| GCJ →cai WGS | (51.90395668, -10.37277378) 51°54′14.244″ N, 10°22′21.9856″ W | 1.5444646947944104e+3 | 1.662080319367408e-5 |
| BD →cai WGS | (51.89794433, -10.37931903) 51°53′52.5996″ N, 10°22′45.5485″ W | 1.9801790253891977e+3 | 1.0049406243650717e-4 |
| GCJ → BD | (51.90683051, -10.34433298) 51°54′24.5898″ N, 10°20′39.5987″ W | 8.027945241160154e+2 | 4.131817741889806e-3 |
| BD → GCJ | (51.89481311, -10.35739732) 51°53′41.3272″ N, 10°21′26.6304″ W | 8.062634167127904e+2 | 3.162657092556528e-2 |
| BD →cai GCJ | (51.89481300, -10.35739775) 51°53′41.3268″ N, 10°21′26.6319″ W | 8.062893815648157e+2 | 2.3625282503399558e-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.