Input
Results
| Operation | Result | ΔObfs/m | ΔRoundtrip/m |
|---|---|---|---|
| WGS → GCJ | (39.47959097, -0.36387852) 39°28′46.5275″ N, 0°21′49.9627″ W | 1.4152959831694636e+3 | 2.2319226441225535e+0 |
| WGS → BD | (39.48558947, -0.35749452) 39°29′8.1221″ N, 0°21′26.9803″ W | 2.0126810975761741e+3 | 2.236162110426886e+0 |
| GCJ → WGS | (39.48276903, -0.39660148) 39°28′57.9685″ N, 0°23′47.7653″ W | 1.4152641526132597e+3 | 1.068270340088286e+0 |
| BD → WGS | (39.47678079, -0.40308023) 39°28′36.4108″ N, 0°24′11.0888″ W | 2.0204124276187358e+3 | 9.131789813934629e-1 |
| GCJ →cai WGS | (39.48277831, -0.39660474) 39°28′58.0019″ N, 0°23′47.7771″ W | 1.4156708433703366e+3 | 3.171383360262214e-4 |
| BD →cai WGS | (39.47678572, -0.40308873) 39°28′36.4286″ N, 0°24′11.1194″ W | 2.0209879919848308e+3 | 5.262489369054614e-3 |
| GCJ → BD | (39.48718068, -0.37379794) 39°29′13.8504″ N, 0°22′25.6726″ W | 8.6652700691973e+2 | 2.6924268793819428e-2 |
| BD → GCJ | (39.47518519, -0.38671993) 39°28′30.6667″ N, 0°23′12.1917″ W | 8.681339229556509e+2 | 1.0537328833983676e-2 |
| BD →cai GCJ | (39.47518519, -0.38671981) 39°28′30.6667″ N, 0°23′12.1913″ W | 8.68127525183983e+2 | 6.432917461408055e-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.