Input
Results
| Operation | Result | ΔObfs/m | ΔRoundtrip/m |
|---|---|---|---|
| WGS → GCJ | (18.58107856, -68.95081874) 18°34′51.8828″ N, 68°57′2.9475″ W | 3.4357561393020546e+3 | 1.429846021040335e+1 |
| WGS → BD | (18.58724875, -68.94425555) 18°35′14.0955″ N, 68°56′39.32″ W | 4.141284073494332e+3 | 1.4327206635107864e+1 |
| GCJ → WGS | (18.58558144, -69.01584126) 18°35′8.0932″ N, 69°0′57.0285″ W | 3.435710989010595e+3 | 1.650026569548999e+1 |
| BD → WGS | (18.57978225, -69.02228773) 18°34′47.2161″ N, 69°1′20.2358″ W | 4.124990849520378e+3 | 1.645937886377839e+1 |
| GCJ →cai WGS | (18.58567900, -69.01572402) 18°35′8.4444″ N, 69°0′56.6065″ W | 3.424196494491009e+3 | 2.0494168773356125e-4 |
| BD →cai WGS | (18.57987910, -69.02217106) 18°34′47.5648″ N, 69°1′19.8158″ W | 4.111730426646035e+3 | 5.49432220790027e-4 |
| GCJ → BD | (18.58919302, -68.97685103) 18°35′21.0949″ N, 68°58′36.6637″ W | 9.440936601013169e+2 | 2.2493389559636007e-2 |
| BD → GCJ | (18.57751313, -68.98979989) 18°34′39.0473″ N, 68°59′23.2796″ W | 9.398799189789529e+2 | 2.0719898509938498e-2 |
| BD →cai GCJ | (18.57751295, -68.98979987) 18°34′39.0466″ N, 68°59′23.2795″ W | 9.398921081514251e+2 | 1.7800598931148155e-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.