Input
Results
| Operation | Result | ΔObfs/m | ΔRoundtrip/m |
|---|---|---|---|
| WGS → GCJ | (19.73056628, -71.00068281) 19°43′50.0386″ N, 71°0′2.4581″ W | 3.430836290682178e+3 | 1.483392330642997e+1 |
| WGS → BD | (19.73666866, -70.99416420) 19°44′12.0072″ N, 70°59′38.9911″ W | 4.1160186176250045e+3 | 1.4856831677703047e+1 |
| GCJ → WGS | (19.73609372, -71.06597719) 19°44′9.9374″ N, 71°3′57.5179″ W | 3.430777404968646e+3 | 1.0567023943662518e+1 |
| BD → WGS | (19.73031463, -71.07238913) 19°43′49.1327″ N, 71°4′20.6009″ W | 4.101885738057681e+3 | 9.336617251489407e+0 |
| GCJ →cai WGS | (19.73616292, -71.06590814) 19°44′10.1865″ N, 71°3′57.2693″ W | 3.4242781213880526e+3 | 2.0711420178500187e-5 |
| BD →cai WGS | (19.73037612, -71.07232852) 19°43′49.354″ N, 71°4′20.3827″ W | 4.095008647170098e+3 | 2.3643617830623535e-5 |
| GCJ → BD | (19.73913160, -71.02689222) 19°44′20.8738″ N, 71°1′36.812″ W | 9.328276882463499e+2 | 3.352333776362424e-2 |
| BD → GCJ | (19.72753982, -71.03975895) 19°43′39.1434″ N, 71°2′23.1322″ W | 9.313005312034603e+2 | 1.8275995134850915e-2 |
| BD →cai GCJ | (19.72753985, -71.03975912) 19°43′39.1435″ N, 71°2′23.1328″ W | 9.313104588524027e+2 | 4.417578862393726e-6 |
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.