Input
Results
| Operation | Result | ΔObfs/m | ΔRoundtrip/m |
|---|---|---|---|
| WGS → GCJ | (29.14125858, -13.42893536) 29°8′28.5309″ N, 13°25′44.1673″ W | 1.7849619360561796e+3 | 4.275959352965745e+0 |
| WGS → BD | (29.14720977, -13.42250156) 29°8′49.9552″ N, 13°25′21.0056″ W | 2.3392431473178917e+3 | 4.294062543750064e+0 |
| GCJ → WGS | (29.15048142, -13.46414464) 29°9′1.7331″ N, 13°27′50.9207″ W | 1.7848884372450261e+3 | 6.101034525397185e+0 |
| BD → WGS | (29.14451940, -13.47059691) 29°8′40.2698″ N, 13°28′14.1489″ W | 2.341141187099937e+3 | 6.6375930757790185e+0 |
| GCJ →cai WGS | (29.15043927, -13.46418506) 29°9′1.5814″ N, 13°27′51.0662″ W | 1.7873116754180699e+3 | 3.402655191891828e-5 |
| BD →cai WGS | (29.14447372, -13.47064134) 29°8′40.1054″ N, 13°28′14.3088″ W | 2.345778345160664e+3 | 1.7333463026466785e-4 |
| GCJ → BD | (29.15181976, -13.44011671) 29°9′6.5511″ N, 13°26′24.4202″ W | 9.09284713207099e+2 | 1.3273933160998666e-2 |
| BD → GCJ | (29.13991710, -13.45297947) 29°8′23.7016″ N, 13°27′10.7261″ W | 9.106420829834567e+2 | 1.907759367148549e-2 |
| BD →cai GCJ | (29.13991716, -13.45297928) 29°8′23.7018″ N, 13°27′10.7254″ W | 9.106250440168377e+2 | 5.812908318850973e-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.