Input
Results
| Operation | Result | ΔObfs/m | ΔRoundtrip/m |
|---|---|---|---|
| WGS → GCJ | (34.99909265, 105.00328624) 34°59′56.7335″ N, 105°0′11.8305″ E | 3.158769128712098e+2 | 1.799748927642437e+0 |
| WGS → BD | (35.00539769, 105.00966683) 35°0′19.4317″ N, 105°0′34.8006″ E | 1.0655886340270229e+3 | 1.7972571843116967e+0 |
| GCJ → WGS | (35.00090735, 104.99671376) 35°0′3.2665″ N, 104°59′48.1695″ E | 3.158737675820679e+2 | 1.7773169089814569e+0 |
| BD → WGS | (34.99464105, 104.99035737) 34°59′40.7078″ N, 104°59′25.2865″ E | 1.0613910199779505e+3 | 1.7119439105429257e+0 |
| GCJ →cai WGS | (35.00091622, 104.99672986) 35°0′3.2984″ N, 104°59′48.2275″ E | 3.148020053077608e+2 | 5.040050938607185e-5 |
| BD →cai WGS | (34.99464910, 104.99037324) 34°59′40.7368″ N, 104°59′25.3437″ E | 1.0596921860574007e+3 | 5.469393782944462e-5 |
| GCJ → BD | (35.00630952, 105.00637857) 35°0′22.7143″ N, 105°0′22.9629″ E | 9.10908211191517e+2 | 1.5012008791869286e-2 |
| BD → GCJ | (34.99370732, 104.99361166) 34°59′37.3464″ N, 104°59′37.002″ E | 9.100644684921092e+2 | 7.586089785263092e-2 |
| BD →cai GCJ | (34.99370664, 104.99361164) 34°59′37.3439″ N, 104°59′37.0019″ E | 9.101236269417449e+2 | 5.009953276388609e-5 |
Permalink to this result. Toggle sections: Notes, FAQ, footer.
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.
