Input
Results
| Operation | Result | ΔObfs/m | ΔRoundtrip/m |
|---|---|---|---|
| WGS → GCJ | (44.31854099, 23.96606300) 44°19′6.7476″ N, 23°57′57.8268″ E | 5.82229693028048e+2 | 2.333225031543045e+0 |
| WGS → BD | (44.32454214, 23.97259879) 44°19′28.3517″ N, 23°58′21.3556″ E | 1.2453239467709434e+3 | 2.336751459431504e+0 |
| GCJ → WGS | (44.31993901, 23.95155700) 44°19′11.7804″ N, 23°57′5.6052″ E | 5.822228802828877e+2 | 2.0879499551198686e+0 |
| BD → WGS | (44.31399088, 23.94495272) 44°18′50.3672″ N, 23°56′41.8298″ E | 1.247444035885953e+3 | 1.8498665493627149e+0 |
| GCJ →cai WGS | (44.31995569, 23.95156899) 44°19′11.8405″ N, 23°57′5.6484″ E | 5.815284944726009e+2 | 4.1181438171200225e-6 |
| BD →cai WGS | (44.31400615, 23.94496189) 44°18′50.4221″ N, 23°56′41.8628″ E | 1.2460050058608124e+3 | 1.6332590711370967e-5 |
| GCJ → BD | (44.32521583, 23.96539194) 44°19′30.777″ N, 23°57′55.411″ E | 8.459875483968938e+2 | 4.78125547908791e-2 |
| BD → GCJ | (44.31328010, 23.95219436) 44°18′47.8084″ N, 23°57′7.8997″ E | 8.462951175676995e+2 | 4.823876511704281e-2 |
| BD →cai GCJ | (44.31328037, 23.95219388) 44°18′47.8093″ N, 23°57′7.898″ E | 8.462955672856192e+2 | 1.9921160473181882e-4 |
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.