Input
Results
| Operation | Result | ΔObfs/m | ΔRoundtrip/m |
|---|---|---|---|
| WGS → GCJ | (13.66551164, -88.16339227) 13°39′55.8419″ N, 88°9′48.2122″ W | 3.957448504496585e+3 | 1.1412198083276209e+1 |
| WGS → BD | (13.67159922, -88.15686477) 13°40′17.7572″ N, 88°9′24.7132″ W | 4.692686805282245e+3 | 1.1386696685261116e+1 |
| GCJ → WGS | (13.66782836, -88.23660773) 13°40′4.1821″ N, 88°14′11.7878″ W | 3.9574290704578884e+3 | 7.25520188262253e+0 |
| BD → WGS | (13.66206714, -88.24309820) 13°39′43.4417″ N, 88°14′35.1535″ W | 4.684703738502154e+3 | 6.055950035387142e+0 |
| GCJ →cai WGS | (13.66778855, -88.23666102) 13°40′4.0388″ N, 88°14′11.9797″ W | 3.9630425383689217e+3 | 7.004314162544852e-6 |
| BD →cai WGS | (13.66203485, -88.24314360) 13°39′43.3255″ N, 88°14′35.317″ W | 4.689972730636503e+3 | 5.993779779928598e-5 |
| GCJ → BD | (13.67240343, -88.19352830) 13°40′20.6523″ N, 88°11′36.7019″ W | 9.462426525958981e+2 | 2.298781573025669e-2 |
| BD → GCJ | (13.66092204, -88.20647813) 13°39′39.3193″ N, 88°12′23.3213″ W | 9.478572054588483e+2 | 1.8963405800003646e-2 |
| BD →cai GCJ | (13.66092212, -88.20647797) 13°39′39.3196″ N, 88°12′23.3207″ W | 9.478388598465956e+2 | 8.05932872834507e-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.