Input
Results
| Operation | Result | ΔObfs/m | ΔRoundtrip/m |
|---|---|---|---|
| WGS → GCJ | (29.15268219, -13.41415786) 29°9′9.6559″ N, 13°24′50.9683″ W | 1.7832128750239576e+3 | 2.5259663225773386e+0 |
| WGS → BD | (29.15866670, -13.40767362) 29°9′31.2001″ N, 13°24′27.625″ W | 2.3418119178273014e+3 | 2.53361842880433e+0 |
| GCJ → WGS | (29.16193781, -13.44932214) 29°9′42.9761″ N, 13°26′57.5597″ W | 1.7831392129511232e+3 | 4.581655200100447e+0 |
| BD → WGS | (29.15598057, -13.45574715) 29°9′21.5301″ N, 13°27′20.6897″ W | 2.3359087701415924e+3 | 5.28307445698314e+0 |
| GCJ →cai WGS | (29.16190534, -13.44935130) 29°9′42.8592″ N, 13°26′57.6647″ W | 1.78481398699108e+3 | 1.4925539760508572e-5 |
| BD →cai WGS | (29.15594363, -13.45578146) 29°9′21.3971″ N, 13°27′20.8133″ W | 2.339497264123558e+3 | 2.0397662834415194e-5 |
| GCJ → BD | (29.16327086, -13.42531824) 29°9′47.7751″ N, 13°25′31.1457″ W | 9.100341224271167e+2 | 1.743311131686962e-2 |
| BD → GCJ | (29.15135813, -13.43815660) 29°9′4.8893″ N, 13°26′17.3638″ W | 9.089874895471337e+2 | 6.627408874983022e-3 |
| BD →cai GCJ | (29.15135807, -13.43815661) 29°9′4.8891″ N, 13°26′17.3638″ W | 9.089932950686785e+2 | 6.066190483667139e-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.