Recently I saw that Amap (AutoNavi) launched a "Location Passcode": six digits that take you directly to any location. As a GIS professional, my first reaction was almost a reflex—isn't this just a domestic version of Plus Code / Open Location Code? After trying it out myself, I found it's not quite the same thing. Today, I'd like to discuss this new feature of Amap.

Feature Introduction

The Location Passcode is simple to use. Open the Amap app with an internet connection, tap the "+" icon in the upper right corner of the home screen to enter the feature page, and select Location Passcode.

Pick a point on the map, and the system generates a set of six digits. The recipient enters these six digits into the search box of the Amap app, and it will drop a pin on that exact location. This feature is mainly used in places without specific names, such as highway emergency lanes, riversides, and mountainous areas. Previously, you would locate yourself and share your real-time location via WeChat, and then the friend would use Amap for navigation. Now, you can just tell them a six-digit code. Currently, the default validity period is one hour.

Underlying Principle

Doesn't this look similar to the Plus Code I shared before? I skimmed the official description and suspect it works more like the following pipeline:

  1. The user selects a point, and the client obtains the latitude and longitude.
  2. The server allocates a set of six digits from a short-code pool and writes the mapping "passcode → coordinates + reverse geocoding description + expiration time" into the server-side store.
  3. When the recipient enters the passcode, Amap queries the database to restore the location, then opens navigation.

Why do I think so? Because there are only one million combinations for six pure digits. If you assume a permanent, nationwide coverage down to the level of intersections or buildings, the encoding space is far from sufficient. The passcode expires and relies on Amap's cloud resolution, so I'm more inclined to believe it's this kind of scheme rather than the deterministic grid encoding of Plus Code.

P.S. The above principle is purely speculation; corrections are welcome.

Difference from Plus Code

The official name of Plus Code is Open Location Code (OLC), open-sourced by Google under the Apache License. It encodes WGS84 latitude and longitude into a readable string (using a set of 20 characters, with a + separator). Essentially, it's a global hierarchical grid that can achieve meter-level precision. The code for the same location is deterministic, and encoding/decoding can be done locally without relying on any vendor's server lookup.

In areas lacking house numbers or POI names, it's like giving the Earth a "short address." I previously created an online conversion tool in Online Tool to Convert Coordinates to Plus Code, using Google's open-location-code implementation.

You can search Plus Codes directly in products like Google Maps, and developers can store them in databases as stable location IDs. When compared with Amap's "Location Passcode," the key difference lies in whether it's a permanent address code or a temporary sharing code. Plus Code uses alphanumeric characters with a +, is globally usable, works offline, and can be openly integrated. The Location Passcode is six pure digits, relies on the Amap app and cloud, and expires after about one hour by default—making it more suitable for verbal relay and temporary meetups.

Conclusion

Initially, I thought Amap was building a "China version of Plus Code," but I later realized I was overthinking it from a technical perspective. Given the official use cases, Amap's approach is clearly more suitable. Comparing G98V+384 to 006783, the latter is definitely easier to remember and offers a better user experience.