Human-Intelligible Positioning

Vishy Venugopalan & Robert Miller

Motivation
This project is exploring absolute address schemes for locations in the world (such as buildings, street corners, and park benches) that are easy for humans to understand, remember, locate, compare, and communicate to others.

Commonly, people identify locations in a city by giving a street or block address, such as "77 Massachusetts Avenue, Cambridge, MA 02139 USA," or "7-8-4 Roppongi, Minato-ku, Tokyo, Japan."

Today, however, the increasing availability of Global Positioning System (GPS) receivers raises the possibility of using absolute coordinates for everyday location and navigation. Absolute coordinates have some powerful advantages. A location can be found, and distances and directions can be computed, without reference to a map. Fine-grained locations can be described by coordinates even if they lack a distinct street address --- for example, buildings in a complex (such as a shopping mall, campus, or office park), locations in a public space or park, and particular features of a building (such as entrances, loading docks, or parking lots). Finally, unlike street addresses, absolute coordinates are unambiguous. There are many streets in the Boston area named "Main Street" or "Broadway", which can easily lead a visitor astray. No such confusion is possible with absolute coordinates.

Current GPS receivers use latitude and longitude to express absolute positions. Describing a position to an accuracy of a few meters requires 5 decimal places, such as "N42.35933 W71.09400". Unfortunately, this code is not ideal for a human user to remember and communicate to others. Part of the problem is its length (14-16 digits) and self-similarity (digits can be easily confused or transposed). Worse, latitude/longitude coordinates bear no relationship to the human world --- unlike street addresses, in which the hierarchy of country, province/state, city, neighborhood, and street correspond to social and geographical features that are easier to remember and understand. Latitude and longitude must be expressed absolutely, even if the destination is only a few blocks away --- unlike street addresses, which allow users to take advantage of spatial locality. For these reasons, it seems unlikely that people will rush to use latitude and longitude for everyday addressing.

Approach
Human-Intelligible Positioning (HIP) is a new addressing scheme for GPS that overcomes these flaws. A HIP address has three parts: A hierarchical name lookup service resolves a name such as US/Massachusetts/Cambridge into a coordinate system, representing a region on the earth's surface. A coordinate system has a latitude, longitude, and scale factor, which are used to resolve the two-dimensional offset of an address into a point on the earth. To test HIP addresses in the context of an application, we developed a user interface for location and navigation on a Java-enabled cell phone (the Motorola i88s phone, which includes a GPS receiver as well as a Java API for obtaining GPS locations). The application supports three important tasks for mobile users: (1) obtaining the user's current location as a HIP address; (2) obtaining directions from one address to another; and (3) displaying a map of the area around an address.
Acknowledgements
This work was supported in part by NTT.
References:

[1] Vishwanath Venugopalan. Human-Intelligible Positioning. MEng thesis, Massachusetts Institute of Technology, January 2004.