Essential principles underpinning services and applications

Navigation

There are relatively few applications for which location or position is the core purpose. Navigation is the notable example in which the purpose is to find a place or navigate a route to a place. Before the advent of modern technology ocean navigation was a huge problem facing mariners at sea. With the help of a sextant measuring the inclination of the Sun above the horizon at midday allows one’s latitude to be estimated. However, determining longitude is far more difficult. Sobel [9] describes the impact of this problem and efforts to solve it in the days of the early great sea navigators.

Given modern GPS systems it is easy to determine one’s position to good accuracy outdoors when there is an adequate view of the sky. However, the application challenge is to provide guidance to the user leading them along a route from one point to another.

One hears many stories and jokes about GPS navigation systems leading users astray. Whilst this is occasionally for technical reasons – failure to obtain a fix, or positioning errors – more often than not the problem lies with the navigation aspects: for example old or incorrect map data or lack of clarity in the guidance instructions.