Spatial Referencing

GPS receivers are everywhere these days. Trucking and taxi companies use them to track vehicle locations, cars use them for navigation, some can even alert emergency services to your location if you've been involved in an accident.

GPS receivers are making it easier than ever for us to determine our position on the surface of the Earth.

To be useful though, these positions must all be related to a single, common 'reference system'.

Why Do I need a reference system?

Think of it this way, suppose you were to give directions to your house to a friend. After carefully following your directions, they arrive in your neighbourhood only to find that the all the houses in the area have 2 house numbers and 2 houses have the same address you've given them.

Confusing right? Well, we've discovered that we need to be very specific in our addressing; each property should have a unique address.

Well, in Canada there exist a couple of different reference systems. This can lead to confusion, as any feature can be located in either reference system. That means every feature can have 2 different coordinate values. That's just like every house having 2 different addresses.

If we only had one reference system, this confusion could be eliminated.

The Canadian Spatial Reference System (CSRS) is the common reference system we use to uniquely determine our position anywhere in Canada.

The Geodetic Survey Division of Canada (NRCan) developed this system and it is their main task to see that is maintained, improved if possible and to make sure that all Canadians can gain access to the CSRS products and services.