1.2 The real world and representati

1.2 The real world and representations of it

One of the main uses of GIS is as a tool to help us make decisions. specifically , we often want to know the best location for a new facility, the most likely sites for mosquito habitat, or perhaps identify areas with a high risk of flooding so that we can formulate the best policy for prevention. In using GIS to help make these decisions, we need to represent some part of the real world as it is, as it was, or perhaps as we think it will be. We need to restrict ourselves to ‘some part’ of the real world simply because it cannot be represented completely.
The EI Nino system discussed earlier in this chapter has as its purpose the ad- ministration of SST and WS in various places in the equatorial Pacific Ocean, and to generate georeferenced, monthly overviews from these. If this is its complete purpose, the system does not need to store data about the ships that moored the buoys, the manufacture date of the buoys et cetera. All this data is irrelevant for the purpose of the system.
The fact that we can only represent parts of the real world teaches us to be hum- ble about the expectations that we can have about the system: all the data it can possibly generate for us in the future will be based upon the information which we provide the system with. Often, we are dealing with processes or phenom- ena that change rapidly, or which are difficult to quantify in order to be stored in a computer. It follows that the ways we collect, organise and structure data from the real world plays a key part in this process.
If we have done our job properly, a computer representation of some part of the real world, will allow us to enter and store data, analyse the data and transfer it to humans or to other systems.