[转帖]What is GIS

What is GIS?

                  来自 The University of Edinburgh 的解释
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Geographical Information Systems (GIS) can be regarded as the high- tech equivalent of the map. An individual map contains a lot of information which is used in different ways by different individuals and organisations. It represents the means of locating ourselves in relation to the world around us. Maps are used in diverse applications; from locating telephone wires and gas mains under our streets, to displaying the extent of de-forestation in the Brazilian Amazon.
The map has been in existence in much the same form for thousands of years. In the traditional form it suffers from a number of problems. Firstly maps are static and therefore difficult and expensive to keep up to date. This relates to a second problem, in that because they are static they lose flexibility, for example maps exist as discrete sheets and inevitably your area of interest lies on the corner of four adjacent sheets. In addition maps are often very complex and may require an expert to extract the particular data which are of interest.

GIS provides the facility to extract the different sets of information from a map (roads, settlements, vegetation, etc.) and use these as required. This provides great flexibility, allowing a paper map to be quickly produced which exactly meets the needs of the user. However, GIS goes further, because the data are stored on a computer, analysis and modelling become possible. For example, one might point at two buildings, ask the computer to describe each from an attached database (much more information than could be displayed on a paper map) and then to calculate the best route between these.