There have been many definitions of a geographical information system which have successfully covered the elements of what such a system should be. However, for the purpose of this particular discussion we will narrow the definition to that of a computer based definition of a geographic information system. This is because there is significant evidence to show that GIS is now more or less associated with digitally based computer solutions rather than paper based solutions. Accordingly we could define GIS a computer based tool which is able to convert geographic data into geographic information.
GIS systems such as ArcGIS, MapInfo and QGIS are computer software based tools which are able to convert geographic data into geographic information. These systems primarily run on personal computers utilising operating systems such as Windows, Unix and Mac OS. The significant increase in the capability and power of these desktop systems coupled with the continuing reduction in purchase costs of hardware and software mean that GIS is becoming available to a much wider and diverse audience.
For most users of GIS access to appropriate maps and underlying database information is crucial regardless of whether they use a proprietary or open source solution. Within a GIS system maps display the graphic element of data in both vector and raster format. Behind this graphical map format is the tabular data which can be as simple as an imported text file containing a few hundred rows of data or as powerful as a multi user database containing many thousands or even millions of records. This kind of data can be interrogated by using query languages such as SQL (structured query language).
Many of the tasks which required time consuming activities, when only paper based systems were available, are now easily and quickly achieved with a modern desktop GIS system. For instance, if you needed to find property parcels of a certain size, define whether they were vacant or for sale, commercial rather than private, not on a flood plain, located close to major routes and situated in an urban location you would find this an easy task with GIS systems such as ArcGIS, MapInfo or QGIS. The GIS system however, would of course require the appropriate map layers and underlying attribute data in order to complete the analysis. By creating spatial queries, only the property parcels would be highlighted which were of the correct size and availability. Additional appropriate map layers containing flood plain, major routes and location data would then reveal whether these parcels met the defined criteria and so were viable for consideration. This is an example of the way geographical information systems combine both database systems with mapping to form a powerful and effective means of analysis.
For most users of GIS access to appropriate maps and underlying database information is crucial regardless of whether they use a proprietary or open source solution. Within a GIS system maps display the graphic element of data in both vector and raster format. Behind this graphical map format is the tabular data which can be as simple as an imported text file containing a few hundred rows of data or as powerful as a multi user database containing many thousands or even millions of records. This kind of data can be interrogated by using query languages such as SQL (structured query language).
Many of the tasks which required time consuming activities, when only paper based systems were available, are now easily and quickly achieved with a modern desktop GIS system. For instance, if you needed to find property parcels of a certain size, define whether they were vacant or for sale, commercial rather than private, not on a flood plain, located close to major routes and situated in an urban location you would find this an easy task with GIS systems such as ArcGIS, MapInfo or QGIS. The GIS system however, would of course require the appropriate map layers and underlying attribute data in order to complete the analysis. By creating spatial queries, only the property parcels would be highlighted which were of the correct size and availability. Additional appropriate map layers containing flood plain, major routes and location data would then reveal whether these parcels met the defined criteria and so were viable for consideration. This is an example of the way geographical information systems combine both database systems with mapping to form a powerful and effective means of analysis.
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