With a paper map you can only view the information that is present on the map at the scale provided. You could take a closer look if you use a magnifying glass if you wanted to look at a specific detail. But apart from that if you wanted additional information you would have to look at more detailed maps of the area of interest.
To a certain extent the same could be said of maps within a GIS in that, when you zoom into an area of interest, the system may show more detail through a secondary layer. This layer may only be visible at certain predefined scales. To the user this may not be apparent but it is an extremely powerful feature of all desktop GIS. As you zoom in your map scale automatically changes to reflect the greater detail within the map. This scale feature is normally expressed as a ratio. For instance if the scale of a map is 1:1,000,000, it means that the features are expressed as being 1,000,000 smaller than their actual size. Zooming in however does not actually change the details of any of the map's features. A road will still have the same turns and a lake the same outline. The main difference is the level of detail that is being revealed with the ability to zoom in and out. Again, remember that the level of detail depends on the layers within the map in much the same way as in a paper map. A paper map of the world for example will not show as much detail of the shape of South Africa as would specific map of that country.
Besides shape and location there is much more to a feature. Attribute data can contain information about a shape including its name (countries, towns etc), its length (roads, rivers etc), its perimeter and area (lakes, county boundaries etc), population, employment and environment data are often included. In fact there is no limit to the amount and variation of relevant data that can be linked to features within a map. This data is stored in tables which are linked to specific layers within the GIS. This data is referred to as attribute data and consists of records (rows) for each feature in the layer and fields (columns) for type of information within the table.
If you highlight a feature on your map, such as a country within a map of the world, you will also highlight a corresponding record within the attribute data table. In the same way, if you highlight a record within the attribute data table you will highlight that feature within the map. Most GIS will allow you to then automatically zoom in to the area of the highlighted record within the map window.
Because there is a link between features and attribute data it is possible to ask questions about data in the attribute data table and then have the information show within the map window. If you have appropriate population information you could find out where population is highest within the world.
Similarly, information on climate, energy and many other important factors can be better understood through the creation of thematic maps. These maps use colours and symbols applied to features to reflect their attribute data.
If you would like to further explore how GIS could help your organisation jps services offers one and two day training courses in QGIS, ArcGIS and MapInfo.
Besides shape and location there is much more to a feature. Attribute data can contain information about a shape including its name (countries, towns etc), its length (roads, rivers etc), its perimeter and area (lakes, county boundaries etc), population, employment and environment data are often included. In fact there is no limit to the amount and variation of relevant data that can be linked to features within a map. This data is stored in tables which are linked to specific layers within the GIS. This data is referred to as attribute data and consists of records (rows) for each feature in the layer and fields (columns) for type of information within the table.
If you highlight a feature on your map, such as a country within a map of the world, you will also highlight a corresponding record within the attribute data table. In the same way, if you highlight a record within the attribute data table you will highlight that feature within the map. Most GIS will allow you to then automatically zoom in to the area of the highlighted record within the map window.
Because there is a link between features and attribute data it is possible to ask questions about data in the attribute data table and then have the information show within the map window. If you have appropriate population information you could find out where population is highest within the world.
Similarly, information on climate, energy and many other important factors can be better understood through the creation of thematic maps. These maps use colours and symbols applied to features to reflect their attribute data.
If you would like to further explore how GIS could help your organisation jps services offers one and two day training courses in QGIS, ArcGIS and MapInfo.
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