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Topographic and thematic maps are the two basic map types. The main
difference between them is their contents. Topographic maps, as the name
implies, contain mainly topographic information such as water bodies,
contours, and vegetation covers. To these, we often add man-made features
such as settlements, transportation networks, and major structures. They
are general-purpose maps in that their contents are useful to a larger
group of users and they often form the base of thematic maps. For this
reason, they are mostly produced by national or regional mapping
organizations according to well-defined specifications.
Thematic maps concentrate on the portrayal of a small number of geographical phenomena, and they are more specialized than topographic maps. Common types are soil maps, geological maps, population distribution maps, and land use distribution maps. They are not just produced by professional map makers but also by a much broader group of amateurs who need thematic maps for research, marketing, presentation, or other reasons. Whenever there is a need to include topographic features, thematic cartographers often base them on the official topographic maps. In this chapter, we will create a land use distribution map using the parcels as the base. To produce such a map, we will first identify the classes of land use to show and the colours to show them with. In this example, we will show the distribution of office complexes and retail stores. The method involved is quite simple - retrieve one type of land use from the database at a time and colour fill the selected parcels.
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Produce a land use distribution map.
Save the selections. If you refresh the display, all the colour fills will disappear. Using the fill polygons command again will only colour the last selection consisting of retail stores. To avoid losing a selection, you can add it to an accumulation before starting a new one.
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