At the very basic, student ought to gain skills in data visualization to enable them accomplish the last of the functions of GIS, output. Map layout, cartographic design and symbology is at the core.
Understanding of map production for spatial data is very crucial. Map production is the process of arranging map elements on a sheet of paper in a way that, even without many words, the average person can understand what it is all about.
Maps are usually produced for presentations and reports. a map has to be effective in communicating spatial information. Maps can be hardcopy or digital (display, pdf, images, web maps)
Design of Maps in GIS
Maps are graphic representations of the real world or part of it, where all some of the features may be exaggerated to show them. It is a GIS visualization technique, in addition to reports, charts and tables. Map elements, which are components of a map, should be well arranged/designed for effective communication. Common elements of a map are the title, map body, legend, north arrow, scale bar, acknowledgement, and map border (see figure 5.1). Other elements that might be added are e.g. a graticule, or name of the map projection (CRS); datum, coordinate system, dates, producers/custodian.
The map body is, of course, the most important part of the map because it contains the map information. The other elements support the communication process and help the map reader to orientate himself and understand the map topic. For example, the title describes the subject matter and the legend relates map symbols to the mapped data.
The map title is very important because it is usually the first thing a reader will look at on a map. It can be compared with a title in a newspaper. It should be short but give the reader a first idea of what the map is about.
Figure: Common Map Elements
The map border is a line that defines exactly the edges of the area shown on the map. When printing a map with a graticule (which we describe further down), you often find the coordinate information of the graticule lines along the border lines, as you can see in the figure 5.1
A map is a simplified representation of the real world and map symbols are used to represent real objects. Without symbols, we wouldn’t understand maps. To ensure that a person can correctly read a map, a map legend is used to provide a key to all the symbols used on the map. It contains icons, each of which will represent a type of feature represented in the map.
A north arrow (sometimes also called a compass rose) is a figure displaying the main directions, North, South, East and West. On a map it is used to indicate the direction of North.
The scale of a map is the value of a single unit of distance on the map, representing distance in the real world. The values are shown in map units (meters, feet or degrees). The scale can be expressed in several ways, for example, in words, as a ratio or as a graphical scale bar
Scale can be expressed as:
- Words: g. one millimeter on maps represents a thousand meters on the ground.
- Representative fraction (RF), where map distance and respective ground distance in the real world is represented as a ratio. E.g. 1:25,000 or 1/25,000. 25,000 in the ratio is called the scale denominator
- Bar scale: where scale is represented as a graphic. It shows measured distances on the map
Figure: A map scale can be expressed in words (a), as a ratio (b), or as graphic or bar scale (c)
In the acknowledgment area of a map it is possible to add text with important information. For example information about the quality of the used data can be useful to give the reader an idea about details such as how, by whom and when a map was created.
Graticule and Grids:
A graticule is a network of curved lines overlain on a map to make spatial orientation easier for the reader. The lines can be used as a reference. As an example, the lines of a graticule can represent the earth’s parallels of latitude and meridians of longitude for geographical coordinate system. . Grids can also be applied for projected coordinate system instead of graticules. Grids are networks of parallel and orthogonal straight lines of Eastings and northings in projected cylindrical projections.
Figure : Graticule