Just like a Microsoft Word Document, the output obtained from a GIS has to be formatted and edited with respect to the situation. The design is an integral part of the output and ensures effective communication from the developer to the user.
Some Problems That Might Arise
A poorly designed GIS output could have random colors used without the proper scaling or the wrong column widths/sizes of objects. Screen display considers more parameters than paper.
The combination of science, technique and aesthetics has progressed over the years to give birth to graphic output design. This tackles all the issues that deal with graphic output.
A variety of techniques are used to point to and locate features on a map which include symbols, colors, sizes and labels. Amongst all of these labels are the most versatile and can be used to describe any point, line or area.
The problem arises when positioning these labels. The rules provided by Imhof (1975) are not easy to follow when using a GIS especially while working on a low resolution screen.
The Basic Rules of Imhof
- The labels on maps should be legible.
- Easily identifiable with their corresponding features.
- They should not overlap.
- Size of the label should cover the whole feature.
- Employ different font styles to indicate the hierarchy of the features.
- Should not crowd the area or have even distance between them.
All these rules cannot be followed to the dot but there needs to be balance between the opposing objectives.
Significant Labeling Problem: Over posting
A map densely packed with labels that overlap each other destroys the purpose of the labels. These overlapping labels are known as the over posting phenomenon.
For point features, the label should be above and to the right of the point. The issue occurs because there are a large number of positions on a small scale. The positions must be limited by taking into account only a fixed number of positions.
Significant Labeling Problem: Polygon Labeling
A polygon or a shape with four or more sides is no easy feat to tackle. The label for this shape should be in the center and can be curved to fit inside.
The polygon can be labeled using the following techniques:
- Labeling on centroid of polygon but this may cause a long label to be multi-line and it does not represent the extent of the shape.
- A rectangle inside the polygon but the ratio of the rectangles length and width is to be taken in to consideration.
- Skeleton; which shrinks the polygon leaving behind a dotted line of the vertices.
All these rules and approaches are combined to produce the best possible result.
The Code of Graphical Excellence
Basically, Tufte introduced the ethics and principles of graphical excellence in 1983. The main objective here is to convey the maximum number of ideas using the minimum amount of time, ink and area. The graphics are edited and useless ink is removed. All the graphical elements are assembled several times to obtain the perfect graph.
Designing a Graphic Output
A GIS output must comprise of proper symbols, labels and objects with the relationships between them.
The input and output scale must be consistent so the map is not too cluttered and the data representation is not inaccurate. There is a scale on all forms of graphic outputs. The scales roughly indicate the data and are not very accurate.
A base map provides with all the other prominent landmarks and locations in an area to allow the user to find a particular point and make educated decisions using all the information given. Base maps provide an added layer of detail to the output. The information in a base map is normally in vector form.
General Graphic Design
As a final addition, the output is made more human friendly. Even though it takes a lot more time and money professionals prefer this feature of the GIS.
- Screen Display
A display screen has the added bonus of being able to zoom in or out and uses colors and animations. The output can display some information and allow access to more if user requires it.
- Scene Generation
A realistic scene can be produced which is very close to reality. For example, a white-water rafting expedition thorough a valley. The scene generation would show the surrounding hills, flowing river and vegetation found in the area from a rafters’ perspective.