In the previous chapter we have loo

In the previous chapter we have looked at how you can display maps and tables in
ILWIS. Now we will see more in depth how the data are structured. We will treat the
structure of spatial data.
Spatial features are represented in ILWIS in the following ways:
- Points. Many items can be represented as single points on a map. Points may refer
to rainfall stations, houses, field observations, sampling points, etc.
- Lines. Linear features such as roads, drainage lines or contour lines.
- Areas. Features which occupy a certain area, such as land use units (e.g. forest),
geological units, etc.
The spatial entities described above can be represented in digital form in two data
models (Figure 2.1): vector models or raster models. Both models store details on the
location of entities and their value, class name or identifier. The main difference
between the two data models is the way they store and represent the locations.