Such points, lines and areas are represented as a list of co-ordinates instead of as a picture or a graph. Map features are logically organized into sets of layers or themes of information. Cutout of a digital Polish cadastral map. Relationships are very important, as they help the user to understand situations and to make decisions. In digital maps spatial relationships are depicted using topology.
Topology is a mathematical procedure for explicitly defining spatial relationships.
The information is stored as attributes of the geographically represented feature. The first solution is used mainly to provide simple information on particular objects like the object's name, date of placement, etc. The latter case requires an external database, the records of which are linked with corresponding graphical map objects. Graphic and tabular data integration for Polish cadastral maps. The concept described above applies to more than just keeping track of features and their attributes.