OpenStreetMap uses three basic data structures to represent physical features on the ground: nodes, ways, and relations. Nodes are the most basic data structure and represent a single point in space. They can be used to represent things like individual streetlights, fire hydrants, or trees. Ways are used to represent linear features, such as roads or rivers. A way is a series of connected nodes that create a line or path. For example, a road might be represented as a way made up of multiple nodes that define its shape and length. Relations are used to represent more complex features that cannot be easily represented as a single way or node. A relation can be thought of as a container that holds multiple nodes and ways and describes the relationship between them. For example, a park might be represented as a relation that contains multiple ways for the different paths and roads within the park, as well as nodes for various features like benches, fountains, or playgrounds. The following are examples of these data structures:
Node: This example shows the representation of a node, indicating where a public bench is present (Fig. 6a)
Way: This example shows the representation of a way, indicating where a building is present (Fig. 6b)
Relation: This example shows the representation of a relation, indicating the grouping of buildings with elements inside it (Fig. 6c)
More information can be found at the WikiOSM website.
