The document discusses the role of vectors in data visualization, emphasizing their mathematical precision and scalability in representing complex data sets. It describes vector data as one of the two primary types of spatial data in GIS, defining various features such as point, polyline, and polygon, each characterized by their geometric attributes. GIS applications utilize vector data for creating maps, navigation, object identification, and environmental analysis.

1. Introduction to vectors and geometry
• The landscape of data visualization is constantly evolving, and at
the forefront of this evolution is the use of vectors.
• Vectors, with their mathematical precision and scalability, are
transforming the way we visualize complex data sets.
• The role of vectors is emerging in data visualization techniques,
offering insights into how they enhance clarity, efficiency, and
interactivity.

2. Vector data provide a way to represent real world features within the GIS
environment. A feature is anything you can see on the landscape. Imagine
you are standing on the top of a hill. Looking down you can see houses, roads,
trees, rivers, and so on (see Fig. 3.28). Each one of these things would be
a feature when we represent them in a GIS Application. Vector features
have attributes, which consist of text or numerical information
that describe the features.
Vector data

3.  A vector feature has its shape represented using geometry. The geometry
is made up of one or more interconnected vertices.
 A vertex describes a position in space using an X, Y and optionally Z axis.
Geometries which have vertices with a Z axis are often referred to
as 2.5D since they describe height or depth at each vertex, but not both.
 Vector data is one of two primary types of spatial data in geographic
information systems (GIS) – the other being raster data.
 GIS applications can perform various tasks such as creating maps,
navigation applications, location, object identification, and environmental
analysis using vector data.

4. A point feature is described by its X, Y and optionally Z coordinate. The point attributes
describe the point e.g. if it is a tree or a lamp post.
When a feature’s geometry consists of only a single vertex, it is referred to as
a point feature

5. A polyline is a sequence of joined vertices. Each vertex has an X, Y (and optionally Z)
coordinate. Attributes describe the polyline.
Where the geometry consists of two or more vertices and the first and last
vertex are not equal, a polyline feature is formed

6. A polygon, like a polyline, is a sequence of vertices. However in a polygon, the first and
last vertices are always at the same position.
Where three or more vertices are present, and the last vertex is equal to the first,
an enclosed polygon feature is formed