Introduction to vectors and geometry - ..
- 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