Geometric primitive in the context of Direct manipulation interface

Vector graphics are a form of computer graphics in which visual images are created directly from geometric shapes defined on a Cartesian plane, such as points, lines, curves and polygons. The associated mechanisms may include vector display and printing hardware, vector data models and file formats, as well as the software based on these data models (especially graphic design software, computer-aided design, and geographic information systems). Vector graphics are an alternative to raster or bitmap graphics, with each having advantages and disadvantages in specific situations.

While vector hardware has largely disappeared in favor of raster-based monitors and printers, vector data and software continue to be widely used, especially when a high degree of geometric precision is required, and when complex information can be decomposed into simple geometric primitives. Thus, it is the preferred model for domains such as engineering, architecture, surveying, 3D rendering, and typography, but is entirely inappropriate for applications such as photography and remote sensing, where raster is more effective and efficient. Some application domains, such as geographic information systems (GIS) and graphic design, use both vector and raster graphics at times, depending on purpose.

A proportional symbol map or proportional point symbol map is a type of thematic map that uses map symbols that vary in size to represent a quantitative variable. For example, circles may be used to show the location of cities within the map, with the size of each circle sized proportionally to the population of the city. Typically, the size of each symbol is calculated so that its area is mathematically proportional to the variable, but more indirect methods (e.g., categorizing symbols as "small," "medium," and "large") are also used.

While all dimensions of geometric primitives (i.e., points, lines, and regions) on a map can be resized according to a variable, this term is generally only applied to point symbols, and different design techniques are used for other dimensionalities. A cartogram is a map that distorts region size proportionally, while a flow map represents lines, often using the width of the symbol (a form of size) to represent a quantitative variable. That said, there are gray areas between these three types of proportional map: a Dorling cartogram essentially replaces the polygons of area features with a proportional point symbol (usually a circle), while a linear cartogram is a kind of flow map that distorts the length of linear features proportional to a variable (often travel time).