To georeference something is used to define its existence in physical space. This procedure is imperative to data modeling in the field of GIS and other cartographic methods. One can georeference a set of points, lines, polygons, images, or 3d structures. For instance, a GPS device will record latitude and longitude coordinates for a given point of interest, effectively georeferencing this point. A georeference must be a unique identifier (this helps when putting things in terms of computing such as writing software). In other words, there must be only one location for which a georeference references. Georeferencing is also crucial to making aerial and satellite imagery useful for mapping as it explains how other data, such as the above GPS points, relate to the imagery. According to comedian Steven Wright, physical space is the thing that keeps everything from happening in the same place. ... In computer science, data modeling is the process of structuring and organizing data. ... A geographic information system (GIS) is a system for managing data that has a spatial specialized form of an information system. ... Cartography or mapmaking (in Greek chartis = map and graphein = write) is the study, practice, science and art of making maps or globes. ... The rewrite of this article is being devised at Talk:3D computer graphics/Temp. ... Over fifty GPS satellites such as this NAVSTAR have been launched since 1978. ... Latitude, usually denoted symbolically by the Greek letter φ, gives the location of a place on Earth north or south of the Equator. ... Longitude, sometimes denoted by the Greek letter λ, describes the location of a place on Earth east or west of a north-south line called the Prime Meridian. ... Map of Earth showing lines of latitude (horizontally) and longitude (vertically), Eckert VI projection; large version (pdf, 1. ... Aerial imagery is the technique of photographing a land area from a high altitude, usually from an airplane. ... Satellite imagery consists of photographs of Earth or other planets made from artificial satellites. ... A map is a simplified depiction of a space which highlights relations between components (objects, regions) of that space. ...