Database management system (DBMS)
A set of computer programs for organizing the information in a database. A DBMS supports the structuring of the database in a standard format and provides tools for data input, verification, storage, retrieval, query, and manipulation.

Rubber sheeting
A procedure to adjust vector or raster features in a nonuniform manner. Digitized links (controlpoints) representing from- and to-locations are used to define and transform the adjustment.

Rectification
The process by which an image or grid is converted from image coordinates to real-world coordinates. Rectification typically involves rotation and scaling of grid cells, and thus requires resampling of values.

Cartesian coordinate system
Maps identify the location of geographic objects on the earths surface. Correct identification requires a framework for defining real-world locations on the map. The plane, or Cartesian coordinate system is such a framework. The Cartesian coordinate system uses two axes: one horizontal (x), representing east-west, and one vertical (y), representing north-south. The point at which they intersect is called the origin. Locations of geographic objects are defined relative to the origin, using the notation (x,y), where x refers to the distance along the horizontal axis, and y refers to the distance along the vertical axis. The origin is defined as (0,0). The notation (2,1) records a point that is two units over in x and one unit up in y from the origin.