Wavelength change resulting from relative motion of source and detector.

Well-defined set.

Measure of the pairs of values of an attribute type that assigns a numeric value that is positive, symmetric and satisfies the triangular inequality.

The minimum amount of information that needs to be provided by a data supplier to convey to an inquirer the nature and content of the data resource that it holds.

Position described by a single set of coordinates within a coordinate reference system.

[data capture] The process of converting the geographic features on an analog map into digital format using a digitizing tablet, or digitizer, which is connected to a computer. Features on a paper map are traced with a digitizer puck, a device similar to a mouse, and the x,y coordinates of these features are automatically recorded and stored as spatial data.

Source: http://support.esri.com/en/other-resources/gis-dictionary/term/digitizing

[editing] When you digitize in a GIS, you are creating geographic computer-compatible stored data with lines, points and polygons in a spatial database.

[file format] DTM is a bare earth representation of the Earth’s surface that is augmented natural features such as ridges and breaklines.

[file format] A digital surface model is an elevation that includes the top of buildings, tree canopy, powerlines and other features above the bare earth. For example, the first return of LiDAR consists of a DSM.

[file format] DRG is a digital version map of USGS topographic maps. They include imagery (NAIP), roads, place names, hydrography, elevation contours and boundaries.

[file format] DOQ is a geometrically-corrected photograph produced by the USGS. Orthoimages are geometrically corrected and have an area of interest with a scale of 1:40,000. The spatial resolution is about 1 meter pixels.

Integer value representing a measurement as detected by a sensor

[file format] DLG is vector data format developed and distributed by the United States Geological Survey (USGS). DLGs depict information about geographic features about terrain, administrative, hydrography, transportation, man-made features and more.