GIS Glossary/K

GIS Glossary

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kernel
On a raster, an analysis boundary or processing window within which cell values affect calculations and outside which they do not. Filters are used mainly in cell-based analysis where the value of a center cell is changed to the mean, the sum, or some other function of all cell values inside the filter. A filter moves systematically across a raster until each cell has been processed. Filters can be of various shapes and sizes, but are most commonly three-cell by three-cell squares.

key
An attribute or set of attributes in a database that uniquely identifies each record.

key attribute
An attribute or set of attributes in a database that uniquely identifies each record. A primary key allows no duplicate values and cannot be null.

keyboard shortcut
A keystroke combination that executes a command that might otherwise require the use of a mouse. For example, Ctrl+C is a well-known keyboard shortcut for copying a selection in Windows.

keycode
A unique number in the feature line of a license or authorization file that controls access to software. Keycodes are based on a unique identifier. In ArcEditor Concurrent Use on Windows, for example, the hardware key number provides this unique identifier. The License Manager compares the keycodes in the license file and the unique identifier for a computer to allow access to the software. If the keycode and the unique identifier agree, then software access is granted.

keyframe
In an animation in ArcMap, ArcScene, or ArcGlobe, a snapshot of an object's properties at a certain time.

keyword
A significant word from a document that is used to index or search content.

kinematic positioning
Determining the position of an antenna on a moving object such as a ship or an automobile.

knockout
In offset printing, an area that has been defined to cut through or mask specific layers of colored inks. Knockouts are used to ensure that certain ink colors are not mixed with inks that are laid down after them.

knowledge base
A database of information about a subject, used in expert systems.

known point
A surveyed point that has an established x,y coordinate value. Known points are used in survey operations to extend survey computations into a project area.

Kohonen map
A map that uses a neural network algorithm to classify and illustrate associations in complex datasets, and reveal multidimensional patterns. A similar set of methods produces maps referred to as self-organizing maps (SOMs). Kohonen maps are named for the Finnish engineer Teuvo Kohonen.

kriging
An interpolation technique in which the surrounding measured values are weighted to derive a predicted value for an unmeasured location. Weights are based on the distance between the measured points, the prediction locations, and the overall spatial arrangement among the measured points. Kriging is unique among the interpolation methods in that it provides an easy method for characterizing the variance, or the precision, of predictions. Kriging is based on regionalized variable theory, which assumes that the spatial variation in the data being modeled is homogeneous across the surface. That is, the same pattern of variation can be observed at all locations on the surface. Kriging was named for the South African mining engineer Danie G. Krige (1919-).