GIS Dictionary

[astronomy] The sky, considered as the inside of a sphere of infinitely large radius that surrounds the earth, on which all celestial bodies except the earth are imagined to be … Read more

1 [graphics computing] The smallest unit of information in raster data, usually square in shape. In a map or GIS dataset, each cell represents a portion of the earth, such … Read more

[analysisgeoprocessing] The process of selecting raster cells either interactively or by using a SQL query.

[data models] The dimensions on the ground of a single cell in a raster, measured in map units. Cell size is often used synonymously with pixel size.

[ESRI software] An ArcGIS Spatial Analyst function that calculates a statistic for each cell of an output raster that is based on the values of each cell in the same … Read more

[modeling] A mathematical construction consisting of a row or grid of cells in which each cell has an initial valuefrom a known and limited number of possible valuesand all cells … Read more

[federal government] The smallest geographic entity for which the U.S. Census Bureau tabulates decennial census data. Many blocks correspond to city blocks bounded by streets, but blocks in rural areas … Read more

[federal government] Any one of various types of precisely defined geographic areas used by the U.S. Census Bureau to collect and aggregate data. The largest unit of area is the … Read more

[federal government] A small, statistical subdivision of a county that usually includes approximately 4,000 inhabitants but may include from 2,500 to 8,000 inhabitants. A census tract is designed to encompass … Read more

[Euclidean geometry] The point in a circle or in a sphere equidistant from all other points on the object.

[data capture] A line digitized along the center of a linear geographic feature, such as a street or a river, that at a large enough scale would be represented by … Read more

[data capture] The generation of vector features along the center of connected cells. It is typically used for vectorizing scanned parcel and survey maps.

In aerial photography, the point at the exact center of an aerial photograph.

[coordinate systems] The line of longitude that defines the center and often the x-origin of a projected coordinate system. In planar rectangular coordinate systems of limited extent, such as state … Read more

[data capture] The geometric center of a feature. For line, polygon, or three-dimensional features, it is the center of mass (or center of gravity) and may fall inside the feature, … Read more