GIS Dictionary

[coordinate systems] In a spherical coordinate system, the vertical line that runs parallel to the earth’s rotation, passing through 90 degrees north latitude, and perpendicular to the equatorial plane, where … Read more

The value for a given surface location that represents an attribute other than position. In an elevation or terrain model, the z-value represents elevation; in other kinds of surface models, … Read more

[coordinate systems] A conversion factor used to adjust vertical and horizontal measurements into the same unit of measure. Specifically, the number of vertical units (z-units) in each horizontal unit. For … Read more

[statistics] A statistical measure of the spread of values from their mean, expressed in standard deviation units, where the z-score of the mean value is zero and the standard deviation … Read more

[coordinate systems] In raster-to-TIN conversion, the maximum allowed difference between the z-value of the input raster cell and the z-value of the output TIN at the location corresponding to the … Read more

[coordinate systems] The value for a given surface location that represents an attribute other than position. In an elevation or terrain model, the z-value represents elevation; in other kinds of … Read more

[astronomy] In astronomy, the point on the celestial sphere directly above an observer. Both the zenith and nadir lie on the observer’s meridian; the zenith lies 180 degrees from the … Read more

[ESRI software] In Survey Analyst for field measurements, a vertical angle that is formed by the intersection of two lines in a vertical plane. Zenith angles are observed on the … Read more

[linear referencing] In linear referencing, a line event whose from-measure is equal to its to-measure. A zero length line even may occur, for example, along routes, when a polygon touches … Read more

[federal government] Acronym for zone improvement plan code. A five-digit code, developed by the U.S. Postal Service, that identifies the geographic delivery area served by an individual post office or … Read more

[federal government] An enhanced ZIP Code that consists of the five-digit ZIP Code plus four additional digits that identify a specific geographic segment within the five-digit delivery area, such as … Read more

[spatial analysis] The creation of an output raster in which the desired function is computed on the cell values from the input value raster that intersect or fall within each … Read more

[ESRI software] In ArcGIS Spatial Analyst, the calculation of a statistic for each zone of a zone dataset based on values from another dataset, a value raster. A single output … Read more

1 [analysisgeoprocessing] All cells in a raster with the same value, regardless of whether or not they are contiguous. 2 [geocoding] Additional information about a location or address, used to … Read more

The area in a TIN layer for which values (elevation, slope, and aspect) are calculated. When a TIN layer is clipped to a smaller size to create a more focused … Read more

[local government] The application of local government regulations that permit certain land uses within geographic areas under the governments jurisdiction. Zoning regulations typically set a broad category of land use … Read more

[software] To display a larger or smaller region of an on-screen map or image.