GIS Dictionary

[data models] A coordinate-based data model that represents geographic features as points, lines, and polygons. Each point feature is represented as a single coordinate pair, while line and polygon features … Read more

[data models] A representation of the world using points, lines, and polygons. Vector models are useful for storing data that has discrete boundaries, such as country borders, land parcels, and … Read more

[data conversion] The conversion of raster data (an array of cell values) to vector data (a series of points, lines, and polygons).

[software] GIS software settings that allow users to control the conversion of raster data to vector data. For example, vectorization settings may allow users to select which raster cells are … Read more

[ESRI software] An ArcScan tool that allows users to manually trace raster cells and generate features to be converted from raster to vector data.

[ESRI software] In ArcGIS Network Analyst, a type of network analysis for routing a fleet of vehicles to service a set of orders with the goal of minimizing some objective … Read more

[map design] A map scale that expresses the relationship between distance on the map and distance on the ground in words; for example, “One inch represents 20 miles.”

[software] The process, using formal methods, of evaluating a system or software component to determine whether it satisfies the requirements imposed at the start of development.

1 [database structures] In databases, an alternative state of the database that has an owner, a description, a permission (private, protected, or public), and a parent version. Versions are not … Read more

[database structures] The process of reconciling two versions of a dataset into a common version. If conflicting edits have been made in either of the merged versions, these conflicts are … Read more

[database structures] The process of updating a version of a dataset with changes made in another version. Using this technique, a version can remain up to date with changes even … Read more

[Euclidean geometry] One of a set of ordered x,y coordinate pairs that defines the shape of a line or polygon feature.

[coordinate systems] A reference system that defines the location of z-values relative to a surface. The surface may be gravity related, such as a geoid, or a more regular surface … Read more

[cartography] A multiplier applied uniformly to the z-values of a three-dimensional model to enhance the natural variations of its surface. Scenes may appear too flat when the range of x- … Read more

[geodesy] A geodetic datum for any extensive measurement system of heights on, above, or below the earth’s surface. Traditionally, a vertical geodetic datum defines zero height as the mean sea … Read more

[aerial photography] An aerial photograph taken with the camera lens pointed straight down.

[ESRI software] In ArcGIS, a parameter that offsets the z-origin from the surface of a vertical coordinate system. The vertical shift is similar in effect to the false easting or … Read more