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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Geographical feature | 2/2 | https://en.wikipedia.org/wiki/Geographical_feature | reference | science, encyclopedia | 2026-05-05T07:20:28.730253+00:00 | kb-cron |
Cartographic features are types of abstract geographical features, which appear on maps but not on the planet itself, even though they are located on the planet. For example, grid lines, latitudes, longitudes, the Equator, the prime meridian, and many types of boundary, are shown on maps of Earth, but do not physically exist. They are theoretical lines used for reference, navigation, and measurement.
== Features and Geographic Information ==
In GIS, maps, statistics, databases, and other information systems, a geographic feature is represented by a set of descriptors of its various characteristics. A common classification of those characteristics has emerged based on developments by Peuquet, Mennis, and others, including the following :
Identity, the fact that a feature is unique and distinct from all other features. This does not have an inherent description, but humans have created many systems for attempting to express identity, such as names and identification numbers/codes. Existence, the fact that a feature exists in the world. At first, this may seem trivial, but complex situations are common, such as features that are proposed or planned, abstract concepts (e.g., the Equator), under construction, or that no longer exist. Kind (also known as class, type, or category), one or more groups to which a feature belongs, typically focused on those that are most fundamental to its existence. It thus completes the sentence "This is a _________." These are generally in the form of common nouns (tree, dog, building, county, etc.), which may be isolated or part of a taxonomic hierarchy. Relationships to other features. These may be inherent if they are crucial to the existence and identity of the feature, or incidental if they are not crucial, but "just happen to be." These may be of at least three types: Spatial relations, those that can be visualized and measured in space. For example, the fact that the Potomac River is adjacent to Maryland is an inherent spatial relation because the river is part of the definition of the boundary of Maryland, but the overlap relation between Maryland and the Delmarva Peninsula is incidental, as each would exist unproblematically without the other. Meronomic relations (also known as partonomy), in which a feature may exist as a part of a larger whole, or may exist as a collection of parts. For example, the relationship between Maryland and the United States is a meronomic relation; one is not just spatially within the boundaries of the other, but is a component part of the other that in part defines the existence of both. Genealogical relations (also known as parent-child), which tie a feature to others that existed previously and created it (or from which it was formed by another agent), and in turn to any features it has created. For example, if a county were created by the subdivision of two existing counties, they would be considered its parents. Location, a description of where the feature exists, often including the shape of its extent. While a feature has an inherent location, measuring it for the purpose of representation as data can be a complex process, such as requiring the invention of abstract spatial reference systems, and the necessary employment of cartographic generalization, including an expedient choice of dimension (e.g., a city could be represented as a region or as a point, depending on scale and need). Attributes, characteristics of a feature other than location, often expressed as text or numbers; for example, the population of a city. In geography, the levels of measurement developed by Stanley Smith Stevens (and further extended by others) is a common system for understanding and using attribute data. Time is fundamental to the representation of a feature, although it does not have independent temporal descriptions. Instead, expressions of time are attached to other characteristics, describing how they change (thus, they are analogous to adverbs in common discourse). Any of the above characteristics is mutable, with the possible exception of identity. For example, the lifespan of a feature could be considered as the temporal extent of its existence. The location of a city can change over time as annexations expand its extent. The resident population of a country changes frequently due to immigration, emigration, birth, and death. The descriptions of features (i.e., the measured values of each of the above characteristics) are typically collected in Geographic databases, such as GIS datasets, based on a variety of data models and file formats, often based on the vector logical model.
== See also == Geographical field Geographical location Human geography Landscape Physical geography Simple Features
== References ==