Excluding borders, each sheet was 44 cm high and (depending on latitude) up to 66 cm wide. ġ913 saw the beginning of the International Map of the World initiative, which set out to map all of Earth's significant land areas at a scale of 1:1 million, on about one thousand sheets, each covering four degrees latitude by six or more degrees longitude. In the United States, the national map-making function which had been shared by both the Army Corps of Engineers and the Department of the Interior migrated to the newly created United States Geological Survey in 1879, where it has remained since.
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Īs they evolved, topographic map series became a national resource in modern nations in planning infrastructure and resource exploitation. As such, elevation information was of vital importance.
Topographic surveys were prepared by the military to assist in planning for battle and for defensive emplacements (thus the name and history of the United Kingdom's Ordnance Survey). Global indexing system first developed for International Map of the World
Maps were among the first artifacts to record observations about topography. The study or discipline of topography is a much broader field of study, which takes into account all natural and man-made features of terrain. However, in the vernacular and day to day world, the representation of relief (contours) is popularly held to define the genre, such that even small-scale maps showing relief are commonly (and erroneously, in the technical sense) called "topographic". Other authors define topographic maps by contrasting them with another type of map they are distinguished from smaller-scale " chorographic maps" that cover large regions, " planimetric maps" that do not show elevations, and " thematic maps" that focus on specific topics. These maps depict in detail ground relief (landforms and terrain), drainage (lakes and rivers), forest cover, administrative areas, populated areas, transportation routes and facilities (including roads and railways), and other man-made features. Natural Resources Canada provides this description of topographic maps: Official topographic maps also adopt a national grid referencing system. A topographic map series uses a common specification that includes the range of cartographic symbols employed, as well as a standard geodetic framework that defines the map projection, coordinate system, ellipsoid and geodetic datum. A topographic survey is typically based upon a systematic observation and published as a map series, made up of two or more map sheets that combine to form the whole map. Traditional definitions require a topographic map to show both natural and artificial features.
In modern mapping, a topographic map or topographic sheet is a type of map characterized by large- scale detail and quantitative representation of relief features, usually using contour lines (connecting points of equal elevation), but historically using a variety of methods.
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Learn more about how to create contours in FME with Community tutorials like Generate Contour Data from Points, Generate Contour Data from Raster, and Creating Time and Distance Isolines.Section of topographical map of Nablus area ( West Bank) with contour lines at 100-meter intervals. To create contours with FME, you can connect your data points containing x, y, and z coordinates to the ContourGenerator. When lines are further apart, the elevation changes more gradually and the slope is less.Ĭontour lines are also commonly used in meteorology to represent areas of equal air pressure, temperature, rainfall, and wind. Where lines are close together, the elevation is changing quickly and therefore the slope is higher. This allows viewers to distinguish the steepness of slopes. They are most commonly used on topographic maps to indicate areas of equal elevation. Contours are lines used to distinguish areas of equal measurement on both 2D and 3D models.
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