It provides topographic maps and data to meet the needs of the sustainable development of the nation.
The National Mapping Information Group of Geoscience Australia is the Australian Government's national mapping agency.
Several commercial vendors supply international topographic map sets. Those listed below are only a small selection. Most countries have some sort of national mapping program.
TOPOGRAPHIC ELEVATION MAP SERIES
Publishers of national topographic map series Older topographic maps were prepared using traditional surveying instruments. Today, topographic maps are prepared using photogrammetric interpretation of aerial photography. These maps usually show not only the contours, but also any significant streams or other bodies of water, forest cover, built-up areas or individual buildings (depending on scale), and other features and points of interest. In other words, every point on the marked line of 100 m elevation is 100 m above mean sea level. Contour lines are curves that connect contiguous points of the same altitude (isohypse). Topographic maps conventionally show topography, or land contours, by means of contour lines. In the United States, where the primary national series is organized by a strict 7.5 minute grid, they are often called topo quads or quadrangles. Topographic maps are also commonly called contour maps or topo maps. These signs are usually explained in the margin of the map, or on a separately published characteristic sheet. For example, colors can be used to indicate a classification of roads. The various features shown on the map are represented by conventional signs or symbols. Topographic maps have multiple uses in the present day: any type of geographic planning or large-scale architecture earth sciences and many other geographic disciplines mining and other earth-based endeavours and recreational uses such as hiking or, in particular, orienteering, which uses highly detailed maps in its standard requirements.įor more about contour lines, see Cartographic relief depiction. 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.
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). The first multi-sheet topographic map series of an entire country, the Carte géométrique de la France, was completed in 1789. This is in contrast to older cadastral surveys, which primarily show property and governmental boundaries. Performed at large scales, these surveys are called topographical in the old sense of topography, showing a variety of landmark and landscape information. Topographic maps are based on topographical surveys. 4 Publishers of national topographic map series.
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