| Topographic Map |
Article Index for Topographic |
Shopping Topographic |
Website Links For Map |
Information AboutTopographic Map |
| CATEGORIES ABOUT TOPOGRAPHIC MAP | |
| cartography | |
| topography | |
|
Topographic maps are a variety of Map s characterized by large-scale detail and quantitative representation of Relief , usually using Contour Lines in modern mapping, but historically using a Variety Of Methods . Traditional definitions require a topographic map to show both natural and man-made features,"A topographic map is a detailed and accurate graphic representation of cultural and natural features on the ground." Centre for Topopgraphic Information - Topographic Maps: Frequently Asked Questions "Traditionally, the main division of maps is into topographic and thematic maps. Topographic maps supply a general image of the earth's surface: roads, rivers, buildings, often the nature of the vegetation, the relief and the names of the various mapped objects." M.-J. Kraak and F. Ormeling, ''Cartography: Visualization of Spatial Data'', Longman, 1996, ISBN 0-582-25953-3, p. 44. The Centre for Topographic Information provides this definition of topographic map: 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." According to Cartographer's Kraak and Ormeling, The study or discipline of Topography , while interested in relief, is actually a much broader field of study which takes into account all Natural and man made features of terrain. HISTORY Topographic maps are based on topographical surveys. Performed at large scales, these surveys are called topographical in the old sense of 's Ordnance Survey ).Peter Barber, ''The Map Book'', Weidenfeld & Nicolson, 2005, ISBN 0-297-84372-9, pp. 232, 250. As such, elevation information was of vital importance. As they evolved, topographic map series became a basic national resource in modern nations in planning infrastructure and resource exploitation. 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. 1 2 USES 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. MAP CONVENTIONS The various features shown on the map are represented by conventional signs or symbols. For example, colors can be used to indicate a classification of roads. These signs are usually explained in the margin of the map, or on a separately published characteristic sheet.Ordnance Survey, Explorer Map Symbols ; Swisstopo, Conventional Signs ; United States Geological Survey, Topographic Map Symbols . Topographic maps are also commonly called ''contour maps'' or '''''topo maps'''''. In the United States, where the primary national series is organized by a strict 7.5° grid, they are often called '''''topo quads''''' (or quadrangles). Topographic maps conventionally show Topography , or land contours, by means of Contour Line s. Contour lines are Curve s that connect contiguous points of the same Altitude ( Isohypse ). In other words, every point on the marked line of 100 m Elevation is 100 m above mean sea level. There are several rules to note when viewing topographic maps:
Of course, to determine differences in elevation between two points, the contour interval, or distance in altitude between two adjacent contour lines, must be known, and this is given at the bottom of the map. In most cases, contour intervals are consistent throughout a map. Sometimes dashed contour lines are present; these represent half the noted contour interval. These maps usually show not only the contours, but also any significant Stream s or other bodies of Water , Forest cover, built-up areas or individual buildings (depending on scale), and other features and points of interest. Today, topographic maps are prepared using Photogrammetric interpretation of Aerial Photography . Older topographic maps were prepared using traditional Surveying instruments. PUBLISHERS OF NATIONAL TOPOGRAPHIC MAP SERIES Most countries have some sort of national mapping program. Those listed below are only a small selection. Several commercial vendors supply international topographic map sets. Look for their general indexes at: Canada The Centre for Topographic Information produces topographic maps of (NTS). Centre for Topographic Information website . A government proposal to discontinue publishing of all hardcopy or paper topographic maps in favor of digital-only mapping data was shelved in 2006 after intense public opposition.http://www.cbc.ca/canada/ottawa/story/2006/10/12/map-office.html Denmark The National Survey And Cadastre Of Denmark is responsible for producing topographic and nautical geodata of Denmark , Greenland and the Faroe Islands . Kort & Matrikelstyrelsens website (in Danish). France The Institut Géographique National (or '''IGN''') produces topographic maps of France at 1:25,000 and 1:50,000. Institut Géographique National website (in French, English and German). India The Survey Of India is responsible for all topographic control, surveys and mapping of India . Department of Scientific and Technology: Survey of India Japan The Geographical Survey Institute Of Japan is responsible for base mapping of Japan. Standard map scales are 1:25,000, 1:50,000, 1:200,000 and 1:500,000 Omni Resources catalog page New Zealand Land Information New Zealand is the government agency responsible for providing up-to-date topographic mapping. LINZ topographic maps cover all of New Zealand, offshore islands, some Pacific Islands and the Ross Sea Region. Land Information New Zealand . Vector data from the New Zealand Topographic Database (NZTopo) is also available. NZTopo''Online''[http://www.nztopoonline.linz.govt.nz/ is a publicly accessible, free online service. Switzerland Swisstopo (the Federal Office of Topography) produces topographic maps of Switzerland at seven different scales. United Kingdom The ''' Topography Layer contains information about buildings, roads, woodland, administrative boundaries, etc, with just a few spot heights along the roads. For contours or a digital terrain model, a separate product called Land-Form Profile is required. United States The ''' produced by the Department Of The Interior , one of whose bureaus is USGS). An older series of maps, the 15-minute series, was once used to map the contiguous 48 states at a scale of 1:62,500, but was discontinued some time ago for maps covering the continental U.S. Each map was bounded by two Parallels and two Meridians spaced 15 minutes apart - the same area covered by four maps in the 7.5-minute series. The 15-minute series, at a scale of '''1:63,360''' (one inch representing one mile), remains the primary topographic quadrangle for the state of Alaska (and only for that particular state). Nearly 3,000 maps cover 97% of the state. The U.S.A. remains virtually the only developed country in the world without a standardized civilian topographic map series in the standard 1:25,000 or 1:50,000 metric scales, making coordination difficult in border regions (the U.S. military does issue 1:50,000 scale topo maps of the continental U.S., though only for use by members of its defense forces). The next-smallest topographic series, in terms of scale, is the 1:100,000 series. These maps are bounded by two lines of longitude and two lines of latitude. However, in this series, the lines of latitude are spaced 30 minutes apart and the lines of longitude are spaced 60 minutes, which is the source of another name for these maps; the '''30 x 60-minute''' quadrangle series. Each of these quadrangles covers the area contained within 32 maps in the 7.5-minute series. The 1:100,000 scale series is unusual in that it employs the Metric System primarily. One centimeter on the map represents one kilometer of distance on the ground. Contour Intervals , spot elevations, and horizontal distances are also specified in meters. The final regular quadrangle series produced by the USGS is the 1:250,000 scale topographic series. Each of these quadrangles in the conterminous United States measures 1 degree of latitude by 2 degrees of longitude. This series was produced by the U.S. Army Map Service in the 1950s, prior to the maps in the larger-scale series, and consists of 489 sheets, each covering an area ranging from at 30° north to at 49° north. Hawaii is mapped at this scale in quadrangles measuring 1° by 1°. USGS topographic quadrangle maps are marked with grid lines and tics around the map collar which make it possible to identify locations on the map by several methods, including the Graticule measurements of Longitude and Latitude , the Township and Section method within the Public Land Survey System , and Cartesian Coordinates in both the State Plane Coordinate System and the Universal Transverse Mercator Coordinate System . Other specialty maps have been produced by the USGS at a variety of scales. These include County maps, maps of special interest areas, such as the National Parks , and areas of scientific interest. A number of Internet sites have made these maps available on the web for affordable commercial and professional use. Because works of the U.S. Government are in the Public Domain , it is also possible to find many of these maps for free at various locations on the Internet. Georeference d map images are available from the USGS as Digital Raster Graphic s (DRGs), in addition to digital data sets based on USGS maps (notably Digital Line Graph s (DLGs) and Digital Elevation Model s (DEMs)). The Moon The United States Geological Survey has produced a map of the Moon .4 COMMERCIAL PUBLISHERS OF TOPOGRAPHIC MAPS A number of commercial publishers have created topographic maps of recreation areas, with enhanced and updated trails and facilities data on the map, and with supplementary text and graphic information about them. These publishers include:
GLOBAL 1-KILOMETER MAP This map is derived from GTOPO30 data that describes the elevation of Earth 's terrain at intervals of 30 arcseconds (approximately 1 km). It uses color and shading instead of contour lines to indicate elevation. SEE ALSO
NOTES AND REFERENCES EXTERNAL LINKS
|
|
|