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Topic: Map projection


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  Map Projection Overview
Map projections are attempts to portray the surface of the earth or a portion of the earth on a flat surface.
Gall's stereographic cylindrical projection results from projecting the earth's surface from the equator onto a secant cylinder intersected by the globe at 45 degrees north and 45 degrees south.
The Peters projection is a cylindrical equal-area projection that de-emphasizes area exaggerations in high latitudes by shifting the standard parallels to 45 or 47 degrees.
www.colorado.edu /geography/gcraft/notes/mapproj/mapproj.html   (1829 words)

  
  Highbeam Encyclopedia - Search Results for Map projection
Maps are usually printed on a flat surface using various kinds of projections based on land surveys, aerial photographs and other sources.
a projection of a map of the world onto a cylinder in such a way that all the parallels of latitude have the same length as the equator, used esp. for...
The most common example is the Mercator map, a two-dimensional representation of the surface of the earth that preserves compass directions.
www.encyclopedia.com /SearchResults.aspx?Q=Map+projection   (1182 words)

  
  Map Projections: From Spherical Earth to Flat Map
Each map projection has advantages and disadvantages; the appropriate projection for a map depends on the scale of the map, and on the purposes for which it will be used.
The Azimuthal Equidistant projection is the projection used for the emblem of the United Nations.
Polyconic projection A conic projection projects information from the spherical Earth to a cone that is either tangent to the Earth at a single parallel, or that is secant at two standard parallels.
nationalatlas.gov /articles/mapping/a_projections.html   (2154 words)

  
 ToC
Map Projections - Conversions - Transformations - Interpolations
Voser 2003 - Map Projections for the Layman
Lee 1944 - On the Nomenclature and Classification of Map Projections.
www.mapref.org /contents.htm   (303 words)

  
 map projection. The Columbia Encyclopedia, Sixth Edition. 2001-05
Some projections preserve correct relative distances in all directions from the center of the map (equidistant projection); some show areas equal to (equal-area projection) or shapes similar to (conformal projection) those on a globe of the same scale; some are useful in determining direction.
Many map projections can be constructed by the use of a light source to project the features of the globe onto a piece of paper (although in practice one performs the operation mathematically rather than with a light); other projections can be constructed only mathematically.
In all cylindrical projections the meridians of longitude, which on the globe converge at the poles, are parallel to one another; in the Mercator projection the parallels of latitude, which on the globe are equal distances apart, are drawn with increasing separation as their distance from the equator increases in order to preserve shapes.
www.bartelby.com /65/ma/mapproje.html   (905 words)

  
 Map projection Summary
Cylindrical equal-area, Mercator, Miller cylindrical, oblique Mercator, and transverse Mercator are all cylindrical map projections.
The map from O to P that send each point of O to the point in P closest to it, is called the projection map from O to P. For example, suppose that O is a knot - that is a loop of string with its ends glued together.
Unavoidably, all cylindrical projections have an east-west stretching away from the equator by a factor equal to the secant of the latitude, compared with the scale at the equator.
www.bookrags.com /Map_projection   (3524 words)

  
 9.8 Map Projection   (Site not responding. Last check: )
A map projection is used project the rotated ellipse representing the earth's shape, to a two-dimensional plane.
The Polar stereo projection is a perspective projection, as shown in Figure 9.8.2, which projects the northern or southern hemisphere from a projection center at the opposite pole to a vertical plane tangent at the pole.
The Mercator projection, as shown in Figure 9.8.3, is a typical cylindrical projection with the equator tangent to the cylinder.
www.profc.udec.cl /~gabriel/tutoriales/rsnote/cp9/cp9-8.htm   (322 words)

  
 Understanding map projections
A map projection is a mathematical formula used to convert the three-dimensional surface of the earth to a two-dimensional surface, such as a map.
Deciding which map projection to use is determined largely by the specific properties of the projections, as well as what is being mapped and where it is on the earth.
For example, although the Mercator projection is often used for world mapping, it does not preclude it from being used for regions on or close to the equator with a predominately east-west extent.
mapshop.esri.com /help/concepts_projections.htm   (1978 words)

  
 Map Projection Essentials
Maps have widely varying graticule resolutions depending on their use and on the size of the area they are covering.
These are projections whose meridians and parallels curve toward the poles and maintain or decrease their distances from each other going from the center of the map to the edges.
But almost all projections are mathematical, not perspective, and since the shapes of their graticules were made for the equatorial aspect they often look unusual when displayed in oblique and polar aspects (azimuthal projections look normal in polar as well).
www.mapthematics.com /Essentials/Essentials.html   (3587 words)

  
 Map Projections -- 3DSoftware.com   (Site not responding. Last check: )
Cylindrical projections are used primarily for complete world maps, or for maps along narrow strips of a great circle arc, such as the Equator, a meridian, or an oblique great circle.
The Cassini map projection is the transverse aspect of the Plate Carree projection.
While cylindrical and conic projections are related to cylinders and cones wrapped around the globe, the azimuthal projections are formed onto a plane which is tangent to the globe.
www.3dsoftware.com /Cartography/USGS/MapProjections   (977 words)

  
 Map Projection - GIS Terminology - Geographic Information Systems - GIS Lounge   (Site not responding. Last check: )
A map projection is one of many methods used to represent the 3-dimensional surface of the earth or other round body on a 2-dimensional plane in cartography (mapmaking).
Flat maps have numerous advantages however; it is not practical to make large or even medium scale globes, it is easier to measure on a flat map, easy to carry around, and one can see the whole world at once.
Azimuthal projections touch the earth to a plane at one tangent point; angles from that tangent point are preserved, and distances from that point are computed by a function independent of the angle.
gislounge.com /glossary/bldefmapprojection.shtml   (1339 words)

  
 Map Projections Poster
A map projection is used to portray all or part of the round Earth on a flat surface.
Some projections are suited for mapping large areas that are mainly north-south in extent, others for large areas that are mainly east-west in extent, and still others for large areas that are oblique to the Equator.
Map projection—A map projection is a systematic representation of a round body such as the Earth or a flat (plane) surface.
erg.usgs.gov /isb/pubs/MapProjections/projections.html   (3453 words)

  
 VISTA: Maps & Projections: Map Projections
A map projection is the systematic arrangement of the earth’s (or generating sphere’s) surface onto a plane surface.
When projected from the center of the globe, the typical grid appearance for Conic projections shows parallels forming arcs of circles facing up in the Northern Hemisphere and down in the Southern Hemisphere; and meridians are either straight or curved and radiate outwards from the direction of the point of the cone.
Azimuthal projections are constructed from one of three perspectives where for each it is as if a light source were shown upon the globe and the arcs of the parallels and meridians were projected onto the flat, tangent, straight line surface.
acl.arts.usyd.edu.au /VISTA/20-maps&projections/map_projections.htm   (2241 words)

  
 Map Projections
Map projections can be grouped together in two basic ways; and a third characteristic, although it divides different way of using the same projection, is sometimes considered important enough that different versions of the same projection varying only in this characteristic are given different names.
In general, and this is true for the projections in the three basic aspects of cylindrical, conic, and azimuthal, scale going away from the center of a map increases for a conformal projection, and decreases for an equal-area projection.
Although some azimuthal projections can be drawn in other cases relatively easily, drawing most other map projections in a case different from the conventional one was very difficult before computers came along to draw maps for us.
www.hypermaths.org /quadibloc/maps/mapint.htm   (953 words)

  
 Winkel Tripel Map Projection   (Site not responding. Last check: )
The map displays a familiar "world political" map on one side and a new satellite image "mosaic" map of the physical world on the other.
The millennial school map giveaway project is the largest project of its kind for National Geographic.
Maps can be ordered for a special price of $39.95 for a limited time only by calling 1-800-368-2728 and requesting the "double-sided world map," product number M8I22001C.
www.hawaii.edu /hga/winkel.html   (281 words)

  
 Tabletop Projection :: Pen, Paper, & Pixel
The map is projected from the same laptop via monitor spanning.
For this map, the magic number was 36.7% of the original size.
We now have a visually appealing map to represent the adventuring environment, and the game-time consuming task of drawing a map is drastically reduced.
www.d20srd.org /extras/mapProjection.htm   (713 words)

  
 OMC: supported projections
Projection number five (Azimuthal Equidistant Projection) returns a circular plot of the entire world with the area of interest as the center, distances measured from there are true.
It is a useful projection for a global view of locations at various or identical distance from a given point (the map center).
The projection is neither equal area nor conformal, and much distortion is introduced near the edge of a hemisphere.
www.aquarius.geomar.de /omc/omc_project.html   (628 words)

  
 DIVERSOPHY.COM - using the Peters Map
Mercator's projection (created at a time when navigators were sailing on the oceans in wooden ships, powered by the wind, and navigating by the stars) was particularly useful because straight lines on his projection were lines of constant compass bearing.
The Peters projection is commonly used in contrast to a Mercator projection, and is visually engaging because it is so jarringly different.
The Van der Grinten projection was developed in 1904 and was the official projection of the National Geographic Society from 1922 to 1988.
www.diversophy.com /petersmap.htm   (1469 words)

  
 Data Standards - Projection   (Site not responding. Last check: )
A map projection is a mathematical model for conversion of locations from a three-dimensional earth surface to a two-dimensional map representation.
Projection types are based on the geometric form used in the transfer from the spherical earth to a flat surface.
For example, if a base map is in the Mercator projection and a data set of cities is in the Robinson projection, the cities will not be displayed in the correct location relative to the base map.
maic.jmu.edu /sic/standards/projection.htm   (162 words)

  
 The Atlas of Canada - Map Projections
In producing a map it is important to ensure a known relationship between true locations on the Earth and the corresponding points on the map.
If the area to be mapped is small (only a few square kilometres, as for example, a county, township or city), then the occurrence of error that results from projecting the curved surface of the Earth, to the flat surface of the map, is negligible.
A map projection is said to be equal-area or equivalent if it portrays areas over the entire map so that they retain the same proportional relationship to the areas on the Earth they represent.
atlas.nrcan.gc.ca /site/english/learningresources/carto_corner/map_projections.html   (2325 words)

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