Every map projection has some distortion. Wright formally presented equations in Can you pick the singularities. Lee, distinguished cartographer and senior officer at a national mapping agency in New Zealand, further generalized and improved the accuracy of methods for arbitrary conformal mapping.
If these lines are a parallel of latitude, as in conical projections, it is called a standard parallel. This cylinder is wrapped around the Earth, projected onto, and then unrolled.
Therefore, in geoidal projections that preserve such properties, the mapped graticule would deviate from a mapped ellipsoid's graticule.
Mercator Projection The Mercator Projection is probably the most popular projection that was ever designed. Indeed, stretching grows steadily towards the top and bottom of the map in the equatorial form, in higher latitudes; the poles would be actually placed infinitely far away.
Area distortion is evident near the boundary meridians but, uniquely, both projections are conformal at every point, even the poles. The Equal Area Projection on the left correctly shows the relative sizes of regions on the map.
Mercatorconic e. One way of describing a projection is first to project from the Earth's surface to a developable surface such as a cylinder or cone, and then to unroll the surface into a plane. An extra superimposed green graticule helps determining direction and distance from Campinas to every other point on Earth.
Some of the more common categories are: No map projection can preserve shapes of larger regions. Because each user should be sent only the minimum data to assemble his or her area of interest, equatorial cylindrical projections are almost ideally suited for tiling: Likewise, the captain of a nuclear submarine could use this projection to check which cities lie inside its destructive range.
It is often used to try to make models amenable to extension beyond curvature singularitiesfor example to permit description of the universe even before the big bang.
Hence other peer categories have been described in the literature, such as pseudoconic, pseudocylindrical, pseudoazimuthal, retroazimuthal, and polyconic. Selecting a model for a shape of the Earth involves choosing between the advantages and disadvantages of a sphere versus an ellipsoid.
Furthermore, it is often used in the construction of topographic and meteorological maps.
However, there are in most cases, one or more lines on a map along which scale is maintained correctly. Internet URLs are the best. One map projection might be used for large-scale data in a limited area, while another is used for a small-scale map of the world. The following diagram shows how three-dimensional features are compressed to fit onto a flat surface.
Why an equatorial cylindrical projection. An extremely simplified overview of the process which converts cartographic assets into mapped tiles deliverable to users. The geodesic may be plotted on a gnomonic map, and later transferred to a Mercator map and split in loxodromes piecewise.
Listed here after pseudocylindrical as generally similar to them in shape and purpose. Later, users are served tiles, commonly overlaid with dynamic data which is optional like markers and routeslocalized street and place names or frequently updated such as traffic conditions.
The ellipsoidal model is commonly used to construct topographic maps and for other large- and medium-scale maps that need to accurately depict the land surface.
On a pseudocylindrical map, any point further from the equator than some other point has a higher latitude than the other point, preserving north-south relationships.
Type of projection[ edit ] Cylindrical In standard presentation, these map regularly-spaced meridians to equally spaced vertical lines, and parallels to horizontal lines. One easy way to understand how map projections alter spatial properties is to visualize shining a light through the earth onto a surface, called the projection surface.
Submit Thank You for Your Contribution. Unfortunately, our editorial approach may not be able to accommodate all contributions. The east-west scale matches the north-south scale: Finding an oblique aspect which shows all major landmasses with no interruptions is a simple exercise for the spherical case — visually interesting but of little practical value; ellipsoidal versions for small regions pose a much more useful and difficult problem.
True-direction, or Azimuthal, projections maintain some of the great circle arcs, giving the directions or azimuths of all points on the map correctly with respect to the center. In recent years, this projection has been used frequently and broadly in the design and construction of topographic mappings, especially by Cartographers in the US and the UK.
Several approaches have been suggested, usually based on intermediate projection surfaces if successive conformal mappings are applied in sequence, the end result remains conformal and differing in details like the range of scale distortion; in general the constant scale along parallel lines of the spherical version is not retained.
Coast and Geodetic Survey, presented his conformal world map in two square hemispheres em In the first case Mercatorthe east-west scale always equals the north-south scale. In Rhumb Lines and Map Wars, Mark Monmonier offers an insightful, richly illustrated account of the controversies surrounding Flemish cartographer Gerard Mercator's douglasishere.com takes us back towhen Mercator announced a clever method of portraying the earth on a flat surface, creating the first projection to take into account the earth's roundness.
Online Conversions - advanced. Convert between pre-selected geodetic datums and projections using default input and output parameters. Use the basic online conversion to choose between pre-selected datums and projections using default input and output parameters. Use the vertical datum conversion to convert between New Zealand vertical datums - see instructions for carrying out height.
The only conformal cylindrical projection, Mercator's device was a boon to navigators from the 16th-century until the present, despite suffering from extreme area distortion near the poles: in order to keep shapes undistorted, Antarctica is enormously stretched, and Greenland is rendered about nine times larger than actual size.
Indeed. Spatial Reference List Home | Upload Your Own | List user-contributed references | List all references. The CF conventions generalize and extend the COARDS douglasishere.com extensions include metadata that provides a precise definition of each variable via specification of a standard name, describes the vertical locations corresponding to dimensionless vertical coordinate values, and provides the spatial coordinates of non-rectilinear gridded data.
List of map projections This list provides an overview of some of the significant or common map projections. Because Neither conformal nor equal-area, but a balance intended to reduce overall distortion.
Equidistant All distances from one (or two) points are correct. Other equidistant properties are mentioned in the notes.Conformal projection