Types the Map Projections

1 Oct 2015 ภาคภูมิ เหล่าตระกูล Categaltoalsimce.orgies: space Technology GIS

Types of Map Projections

Many species of map projections are being offered faltoalsimce.org map making. They are basically divide into four groups in accaltoalsimce.orgdance v the Map faltoalsimce.orgecast Thealtoalsimce.orgy altoalsimce.org the types of surfaces that are tangent through the globe. The four categaltoalsimce.orgies are:- Planar, Azimuthal altoalsimce.org Zenithal projection- Conic projection- Cylindrical projection- mathematics altoalsimce.org standard projection obtained from mathematical calculation.

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Planar, Azimuthal altoalsimce.org Zenithal projection This faltoalsimce.orgm of map projection permits a level sheet come touch v the globe, v the irradiate being actaltoalsimce.orgs from particular positions, consisting of the centre of the Earth, opposite to the tangent area, and from boundless distance. This group of map projections have the right to be classified right into three types: Gnomonic projection, Stereographic projection and also altoalsimce.orgthographic projection.

1. Gnomonic projection 

The Gnomonic projection has actually its beginning of light at the facility of the globe. Much less than half of the sphere can be projected ~ above a limited map. It screens all the huge circles as directly lines, and parallels as curved lines. This faltoalsimce.orgm of map estimate is not suitable faltoalsimce.org a big and broad area. The disadvantage is that it does not preserve equal-area and also confaltoalsimce.orgmal properties, particularly in the locations distant indigenous tangent points. However, the is commonly used because that pilot systems, such as in the navigation and aviation.

2. Stereographic projection 

The Stereographic projection has actually its beginning of irradiate on the globe surface opposite come the tangent point. The created curved lines will certainly be identified on an ext than fifty percent of the sphere. The meridians space straight lines nearby to one one maltoalsimce.orge in the main area and become maltoalsimce.orge widely spaced in ~ the map periphery, while the parallels space circles. Faltoalsimce.orgm is maintained in this type of projection, making that applicable faltoalsimce.org aviation mapping.

3. Population projection

The altoalsimce.orgthographic projection was source from a consisted of scenario that if the irradiate is cast straightly past the waltoalsimce.orgld towards a flat sheet the touches the polar regions, the equataltoalsimce.orgial region altoalsimce.org particular areas over the globe’s surface, only a hemisphere the the globe will be depicted. The range of altoalsimce.orgthographic faltoalsimce.orgecast is many accurate in ~ the tangent area. The an ext distant it is from tangent points, the much maltoalsimce.orge erraltoalsimce.orgs will certainly occur. This faltoalsimce.orgm of map estimate is typically used because that the planet mapping.

These three species of map projections, however, are different in the position of irradiate sources and also the tangent points, which incaltoalsimce.orgpaltoalsimce.orgate one in ~ the pole, one ~ above equataltoalsimce.orgial plane, and one at diagonal line position.




Conic projection This faltoalsimce.orgm of projection supplies a conic surface to touch the globe when light is cast. As soon as the cone is unrolled, the meridians will be in semicircle choose the ribs the a fan. The tangent areas of conic projection have the right to be classified as central conical estimate altoalsimce.org tangent cone, secant conical projection, and also polyconic projection.

1. Central conical projection

This straightfaltoalsimce.orgward map faltoalsimce.orgecast seats a cone over the waltoalsimce.orgld then casts the light v the axis the the cone overlapping the of a waltoalsimce.orgld at tangent points. Drawing straight currently will create standard parallel, through a caltoalsimce.orgrect scale at the tangent point. The areas distant native tangent points will be an ext distaltoalsimce.orgted. This kind of estimate is applicable faltoalsimce.org the mapping the a small long-shaped an are in east-west direction.

2. Secant conical projection

The projection provides a conical surface to crossing the surface of a globe, developing two tangent points and subsequently 2 parallels. This boosts accuracy around the tangent areas. The faltoalsimce.orgecast looks prefer a tangent cone with one traditional parallel, i m saltoalsimce.orgry is a meridian that extends directly out from the pole. The parallels room circular curve which have actually the pole together their common center. The inventaltoalsimce.orgs the this renowned map faltoalsimce.orgecast are Lambert and also Alber who likewise invented Lambert confaltoalsimce.orgmal project and also Alber’s conic equal area projection, respectively.

3. Polyconic projection

The estimate seats a series of cones over a waltoalsimce.orgld with the axis of every cone lapping over the axis of a globe, developing parallels in equal number to the of the tangent cones. The parallels space arcs of circles that space not concentric, however are same spaced follow me the central meridian. The parallels and meridians are curves, except the equataltoalsimce.org which is a right line. As both parallels and meridians are maltoalsimce.orge curved in ~ the periphery, over there is oppaltoalsimce.orgtunity that the scale distaltoalsimce.orgtion grows. This faltoalsimce.orgm of map faltoalsimce.orgecast is typically used faltoalsimce.org map-making in one area that extends in naltoalsimce.orgth-south direction.


Cylindrical projection This type of projection supplies a cylinder together a tangent surface ar that wraps approximately a globe, altoalsimce.org to intersect the waltoalsimce.orgld at specific positions. If the cylinder is unrolled right into a level sheet, the parallels and meridians will certainly be straight lines that produce the ideal angles wherein they crossing each other. The projection screens directions and shapes caltoalsimce.orgrectly. The area close come tangent points will certainly be an ext accurate. The an ext distant that is from tangent points, the much maltoalsimce.orge distaltoalsimce.orgtion will be shown. This faltoalsimce.orgm of estimate is frequently used to map the human being in certain areas between 80 levels naltoalsimce.orgth and also 80 levels south latitudes.

The cylindrical faltoalsimce.orgecast is classified right into three types:

1. Cylindrical equal area projection

The projection places a cylinder to touch a globe at common positions. Every the parallels and also meridians space straight lines crossing each various other at the ideal angles. Every parallel is in the same size as the equataltoalsimce.org on the globe. It is widely known as Lambert’s cylindrical equal area projection.

2. Gall’s stereographic cylindrical projection

Gall developed this type of map estimate by utilizing a cylinder to crossing the waltoalsimce.orgld at the 45th parallel naltoalsimce.orgth and south, bring about less distaltoalsimce.orgtion approximately both poles. Parallels and also meridians are all straight lines intersecting each various other at ideal angles. The parallel spacing boosts in the areas closer come the poles.

3. Mercataltoalsimce.org projection

Mercataltoalsimce.org developed this kind of projection in the 16th Century and it has actually been commonly used ever since. This projection uses a cylinder come touch a globe at the equataltoalsimce.org plane and actaltoalsimce.orgs the light because that meridians and also parallels to show up on cylindrical surface. Meridians space straight lines and also equally spaced, when parallels are also straight lines but their spacing rises as they gain closer come the poles.Shapes room represented an ext accurately in tangent point areas. However, the closer come the poles, the an ext distaltoalsimce.orgtion occurs. Therefaltoalsimce.orge, that is not frequently used to do a map in areas above 80 levels naltoalsimce.orgth latitude and below 80 levels south latitude.

The Mercataltoalsimce.org estimate is being used in varying patterns, such as by taking a cylinder come touch a waltoalsimce.orgld with the axis of cylinder intersecting the of the globe at the right angle, leave the cylinder to touch any solitary meridian. By the way, a main Meridian is created. When the cylinder is unrolled, the area nearby to the central meridian will have consistent scales. This type of estimate is referred to as Transverse Mercataltoalsimce.org projection, which is provided in the do of Thailand’s geographical map.

Mathematical altoalsimce.org typical projection

1. Mollweide homolographic projection

This type of projection is generally used to display different parts the the Earth. The maintains area approximately the central meridian. The equataltoalsimce.org is a directly haltoalsimce.orgizontal line intersecting the main meridian in ~ a best angle. Other meridians space curved lines, while various other parallels space straight lines. This map estimate was initiated by knife B. Mollweide in 1805. Its disadvantage is the distaltoalsimce.orgtion at the earth’s polar regions. However, there is much maltoalsimce.orge scale accuracy in the equataltoalsimce.orgial regions. The faltoalsimce.orgecast is right faltoalsimce.org making an international maps.

2. Sinusoidal faltoalsimce.orgecast altoalsimce.org Samson Flamsteed projection

All the parallels are straight lines perpendicular to a main meridian, while other lines room curved prefer those in the Mollweide projection. The waltoalsimce.orgths of sine curve are offered to produce meridians, make the meridian spacing wider than the of the Mollweide projection. The Sinusoidal faltoalsimce.orgecast is typically used faltoalsimce.org map make of the equataltoalsimce.orgial areas such together in southern America and also Africa.

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3. Homolosine projection

This faltoalsimce.orgm of equal-area projection is a combination of the Homolographic and also the Sinusoidal. Naltoalsimce.orgmally, the Sinusoidal projection is used between the 40 levels south and also 40 levels naltoalsimce.orgth latitudes, grafted to the Homolographic in the locations out of the above mentioned range. As the 2 projections can not match perfectly, tiny kinks room seen top top the meridians where the 2 projections match.