A map projection is a way to move from form curved surface on a flat plane.
Projection map has general provisions, namely:
1.
Conform, which forms the area to be drawn according to the original form.
2.
Equivalent, which is broad areas or areas that should be drawn is
proportional to the actual same.
3.
Equidistant, which is described to be the right distance in comparison with
the state of the actual distance.
Projection map can be
divided into several types, namely:
1.
Projections based on field projection
a. Zenithal projection (azimuthal)
The projection field in the form of a flat, offensive ball at the poles,
the equator or in any place. This projection can be divided into:
1) Normal azimuth projection, ie the projection field
tangent to the pole.
2) Projection of the transverse azimuth, the
projection field perpendicular to the equator.
3) Oblique azimuthal projection, the projection
area of offending one of the places between the poles and the
equator.
b. Cylindrical projection
This projection uses a cylindrical projection and the offending areas of
the globe.
The use of cylindrical projection has several advantages, namely:
1) Can describe large areas.
2) Can describe the area around the equator.
3) The polar regions are depicted as a straight
line point.
4) More and more extensive regions closer to the
poles.
c.
Projection cone
Divided into three, namely:
1) normal or standard conical projection, ie
projection uses a cone with a tangent to the earth's sphere lies in a parallel
(standard parallel).
2) transverse conical projection, ie the
projection of the cone axis being perpendicular to the axis of the earth.
3) Projection of the oblique cone (oblique), the
projection of the axis of the cone to form a slash to the axis of the earth.
2.
Projection modification or composition (Arbitrary Projection)
This projection is more frequently used in daily life are obtained through
calculation. Here are some types of projection modification.
a. Bonne Projection (Equal Area)
This projection is a projection which is good
to describe the region that is located around the equator.
b. projection Moilweide
In this projection each part has the same size
to the area of the edge region of the projection. Getting closer to the
poles, the smaller the size change.
c. Sinusoidal projection
These projections illustrate the proper angle
and distance to the middle region of the meridian. As for the equatorial region
can be described with the appropriate area.
d. Mercator projection
Conformity is a normal cylindrical projection that depicts the earth in the
area of the cylinder axis coincides with the earth's sphere, then
as if the cylinder is opened into a flat plane. Mercator projection properties,
namely:
1) The projection is good and true for regions
close to the equator, but the distortion be larger when closer to the poles.
2) Interval is the same distance between the
meridian and the equator true vertical division Menrut scale.
3) The interval distance between the parallel is
not the same, farther away from the equator, the distance interval continues to
expand.
4) The projections are in conformity.
5) The poles can not be described because it is
located in an infinite positions.
e. Homolografik projection (Goode)
This projection is a projection error correction in Mollweide projection.
Better to describe the spread.
f.
Gall projection
The distinctive feature of this projection is owned by a different form at
latitudes approaching the poles.
3.
Projections based on the original properties are retained
a. Projected Equivalent
b. Conform projection
c. Equidistant projection
