Understanding Map Projections
Understanding Map Projections
Understanding Map Projections
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EQUIRECTANGULAR<br />
Area<br />
Distortion increases as the distance from the<br />
standard parallels increases.<br />
Direction<br />
North, south, east, and west directions are accurate.<br />
General directions are distorted, except locally along<br />
the standard parallels.<br />
The central meridian is 149° W.<br />
DESCRIPTION<br />
Also known as Simple Cylindrical, Equidistant<br />
Cylindrical, Rectangular, or Plate Carrée (if the<br />
standard parallel is the equator).<br />
This projection is very simple to construct because it<br />
forms a grid of equal rectangles. Because of its<br />
simple calculations, its usage was more common in<br />
the past. In this projection, the polar regions are less<br />
distorted in scale and area than they are in the<br />
Mercator projection.<br />
PROJECTION METHOD<br />
This simple cylindrical projection converts the globe<br />
into a Cartesian grid. Each rectangular grid cell has<br />
the same size, shape, and area. All the graticular<br />
intersections are 90 degrees. The central parallel may<br />
be any line, but the traditional Plate Carrée<br />
projection uses the equator. When the equator is<br />
used, the grid cells are perfect squares, but if any<br />
other parallel is used, the grids become rectangular.<br />
In this projection, the poles are represented as<br />
straight lines across the top and bottom of the grid.<br />
Distance<br />
The scale is correct along the meridians and the<br />
standard parallels.<br />
LIMITATIONS<br />
Noticeable distortion of all properties away from<br />
standard parallels.<br />
USES AND APPLICATIONS<br />
Best used for city maps or other small areas with<br />
map scales large enough to reduce the obvious<br />
distortion.<br />
Used for simple portrayals of the world or regions<br />
with minimal geographic data. This makes the<br />
projection useful for index maps.<br />
LINES OF CONTACT<br />
Tangent at the equator or secant at two parallels<br />
symmetrical around the equator.<br />
LINEAR GRATICULES<br />
All meridians and all parallels.<br />
PROPERTIES<br />
Shape<br />
Distortion increases as the distance from the<br />
standard parallels increases.<br />
Supported map projections• 55