The Mercator projection is a cylindrical, conformal map projection in which meridians and parallels are straight lines that cross at 90-degree angles. Angular relationships are preserved. To preserve conformality, parallels are placed increasingly farther apart with increasing distance from the equator. This results in extreme distortion at high latitudes. Scale is true along the equator or along two parallels equidistant from the equator.
Despite its drawbacks, the Mercator projection is quite useful for navigation because rhumb lines (loxodromes), which show constant direction, are straight. The Mercator projection is also appropriate for conformal maps of equatorial regions.
The "Mercator" Projection has the following Parameters:
|
Parameter Name |
Parameter String |
Units |
|
Longitude of the Center of the Projection |
central_meridian |
|
|
Latitude of the Origin of the Projection |
latitude_of_origin |
|
|
Scale Factor |
scale_factor |
Double |
|
False Easting |
false_easting |
|
|
False Northing |
false_northing |
Using these parameters, there are two different variations of the Mercator projection that can be supported.
When using the first variation the Scale Factor must be a value other than 1. In this variation, the Latitude of True Scale value will be ignored.
When using the second variation the Scale Factor must be equal to 1, and will thus be ignored. The actual scaling factor will be calculated by using the value of the Latitude of True Scale parameter.