Conical Projection
In the conical case, we can visualize the Earth projected onto a tangent or secant cone, which is then cut lengthwise and laid flat.
Conical Projections
This projection is based on the concept of the 'piece of paper' being rolled into a cone shape and touching the Earth on a circular line.
In the Conical Projection the graticule is projected onto a cone tangent, or secant, to the globe along any small circle (usually a mid-latitude parallel).
Three well-known conical projections are the Lambert Conformal Conic projection, the Albers equal-area projection and the Polyconic projection.
The Lambert Conformal Conic projection in normal position is an example of a conic projection ...
Alberti's primary breakthrough was not to show the mathematics in terms of conical projections, as it actually appears to the eye.
The other main types, illustrated to the right, are cylindrical and conical projections. These three types of projections can be further modified by the way the 'paper' is oriented when it is inserted into the earth.
formulas for equidistant conical projection with one standard parallel (j0 , colatitude c0) are:
r = tan(c0) + tan(c - c0)
q = n l ...
There are also many other forms of projection which are not based on the cylinder, including conical projections (based on the model of a cone, placed with its vertex immediately above one of the poles) and entirely separate families of projections ...
Generally, the paper is either flat and placed tangent to the globe (a planar or azimuthal projection) or formed into a cone or cylinder and placed over the globe (cylindrical and conical projections).
 See also: Projection, Parallel, Map, Area, Surface
|
