True projections are projections for which - in case the projection axis is identical with the Pole Axis - - the
*images of the longitudes are straight lines*, - the
*images of the latitudes either are straight lines or (concentric) circles*and *all lines*intersect each other*rectangularily*.
auxiliary surface which then will be un-winded onto the plane. Here we are speaking of the cylindrical and the conic projection. |
Rotation cylinders resp. rotation cones can be developable (auxiliary) surfaces. In case of the azimuthal projection the surface of the sphere is mapped onto the plane directly.In the mathematically view the conic projection is the most general case of true projections because of the cylinder and the plane are variations of the cone. A cylinder is a limiting form of a cone with an increasingly sharp point or apex. As the cone becomes flatter, its limit is a plane. Thus the true projections are also called conical projections.To each of these projections there exists equal-area, equidistant and conformal variants depending on the intended use of the current map. Take a choice and have a look. |

Principle of theConic Projection |
Principle of theAzimuthal Projection |
Principle of theCylindrical Projection | ||

forward to the untrue projections ... |