Understanding Map Projections

PERSPECTIVE
Polar aspect—All meridians.
Equatorial aspect—The equator.
PROPERTIES
Shape
Minimally distorted near the center, increasing
toward the edge.
Area
Minimally distorted near the center; the area scale
then decreases to zero on the edge or horizon.
Direction
True directions from the point of tangency.
The central meridian is 0°, and the latitude of origin is 90° S.
DESCRIPTION
Also known as Vertical Near-Side Perspective or
Vertical Perspective.
This projection is similar to the Orthographic
projection in that its perspective is from space. In
this projection, the perspective point is not an
infinite distance away; instead, you can specify the
distance. The overall effect of this projection is that it
looks like a photograph taken vertically from a
satellite or space vehicle.
Distance
Radial scale decreases from true scale at the center to
zero on the projection edge. The scale perpendicular
to the radii decreases, but not as rapidly.
LIMITATIONS
The actual range depends on the distance from the
globe. In all cases, the range is less than 90 degrees
from the center.
USES AND APPLICATIONS
Used as an aesthetic presentation rather than for
technical applications.
PROJECTION METHOD
Planar perspective projection. The distance above
the earth is variable and must be specified before the
projection can be calculated. The greater the
distance, the more closely this projection resembles
the Orthographic projection. All aspects are circular
projections of an area less than a hemisphere.
POINT OF CONTACT
A single point anywhere on the globe.
LINEAR GRATICULES
All aspects—The central meridian of the projection.
Supported map projections• 75