Understanding Map Projections

STEREOGRAPHIC
PROPERTIES
Shape
Conformal. Local shapes are accurate.
Area
True scale at center with distortion increasing with
distance.
Direction
Directions are accurate from the center. Local angles
are accurate everywhere.
Distance
Scale increases with distance from the center.
The central meridian is 0°, and the latitude of origin is 90° S.
DESCRIPTION
This projection is conformal.
PROJECTION METHOD
Planar perspective projection, viewed from the point
on the globe opposite the point of tangency.
Stereographic projects points on a spheroid directly
to the plane. See Double Stereographic for a
different implementation.
LIMITATIONS
Normally limited to one hemisphere. Portions of the
outer hemisphere may be shown, but with rapidly
increasing distortion.
USES AND APPLICATIONS
The oblique aspect has been used to map circular
regions on the moon, Mars, and Mercury.
All meridians and parallels are shown as circular arcs
or straight lines. Graticular intersections are
90 degrees. In the equatorial aspect, the parallels
curve in opposite directions on either side of the
equator. In the oblique case, only the parallel with
the opposite sign to the central latitude is a straight
line; other parallels are concave toward the poles on
either side of the straight parallel.
POINT OF CONTACT
A single point anywhere on the globe.
LINEAR GRATICULES
Polar aspect—All meridians.
Equatorial aspect—The central meridian and the
equator.
Oblique aspect—Central meridian and parallel of
latitude with the opposite sign of the central latitude.
Supported map projections• 87