Understanding Map Projections

MCBRYDE–THOMAS FLAT-POLAR QUARTIC
LIMITATIONS
Useful only as a world map.
USES AND APPLICATIONS
Thematic maps of the world.
The central meridian is 0°.
DESCRIPTION
This equal-area projection is primarily used for world
maps.
PROJECTION METHOD
A pseudocylindrical equal-area projection in which
all parallels are straight lines and all meridians,
except the straight central meridian, are equally
spaced, fourth-order (quartic) curves.
LINEAR GRATICULES
All parallels are unequally spaced straight lines that
are closer together at the poles. The poles are
straight lines one-third as long as the equator. The
central meridian is a straight line 0.45 times as long
as the equator.
PROPERTIES
Shape
Shapes are stretched north–south along the equator,
relative to the east–west dimension. This stretching
decreases to zero at 33°45' N and S at the central
meridian. Nearer the poles, features are compressed
in the north–south direction.
Area
Equal area.
Direction
Distorted except at the intersection of 33°45' N and S
and the central meridian.
Distance
Scale is distorted everywhere except along 33°45' N
and S.
Supported map projections• 69