5.5.3 Winkel Tripel Projection (–-Jr -–JR)

The Winkel Tripel projection, presented by Oswald Winkel in 1921, is a modified azimuthal projection that is neither conformal nor equal-area. Central meridian and equator are straight lines; other parallels and meridians are curved. The projection is obtained by averaging the coordinates of the Equidistant Cylindrical and Aitoff (not Hammer-Aitoff) projections. The poles map into straight lines 0.4 times the length of equator. To use it you must enter

$\bullet$

The central meridian

$\bullet$

Scale along equator in inch/degree or 1:xxxxx (-Jr), or map width (-–JR)

Centered on Greenwich, the example in Figure 5.28 was created by this command:

#!/bin/sh
#    $Id: GMT_winkel.sh,v 1.1 2001/03/21 04:10:21 pwessel Exp $
#

pscoast -R-180/180/-90/90 -JR0/4.5i -Bg30/g15 -Dc -A10000 -G128 -P > GMT_winkel.ps

Figure 5.28: World map using the Winkel Tripel projection