Next: 6.2.2.1 Polar Stereographic Map
Up: 6.2 Azimuthal Projections
Previous: 6.2.1.2 Hemisphere map
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6.2.2 Stereographic Equal-Angle Projection (-Js -JS)
This is a conformal, azimuthal projection that dates back to the
Greeks. Its main use is for mapping the polar regions. In
the polar aspect all meridians are straight lines and parallels
are arcs of circles. While this is the most common use it is
possible to select any point as the center of projection. The
requirements are
- Longitude and latitude of the projection center.
- Scale as 1:xxxxx (true scale at pole), slat/1:xxxxx
(true scale at standard parallel slat), or radius/latitude where
radius is distance on map in inches from projection center to
a particular [possibly oblique] latitude (-Js), or simply map
width (-JS).
A default map scale factor of 0.9996 will be applied by default
(allthough you may change this with MAP_SCALE_FACTOR).
However, the setting is ignored when a standard
parallel has been specified since the scale is then implicitly given.
We will look at two different types of maps.
Subsections
Next: 6.2.2.1 Polar Stereographic Map
Up: 6.2 Azimuthal Projections
Previous: 6.2.1.2 Hemisphere map
  Contents
  Index
Paul Wessel
2004-10-01