[OSRS-PROJ] Stereographic projection error

Gerald I. Evenden gerald.evenden at verizon.net
Thu Jul 3 10:14:44 EDT 2003

An email of yesterday, that I lost and can't refer to, indicated a
problem with the Stereographic projection in the Equitorial mode
(lat_0=0, default usage).

Indeed there was an error and both the X and Y coordinates were
miscaled by a factor of 2.0.

This is corrected in the next release of libproj4.  Because of the
importance of this correction, I will make a new release of libproj4
available this weekend.

The email also indicated usage of the Stereographic projection
that was in error: trying to project points that were at the
apodal point (opposite side of the earth).  Stereographic is
a member of the perspectives where the focus is at the opposite
side of the Earth from the origin and, like Mercator polar points,
points tend to infinity as you approach the focus.

Many thanks to the person who submitted the bug report.
Gerald I. Evenden <gerald.evenden at verizon.net>

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