<html><body name="Mail Message Editor"><div><br></div><div>Not knowing anything about libproj4, I am surprised by this note. All projections of the complete globe are "multivariate". What does libproj4 do for other projections? Why would it not do something similar for ellipsoidal transverse Mercator?</div><div><br></div><div>Regards,</div><div>-- daan Strebe</div><div><br></div><br>On Aug 27, 2008, at 8:45:53 AM, "Gerald I. Evenden" <geraldi.evenden@gmail.com> wrote:<br><blockquote style="padding-left: 5px; margin-left: 5px; border-left-width: 2px; border-left-style: solid; border-left-color: blue; color: blue; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div style="width: 100%; "><div id="felix-mail-header-block" style="color: black; background-color: white; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: silver; padding-bottom: 1em; margin-bottom: 1em; width: 100%; "><table border="0" cellpadding="1" cellspacing="1" width="100%"><tbody><tr><td width="70px" style="font-family: 'Lucida Grande'; font-size: 8pt; color: gray; text-align: right; vertical-align: top; font-weight: bold; "><span>From:</span></td><td style="font-family: 'Lucida Grande'; font-size: 8pt; color: black; text-align: left; vertical-align: top; padding-left: 5px; "><span title=""Gerald I. Evenden" <geraldi.evenden@gmail.com>">"Gerald I. Evenden" <geraldi.evenden@gmail.com></span></td></tr><tr><td width="70px" style="font-family: 'Lucida Grande'; font-size: 8pt; color: gray; text-align: right; vertical-align: top; font-weight: bold; "><span>Subject:</span></td><td style="font-family: 'Lucida Grande'; font-size: 8pt; color: black; text-align: left; vertical-align: top; padding-left: 5px; "><span style="font-weight: bold; ">[Proj] Global Gauss-Kruger and libproj4---the final story</span></td></tr><tr><td width="70px" style="font-family: 'Lucida Grande'; font-size: 8pt; color: gray; text-align: right; vertical-align: top; font-weight: bold; "><span>Date:</span></td><td style="font-family: 'Lucida Grande'; font-size: 8pt; color: black; text-align: left; vertical-align: top; padding-left: 5px; "><span>August 27, 2008 8:45:53 AM PDT</span></td></tr><tr><td width="70px" style="font-family: 'Lucida Grande'; font-size: 8pt; color: gray; text-align: right; vertical-align: top; font-weight: bold; "><span>To:</span></td><td style="font-family: 'Lucida Grande'; font-size: 8pt; color: black; text-align: left; vertical-align: top; padding-left: 5px; "><span title=""PROJ.4 and general Projections Discussions" <proj@lists.maptools.org>">"PROJ.4 and general Projections Discussions" <proj@lists.maptools.org></span></td></tr></tbody></table></div><div id="felix-mail-content-block" style="color: black; background-color: white; width: 100%; "><div style="font-family: monospace; color: black; background-color: white; font-size: 8pt; ">Thanks to a reader I have a copy of the Lee-Thompson material for the<span class="Apple-converted-space"> </span><br>Transverse Mercator projection.<br><br>After perusing the material it is clear that no bivariate function operation<span class="Apple-converted-space"> </span><br>such as libproj4 can handle the general case of the global extent of the<span class="Apple-converted-space"> </span><br>Gauss-Kruger projection. This is because of the nature of the equator<span class="Apple-converted-space"> </span><br>graticule line and the fact that it branches into two parts as it approaches<span class="Apple-converted-space"> </span><br>90 degrees from the central meridian. That is, all points with 0 latitude<span class="Apple-converted-space"> </span><br>and with a delta longitude near 90 degrees will have *two* resultant<span class="Apple-converted-space"> </span><br>Cartesian coordinates---one for the northern hemisphere and one for the<span class="Apple-converted-space"> </span><br>southern hemisphere. Proj_fwd returns only one Cartesian point.<br><br>I had a suspicion that this was the case from viewing the "tombstone"<span class="Apple-converted-space"> </span><br>illustrations of TM referenced many weeks ago but had to wait to learn the<span class="Apple-converted-space"> </span><br>details of what was tranpiring.<br><br>So case closed.<br><br>Next.<br>--<span class="Apple-converted-space"> </span><br>The whole religious complexion of the modern world is due<br>to the absence from Jerusalem of a lunatic asylum.<br>-- Havelock Ellis (1859-1939) British psychologist<br>_______________________________________________<br>Proj mailing list<br>Proj@lists.maptools.org<br>http://lists.maptools.org/mailman/listinfo/proj<br><br></div></div></div></span></blockquote><br><div><br></div><div class="aol_ad_footer" id="uAE8D7400E9854A0A8C2B6A13FDFD8EFC"><FONT style="color: black; font: normal 10pt ARIAL, SAN-SERIF;"><HR style="MARGIN-TOP: 10px"><A title="http://mapquest.com/toolbar?ncid=mpqmap00050000000010" href="http://mapquest.com/toolbar?ncid=mpqmap00050000000010" target="_blank">Get the MapQuest Toolbar</A>. 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