<html><body name="Mail Message Editor"><div><br></div><div>(laugh!) Apologies for getting distracted. I meant to look it up but then forgot I hadn't. Thanks, Cliff.</div><div><br></div><div>Regards,</div><div>-- daan Strebe</div><div><br></div><br>On Jul 16, 2008, at 11:44:02 AM, "Clifford J Mugnier" <cjmce@lsu.edu> 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 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=""Clifford J Mugnier" <cjmce@lsu.edu>">"Clifford J Mugnier" <cjmce@lsu.edu></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; ">RE: [Proj] Re: Distance measured in Mercator projection</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>July 16, 2008 11:44:02 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><div id="idOWAReplyText71211" dir="ltr"><div dir="ltr"><font face="Times New Roman" color="#000000" size="2">I'd suggest something other than zero for the eccentricity of the WGS84 ellipsoid.š Say, e squared being 0.00669437999013, more or less ...</font></div><div dir="ltr"><font size="2"></font>š</div><div dir="ltr"><font size="2">Cliff Mugnier</font></div><div dir="ltr"><font size="2">LOUISIANA STATE UNIVERSITY</font></div></div><div dir="ltr"><br><hr tabindex="-1"><font face="Tahoma" size="2"><b>From:</b><span class="Apple-converted-space">š</span>proj-bounces@lists.maptools.org on behalf of strebe<br><b>Sent:</b><span class="Apple-converted-space">š</span>Wed 16-Jul-08 13:39<br><b>To:</b><span class="Apple-converted-space">š</span>PROJ.4 and general Projections Discussions<br><b>Subject:</b><span class="Apple-converted-space">š</span>[Proj] Re: Distance measured in Mercator projection<br></font><br></div><div><div><br></div><div>Shannon,</div><div><br></div><div>The scale factor in any direction at a given point on the ellipsoidal equatorial Mercator is:</div><div><br></div><div>h = –(1 - e^2 x sin^2 (phi)) / cos (phi)</div><div><br></div><div>where – is the square root of the expression; e is the eccentricity of the ellipsoid (0.0 for WGS84); ^2 means the square of the expression; and other symbols and semantics as given before.<br></div><div><br></div><div>Therefore you would multiply 1m x h to find the map distance of one meter at full scale. As you can see, this is the same as the original expression but just multiplied by the factor that adjusts for the eccentricity.</div><div><br></div><div>Don't hesitate to ask for clarification if you need it. Good luck.</div><div><br></div><div>Regards,</div><div>-- daan Strebe</div><div><br></div></div></div></div></span><br class="Apple-interchange-newline"></blockquote><br><div><br></div><div class="aol_ad_footer" id="u28D1095FC92A42ED9C0A5379D555B895"><FONT style="color: black; font: normal 10pt ARIAL, SAN-SERIF;"><HR style="MARGIN-TOP: 10px">The Famous, the Infamous, the Lame - in your browser. <A title="http://toolbar.aol.com/tmz/download.html?NCID=aolcmp00050000000014" href="http://toolbar.aol.com/tmz/download.html?NCID=aolcmp00050000000014" target="_blank">Get the TMZ Toolbar Now</A>!</FONT></div></body></html>