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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I’ll create a ticket to do so. When MapServer was originally written there was a companion program for imagery (imgserv) that<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>was implemented using the Erdas Imagine C toolkit. I followed their lead at the time and it’s stuck…<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>“Would it make sense to add an option for MapServer to treat extents the same way as GDAL?” Sure, it’s called WMS…<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>Steve</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'> Jan Hartmann [mailto:j.l.h.hartmann@uva.nl] <br><b>Sent:</b> Thursday, February 17, 2011 9:18 AM<br><b>To:</b> Lime, Steve D (DNR)<br><b>Cc:</b> Mohamed Saâd HESSANE; mapserver-dev@lists.osgeo.org<br><b>Subject:</b> Re: [mapserver-dev] Implementation of the msCalculateScale<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Interesting. Could this be added to the documentation? It's important when you are scaling at pixel level. Would it make sense to add an option for MapServer to treat extents the same way as GDAL?<br><br>Jan<br><br>On 2011-02-17 16:07, Lime, Steve D (DNR) wrote: <o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>It’s due to how MapServer interprets extents. It uses a pixel-center model so you end up using width or height minus one in computations because</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>an extent is from the center of the UL pixel to the center of LR pixel (you lose the “one” from the outside) . I’ve attached a graphic I created some time</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>ago that illustrates the difference between a MapServer extent and the model GDAL and WMS use.</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Steve</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'> </span><o:p></o:p></p><div style='border:none;border-top:solid windowtext 1.0pt;padding:3.0pt 0in 0in 0in;border-color:rgb(181, 196, 223) -moz-use-text-color -moz-use-text-color'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> <a href="mailto:mapserver-dev-bounces@lists.osgeo.org">mapserver-dev-bounces@lists.osgeo.org</a> [<a href="mailto:mapserver-dev-bounces@lists.osgeo.org">mailto:mapserver-dev-bounces@lists.osgeo.org</a>] <b>On Behalf Of </b>Mohamed Saâd HESSANE<br><b>Sent:</b> Thursday, February 17, 2011 4:41 AM<br><b>To:</b> <a href="mailto:mapserver-dev@lists.osgeo.org">mapserver-dev@lists.osgeo.org</a><br><b>Subject:</b> [mapserver-dev] Implementation of the msCalculateScale</span><o:p></o:p></p></div><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal>Good morning everybody.<br>I don't understand how the msCalculateScale function in mapscale.c is implemented.<br>As far as I know, the scale is calculated from the relation : inches_in_screen / inches_in_reallity.<br>inches_in_screen : depend on the DPI and the width of the map;<br>inches_in_reality : depend on the map.extent, and the pixel size.<br>So why the "width-1" at the line 96? For me just "width" is more correct. Perhaps I'm wrong.<br>The branches 4.X have just "width" in their implementations (line 125).<br>So why the center pixel is removed from calculation?<o:p></o:p></p><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre>_______________________________________________<o:p></o:p></pre><pre>mapserver-dev mailing list<o:p></o:p></pre><pre><a href="mailto:mapserver-dev@lists.osgeo.org">mapserver-dev@lists.osgeo.org</a><o:p></o:p></pre><pre><a href="http://lists.osgeo.org/mailman/listinfo/mapserver-dev">http://lists.osgeo.org/mailman/listinfo/mapserver-dev</a><o:p></o:p></pre></div></body></html>