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<p class=MsoNormal><font size=3 color=blue face=Arial><span style='font-size:
12.0pt;font-family:Arial;color:blue'>If I understand correctly, it is because
MapServer is based upon a cell size of center of pixel to center of pixel.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face=Arial><span style='font-size:
12.0pt;font-family:Arial;color:blue'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face=Arial><span style='font-size:
12.0pt;font-family:Arial;color:blue'>With 1 pixel you have nothing. With 2
pixels you have 1 cell.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face=Arial><span style='font-size:
12.0pt;font-family:Arial;color:blue'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face=Arial><span style='font-size:
12.0pt;font-family:Arial;color:blue'>Worth Lutz<o:p></o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
mapserver-dev-bounces@lists.osgeo.org
[mailto:mapserver-dev-bounces@lists.osgeo.org] <b><span style='font-weight:
bold'>On Behalf Of </span></b>Martin Kofahl<br>
<b><span style='font-weight:bold'>Sent:</span></b> Wednesday, April 10, 2013
2:40 PM<br>
<b><span style='font-weight:bold'>To:</span></b> MapServer Dev Mailing List<br>
<b><span style='font-weight:bold'>Subject:</span></b> [mapserver-dev] WMS
exception for requests width height=1</span></font><o:p></o:p></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Hello,<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>currently, I see wms clients (qgis, arcgis 10) doing getmap requests
with height=1. MapServer (6.2) throws an exception: <o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>msDrawMap(): Image handling error. Unable to initialize image.<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>msCalculateScale(): General error message. Invalid image extent,
minx=nan, miny=nan, maxx=nan, maxy=nan.<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>The reason is in msAdjustExtent(), where the cell size is calculated
using MS_CELLSIZE(miny,maxy,height), defined as ((max - min)/(d-1)).
Formally, I don't see any reasons against 1 pixel requests. What are
the reasons for "d-1"?<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Martin<o:p></o:p></span></font></p>
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<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'
color="#000000"><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>No virus found in this message.<br>
Checked by AVG - <a href="http://www.avg.com">www.avg.com</a><br>
Version: 2013.0.3272 / Virus Database: 3162/6236 - Release Date: 04/10/13<o:p></o:p></span></font></p>
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