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<DIV dir=ltr align=left><SPAN class=500545313-18082004><FONT face=Arial
color=#0000ff size=2>Jacob -</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=500545313-18082004><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=500545313-18082004><FONT face=Arial
color=#0000ff size=2>I don't think this is something MapServer should be
expected to do. I am assuming that you're using a "geographic" projection
for your output data - is that correct? If so, the width of one degree on
longitude depends on the *latitude* (not the longitude) and the width of
one degree of latitude is approximately constant. But on any given map the
scale (in meters) north/south is different from the scale east/west - there
isn't a single "correction" you can make to fix that. The scale is
constant in "degrees" but varies with the position AND ANGLE in
meters.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=500545313-18082004><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=500545313-18082004><FONT face=Arial
color=#0000ff size=2>If you need a map in which units can be measured in a scale
of meter, you should use a projected map. Otherwise you're just not going
to be able to do it accurately - with or without MapServer's
help.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=500545313-18082004><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=500545313-18082004> <FONT
face=Arial color=#0000ff size=2>- Ed</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=500545313-18082004><!-- Converted from text/plain format -->
<P><FONT size=2>Ed McNierney<BR>President and Chief Mapmaker<BR>TopoZone.com /
Maps a la carte, Inc.<BR>73 Princeton Street, Suite 305<BR>North Chelmsford,
MA 01863<BR>Phone: +1 978 251-4242 Fax: +1 978 251-1396
</FONT></P></SPAN></DIV><BR>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> UMN MapServer Users List
[mailto:MAPSERVER-USERS@LISTS.UMN.EDU] <B>On Behalf Of </B>Jacob
Delfos<BR><B>Sent:</B> Wednesday, August 18, 2004 2:31 AM<BR><B>To:</B>
MAPSERVER-USERS@LISTS.UMN.EDU<BR><B>Subject:</B> [UMN_MAPSERVER-USERS]
compensate scale for longitude<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV><FONT face=Arial size=2>Hi List,</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I've been working on getting my "print to scale"
code to work properly when working in latitude/longitude. I had a consistent
error, and now realize it's because mapserver seems to ignore the longitude
when converting from degrees to metres. I was wondering if that is something
that could be changed. My code actually did compensate for it, which is why my
scale (which is wrapped around the mapserver scale) did not match my
scalebarsize after printing. It's quite a simple compensation; it's just a
matter of taking the number which is currently calculated for the size of
a pixel, and multiplying it with the cosine of the longitude (I use the
longitude of the centre of the map). Of course the scale would not be the same
throughout the map if your extent is large, but it will be a lot closer. In
Perth the difference is around 15%. Where in the code should this be
changed?</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>regards,</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Jacob</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>JACOB DELFOS<BR>SPATIAL INFORMATION
ANALYST<BR>Maunsell Australia Pty Ltd<BR>629 Newcastle Street<BR>PO Box
81<BR>Leederville 6902<BR>Western Australia<BR>ABN 20 093 846 925</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>Tel + 61 8 9281
6185<BR>Fax + 61 8 9281 6297<BR><A
href="mailto:jacob.delfos@maunsell.com">jacob.delfos@maunsell.com</A></FONT></DIV></BODY></HTML>