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<DIV dir=ltr align=left><FONT face="Trebuchet MS" size=2><SPAN
class=625394919-21062006>Hey Donal-</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face="Trebuchet MS" size=2><SPAN
class=625394919-21062006></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face="Trebuchet MS" size=2><SPAN
class=625394919-21062006>MapServer assumes a monitor resolution of 72 dpi by
default (so this is what the scale bar assumes by default). This is seldom
correct. The upshot is that the scale ratio (1:1000000) is seldom
correct. However, this doesn't really matter unless you advertise the
scale ratio and a client with a non 72 dpi monitor takes out a
ruler.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face="Trebuchet MS" size=2><SPAN
class=625394919-21062006></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face="Trebuchet MS" size=2><SPAN
class=625394919-21062006>There are two things that you can do if this bothers
you.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face="Trebuchet MS" size=2><SPAN
class=625394919-21062006>1) Guess at your client's resolution and modify the
scale bar's resolution property (myScaleBar.resolution =
96).</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face="Trebuchet MS" size=2><SPAN
class=625394919-21062006>2) Don't tell anybody what the scale ratio of your map
is, and rely on the scale bar for relating display distances to map
distances.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face="Trebuchet MS" size=2><SPAN
class=625394919-21062006></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face="Trebuchet MS" size=2><SPAN
class=625394919-21062006>Since people always toss around numbers like 1:250000
for map scales, it might be disappointing to hear that these numbers aren't
generally accurate for monitor displays (since there is not a reliable way
for the server to know the client's screen resolution ahead of time). This
is why I think it's better to rely on a scale bar than a numeric
scale.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face="Trebuchet MS" size=2><SPAN
class=625394919-21062006></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face="Trebuchet MS" size=2><SPAN
class=625394919-21062006>Tim</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face="Trebuchet MS" size=2><SPAN
class=625394919-21062006></SPAN></FONT> </DIV><BR>
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<FONT face=Tahoma size=2><B>From:</B> ka-map-users-bounces@lists.maptools.org
[mailto:ka-map-users-bounces@lists.maptools.org] <B>On Behalf Of </B>Donal
Regan<BR><B>Sent:</B> Wednesday, June 21, 2006 1:48 AM<BR><B>To:</B>
ka-Map-users@lists.maptools.org<BR><B>Subject:</B> [ka-Map-users] scalebar
question 1cm = 1km?<BR></FONT><BR></DIV>
<DIV></DIV>Hello all.<BR><BR>I am displaying a map that has amongst it's
scales 1:100000. I would expect my scalebar to show 1cm = 1km, i.e if I
physically measure the scalebar with a ruler, 1cm on the ruler would
correspond to 1km on the scalebar. However, I'm finding that 0.9cm = 1km ,
1.85cm = 2km up to 5.7cm = 6km.<BR><BR><BR> Is this just the way it
is or am I misunderstanding the way the scalebar should be
working?<BR><BR>Cheers,<BR><BR>Donal.<BR><BR>
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