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Yes, the idea works, but the differences in hue are too small to be
useful in practice. And furthermore, they also show up for border
lines between adjoining polygons. I just want to highlight polygons
that completely overlap. I'm afraid I have to go the PostGIS/GEOS
way.<br>
<br>
Even o, would an XOR brush not be a nice addition to the STYLE
object? You could create all kinds of moiré fill patterns.<br>
<br>
<a class="moz-txt-link-freetext" href="http://www.google.nl/search?q=moire&hl=en&client=firefox-a&hs=lGh&tbo=u&rls=org.mozilla:en-GB:official&tbm=isch&source=univ&sa=X&ei=C1UCUez4C9KX0QXV9IDoDw&ved=0CFMQsAQ&biw=1600&bih=809">http://www.google.nl/search?q=moire&hl=en&client=firefox-a&hs=lGh&tbo=u&rls=org.mozilla:en-GB:official&tbm=isch&source=univ&sa=X&ei=C1UCUez4C9KX0QXV9IDoDw&ved=0CFMQsAQ&biw=1600&bih=809</a><br>
<br>
Jan<br>
<br>
On 1/24/2013 6:36 PM, Lime, Steve D (DNR) wrote:
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<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">You
could try drawing the features with the same base color but
with opacity set. The more times the same area is rendered
you’d get a different hue.<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-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Steve<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>
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<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">
<a class="moz-txt-link-abbreviated" href="mailto:mapserver-users-bounces@lists.osgeo.org">mapserver-users-bounces@lists.osgeo.org</a>
[<a class="moz-txt-link-freetext" href="mailto:mapserver-users-bounces@lists.osgeo.org">mailto:mapserver-users-bounces@lists.osgeo.org</a>]
<b>On Behalf Of </b>Jan Hartmann<br>
<b>Sent:</b> Thursday, January 24, 2013 11:00 AM<br>
<b>To:</b> Stephen Woodbridge<br>
<b>Cc:</b> <a class="moz-txt-link-abbreviated" href="mailto:mapserver-users@lists.osgeo.org">mapserver-users@lists.osgeo.org</a><br>
<b>Subject:</b> Re: [mapserver-users] Displaying
overlapping linestrings<o:p></o:p></span></p>
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</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On 01/24/2013 05:35 PM, Stephen
Woodbridge wrote:<o:p></o:p></p>
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<p class="MsoNormal">On 1/24/2013 11:13 AM, Jan Hartmann
wrote: <br>
<br>
<o:p></o:p></p>
<p class="MsoNormal">Does anyone know a trick to do this: <br>
<br>
I'm making geographical indexes for the map series in our
map library. <br>
Each map sheets is displayed as a polygonal linestring,
based on its <br>
corner coordinates. Lots of sheets have exactly the same
boundaries, so <br>
it's not clear where a polygon indicates just one map sheet
of several. <br>
It's easy, of course, to write a PostGIS query to return a
different <br>
color code when map boundaries exactly coincide, but I was
wondering <br>
whether something like that could be done by mapserver on
its own, like <br>
XOR-ing a line with what is already there. Any ideas? <o:p></o:p></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><br>
Hi Jan, <br>
<br>
For polygons you could use a small negative buffer to shrink
the polygon slightly. You can do this in postgis, and you
might be able to do it with mapserver if geos is compiled
in. See:
<br>
<br>
<a moz-do-not-send="true"
href="http://mapserver.org/development/rfc/ms-rfc-48.html">http://mapserver.org/development/rfc/ms-rfc-48.html</a>
<o:p></o:p></p>
</blockquote>
<p class="MsoNormal">No, that is not what I meant. I'm looking
for a trick for mapserver to color a linestring differently
when drawing over a linestring that it has already drawn in a
previous layer. In computer graphics you can do this by using
an XOR brush. Essentially, the screen frame buffer functions
as a sort of memory. I don not want to use PostGIS or GOS, too
complex. I doubt if this can be done by MapServer, but you
never know.<br>
<br>
Jan <o:p></o:p></p>
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