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class=093234720-18052007>We're using OpenLayers as the map viewer.
MapServer will be running in CGI mode, either directly or as a WMS server.
So mapscript isn't part of the equation.</SPAN></FONT></DIV>
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class=093234720-18052007>I've never looked at the MapServer source, but
I'm wondering if allowing DATA statements to be placed in CLASS sections would
be a reasonable enhancement.</SPAN></FONT></DIV><BR>
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<FONT face=Tahoma size=2><B>From:</B> UMN MapServer Users List
[mailto:MAPSERVER-USERS@LISTS.UMN.EDU] <B>On Behalf Of </B>Guillaume
SUEUR<BR><B>Sent:</B> Friday, May 18, 2007 3:04 PM<BR><B>To:</B>
MAPSERVER-USERS@LISTS.UMN.EDU<BR><B>Subject:</B> [UMN_MAPSERVER-USERS]
RE : [UMN_MAPSERVER-USERS] Mutiple "DATA " lines in a single
layer?<BR></FONT><BR></DIV>
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<DIV dir=ltr><FONT face=Verdana color=#000000 size=2>as Stephen said, there is
only ONE data statement per layer. But, if you use mapscript, you can change
it dynamically depending on the scale for example</FONT></DIV>
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<DIV><FONT face=Arial size=2>Guillaume SUEUR</FONT></DIV>
<DIV><FONT face=Arial size=2>Géosignal - Groupe BVA</FONT></DIV>
<DIV><FONT face=Arial size=2>25bis Avenue Marcel Dassault</FONT></DIV>
<DIV><SPAN style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">BP
95836</SPAN></DIV>
<DIV><FONT face=Arial size=2>31505 Toulouse CEDEX 05</FONT></DIV>
<DIV><FONT face=Arial size=2>Tél : 05 61 17 47 17</FONT></DIV>
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size=2>---------------------------------------------</FONT></DIV>
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<FONT face=Tahoma size=2><B>De:</B> UMN MapServer Users List de la part de
Jeff Dege<BR><B>Date:</B> ven. 18/05/2007 20:32<BR><B>À:</B>
MAPSERVER-USERS@LISTS.UMN.EDU<BR><B>Objet :</B> [UMN_MAPSERVER-USERS] Mutiple
"DATA" lines in a single layer?<BR></FONT><BR></DIV>
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<P><FONT size=2>I'm starting to play around with using MapServer to serve maps
from a<BR>PostGIS database.<BR><BR>One of the features that MapServer has is
that you can define multiple<BR>classes within a single layer, so you can
change the way that the map<BR>looks when drawn at different
scales/resolutions.<BR><BR>Is there some way to define multiple data sources
within a single layer,<BR>so that I can change how that data is obtained at
different layers?<BR><BR>In particular, I'm wondering how to best take
advantage of PostGIS's<BR>simplify() function - which can be used to reduce
the number of points<BR>included in a geometry based on resolution. If
I'm drawing a map at a<BR>resolution where one pixel equals 2000 meters on the
ground, there is no<BR>advantage to sending the viewer a geometry defined with
points<BR>twenty-five meters apart.<BR><BR>The obvious way is to define
multiple layers, each enabled at certain<BR>scales, and to include the
resulution appropriate for those scales in<BR>the DATA keyword's sql
statement. But this requires that the layer be<BR>duplicated for each
scale range. Is there a way to enable different<BR>DATA sql statements
at different scales/resolutions in a single layer<BR>definition?<BR><BR>I
don't see the DATA keyword in the documentation for the CLASS
section.<BR>Which is where I'd expect it to be if I could do what I
want.<BR><BR>Is there a way of including a value calculated from the scale in
the SQL<BR>statement within the LAYER section?<BR><BR> DATA
"simplify(the_geom, 1.0/<scale>) from streets"<BR><BR>Or am I stuck with
using multiple layers?<BR><BR></FONT></P></DIV></BLOCKQUOTE></BODY></HTML>