thanks Thomas,<br><br>well, actually, in my case this particular layer was created as line data, purely for cartographic purposes (it's not a polygon dataset being drawn as type LINE) so I thought the "duplicate edges" issue would not apply. <br>
<br>but I'll go back to the dashed symbol experiments to see if there are other ways to minimize the effect.<br><br>Tanya<br><br><br><div class="gmail_quote">On Wed, Apr 2, 2008 at 11:45 PM, thomas bonfort <<a href="mailto:thomas.bonfort@gmail.com">thomas.bonfort@gmail.com</a>> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">tanya,<br>
different symptoms but same "problem" here. even if your mapserver<br>
layer is of type "LINE", your counties data is polygonal data and<br>
therefore has duplicate edges, and mapserver will happilly draw these<br>
edges twice. depending on how the linestrings of the polygon are<br>
stored, the pattern of your dashes, the scale of your drawing, and a<br>
small dose of black magic, dashes will show up well or not ;)<br>
note that this isn't agg specific, the gd renderer has the same<br>
limitations when using dashes.<br>
<div class="Ih2E3d"><br>
--<br>
Thomas Bonfort<br>
<br>
Camptocamp France SAS<br>
Tel : +33 (0)4 79 26 57 97<br>
thomas dot bonfort at camptocamp dot com<br>
<a href="http://www.camptocamp.com" target="_blank">http://www.camptocamp.com</a><br>
<br>
</div><div><div></div><div class="Wj3C7c">On undefined, TC Haddad <<a href="mailto:tchaddad@gmail.com">tchaddad@gmail.com</a>> wrote:<br>
> hi thomas<br>
><br>
> my situation might be similar to Duarte: i'm also drawing counties, but in<br>
> my case I am drawing a line layer, not a polygon layer.<br>
><br>
> my preference was for drawing the lines with a dashed symbol, but at certain<br>
> scales (usually more zoomed out) the dashed lines will occasionally fail -<br>
> and would draw as solid. the pattern of failure seems really hard to predict<br>
> .... see the red circled area in the attached image.<br>
><br>
> this effect remained the same no matter how large the gap between my dashes<br>
> were, or how short my dash lengths (in this example basically 1 pixel dots,<br>
> and there is still a failure to solid line). any ideas on a work around? -<br>
> perhaps if I generalized the layer ?<br>
><br>
> tanya<br>
><br>
><br>
><br>
><br>
> On Wed, Apr 2, 2008 at 2:03 PM, thomas bonfort <<a href="mailto:thomas.bonfort@gmail.com">thomas.bonfort@gmail.com</a>><br>
> wrote:<br>
><br>
> > hi,<br>
> > it's one of the drawbacks of antialiasing in general, not a mapserver<br>
> > specific issue. an analogy could be found when drawing on paper with a<br>
> > felt-tip pen: if you pass twice on the same line the resulting effect<br>
> > is that the paper is twice as saturated in ink and the line appears<br>
> > thicker. this doesn't happen when drawing aliased bresenham lines as<br>
> > with the gd renderer, as multiple passes on a given line produces the<br>
> > same result as a single pass.<br>
> > hth,<br>
> > thomas<br>
> ><br>
> ><br>
> ><br>
> ><br>
> > On Wed, Apr 2, 2008 at 9:51 PM, DNC <<a href="mailto:dncarreira@gmail.com">dncarreira@gmail.com</a>> wrote:<br>
> > ><br>
> > > Thomas,<br>
> > ><br>
> > > I'm drawing administrative boundaries like counties. The data came from<br>
> a<br>
> > > polygon shapefile and converted to PostGIS. The boundaries are<br>
> topologically<br>
> > > correct in that shared boundaries are completely coincident and not<br>
> > > adjacent. I have never seen these polygons being drawn like you<br>
> describe. It<br>
> > > didn't even occurred to me that MapServer would have any difficulties<br>
> > > drawing this kind of data... How do you publish for instance the US<br>
> states?<br>
> > ><br>
> > > Thanks,<br>
> > > Duarte<br>
> > ><br>
> > ><br>
> > ><br>
> > ><br>
> > > tbonfort wrote:<br>
> > > ><br>
> > > > hi,<br>
> > > > you're probably drawing polygons with adjacent borders right?<br>
> > > > in this case, each line except the outer ones is drawn twice, and<br>
> thus<br>
> > > > its final width is larger than what is requested.<br>
> > > > I don't think there's much you can do about it except preprocess your<br>
> > > > data to transform it into a line layer with no duplicates.<br>
> > > ><br>
> > > > cheers,<br>
> > > > --<br>
> > > > Thomas Bonfort<br>
> > > ><br>
> > > > Camptocamp France SAS<br>
> > > > Tel : +33 (0)4 79 26 57 97<br>
> > > > thomas dot bonfort at camptocamp dot com<br>
> > > > <a href="http://www.camptocamp.com" target="_blank">http://www.camptocamp.com</a><br>
> > > ><br>
> > > > On Sat, Mar 29, 2008 at 1:22 PM, DNC <<a href="mailto:dncarreira@gmail.com">dncarreira@gmail.com</a>> wrote:<br>
> > > >><br>
> > > >> Hi.<br>
> > > >><br>
> > > >> I'm having trouble getting thin lines to draw. The thinnest line I<br>
> get<br>
> > > >> seems<br>
> > > >> to be 2 pixels wide at least. Using GD the lines are indeed 1<br>
> pixel.<br>
> > > >> Anyone<br>
> > > >> can point out why this happens?<br>
> > > >><br>
> > > >> Some sections from the map file:<br>
> > > >> OUTPUTFORMAT<br>
> > > >> NAME 'AGG_Q'<br>
> > > >> DRIVER AGG/PNG<br>
> > > >> MIMETYPE "image/png"<br>
> > > >> IMAGEMODE RGB<br>
> > > >> FORMATOPTION "QUANTIZE_FORCE=ON"<br>
> > > >> FORMATOPTION "QUANTIZE_DITHER=OFF"<br>
> > > >> FORMATOPTION "QUANTIZE_COLORS=256"<br>
> > > >> END<br>
> > > >> LAYER<br>
> > > >> NAME 'test'<br>
> > > >> GROUP "test group"<br>
> > > >> TYPE POLYGON<br>
> > > >> #MINSCALE 250000<br>
> > > >> CONNECTIONTYPE postgis<br>
> > > >> CONNECTION 'bla'<br>
> > > >> PROCESSING "CLOSE_CONNECTION=DEFER"<br>
> > > >> DATA 'the_geom from table using unique gid'<br>
> > > >> #FILTER ''<br>
> > > >> METADATA<br>
> > > >> 'wms_title' 'some layer'<br>
> > > >> "ows_abstract" "some text"<br>
> > > >> 'wms_srs' 'EPSG:27492'<br>
> > > >> "wms_opaque" "0"<br>
> > > >> "wms_group_title" "group title"<br>
> > > >> "wms_group_abstract" "group text"<br>
> > > >> END<br>
> > > >> STATUS ON<br>
> > > >> TRANSPARENCY 100<br>
> > > >> PROJECTION<br>
> > > >> 'init=epsg:27492'<br>
> > > >> END<br>
> > > >> EXTENT -23893.143277 -173568.018533 62541.864515 -70038.622014<br>
> > > >> MINSCALE 1<br>
> > > >> # MAXSCALE 100000<br>
> > > >> # data is queryable<br>
> > > >> DUMP TRUE<br>
> > > >> HEADER /ms_ogc_workshop/templates/rivers_query_header.html<br>
> > > >> TEMPLATE /ms_ogc_workshop/templates/rivers_query_body.html<br>
> > > >> # fuzziness for querying<br>
> > > >> TOLERANCE 5<br>
> > > >> CLASS<br>
> > > >> NAME 'outlines'<br>
> > > >> STYLE<br>
> > > >> WIDTH 1<br>
> > > >> OUTLINECOLOR 232 232 232<br>
> > > >> END<br>
> > > >> END<br>
> > > >> END<br>
> > > >><br>
> > > >> Regards,<br>
> > > >> Duarte<br>
> > > >> --<br>
> > > >> View this message in context:<br>
> > > >> <a href="http://www.nabble.com/agg-and-line-widths-tp16369480p16369480.html" target="_blank">http://www.nabble.com/agg-and-line-widths-tp16369480p16369480.html</a><br>
> > > >> Sent from the Mapserver - User mailing list archive at Nabble.com.<br>
> > > >><br>
> > > >> _______________________________________________<br>
> > > >> mapserver-users mailing list<br>
> > > >> <a href="mailto:mapserver-users@lists.osgeo.org">mapserver-users@lists.osgeo.org</a><br>
> > > >> <a href="http://lists.osgeo.org/mailman/listinfo/mapserver-users" target="_blank">http://lists.osgeo.org/mailman/listinfo/mapserver-users</a><br>
> > > >><br>
> > > > _______________________________________________<br>
> > > > mapserver-users mailing list<br>
> > > > <a href="mailto:mapserver-users@lists.osgeo.org">mapserver-users@lists.osgeo.org</a><br>
> > > > <a href="http://lists.osgeo.org/mailman/listinfo/mapserver-users" target="_blank">http://lists.osgeo.org/mailman/listinfo/mapserver-users</a><br>
> > > ><br>
> > > ><br>
> > ><br>
> > > --<br>
> > > View this message in context:<br>
> <a href="http://www.nabble.com/agg-and-line-widths-tp16369480p16450017.html" target="_blank">http://www.nabble.com/agg-and-line-widths-tp16369480p16450017.html</a><br>
> > ><br>
> > ><br>
> > > Sent from the Mapserver - User mailing list archive at Nabble.com.<br>
> > ><br>
> > > _______________________________________________<br>
> > > mapserver-users mailing list<br>
> > > <a href="mailto:mapserver-users@lists.osgeo.org">mapserver-users@lists.osgeo.org</a><br>
> > > <a href="http://lists.osgeo.org/mailman/listinfo/mapserver-users" target="_blank">http://lists.osgeo.org/mailman/listinfo/mapserver-users</a><br>
> > ><br>
> > _______________________________________________<br>
> > mapserver-users mailing list<br>
> > <a href="mailto:mapserver-users@lists.osgeo.org">mapserver-users@lists.osgeo.org</a><br>
> > <a href="http://lists.osgeo.org/mailman/listinfo/mapserver-users" target="_blank">http://lists.osgeo.org/mailman/listinfo/mapserver-users</a><br>
> ><br>
><br>
><br>
</div></div></blockquote></div><br>