https://issues.qgis.org/https://issues.qgis.org/favicon.ico2009-12-27T07:30:03ZQGIS Issue TrackingQGIS Application - Bug report #1963: "Ghost Lines" when using Anti-aliasing, polygons with shared boundaries, and no outline/QT::NoPenhttps://issues.qgis.org/issues/1963?journal_id=201132009-12-27T07:30:03ZPaolo Cavallinicavallini@faunalia.it
<ul></ul><p>Is this a QGIS, or a Qt bug?</p> QGIS Application - Bug report #1963: "Ghost Lines" when using Anti-aliasing, polygons with shared boundaries, and no outline/QT::NoPenhttps://issues.qgis.org/issues/1963?journal_id=201142009-12-30T07:19:22Zspringmeyer -dane@dbsgeo.com
<ul></ul><p>QT limitation which may benefit from workarounds in QGIS. I think this is an important ticket to have open for other users to see, or potentially as an FAQ only if we don't find an easy solution.</p> QGIS Application - Bug report #1963: "Ghost Lines" when using Anti-aliasing, polygons with shared boundaries, and no outline/QT::NoPenhttps://issues.qgis.org/issues/1963?journal_id=201152010-09-19T05:11:52ZPaolo Cavallinicavallini@faunalia.it
<ul></ul><p>Is this still true for current Qt and QGIS versions? Please confirm.</p> QGIS Application - Bug report #1963: "Ghost Lines" when using Anti-aliasing, polygons with shared boundaries, and no outline/QT::NoPenhttps://issues.qgis.org/issues/1963?journal_id=201162010-09-21T10:57:08ZJohn Tull
<ul></ul><p>This problem still exists in trunk with the most recent Qt release.</p> QGIS Application - Bug report #1963: "Ghost Lines" when using Anti-aliasing, polygons with shared boundaries, and no outline/QT::NoPenhttps://issues.qgis.org/issues/1963?journal_id=201172011-03-06T12:23:49ZTim Suttontim@linfiniti.com
<ul></ul><p>Hi</p>
<p>I did a little test using both:</p>
<pre>
QPainter::SmoothPixmapTransform
QPainter::HighQualityAntialiasing
</pre>
<p>In src/gui/qgsmapcanvasmap.cpp for <a class="wiki-page new" href="https://issues.qgis.org/projects/qgis/wiki/AntiAlias">AntiAlias</a> flags. Both choices did not resolve the issue for me. Using:</p>
<pre>
QGIS commit:e93c1841 (SVN r15735) Trunk
Qt 4.7
</pre> QGIS Application - Bug report #1963: "Ghost Lines" when using Anti-aliasing, polygons with shared boundaries, and no outline/QT::NoPenhttps://issues.qgis.org/issues/1963?journal_id=201182011-03-07T10:50:17Zspringmeyer -dane@dbsgeo.com
<ul></ul><p>We solved this sufficiently in Mapnik within the AGG renderer by allowing the user to control the AA gamma. A gamma of 0 is aliased while 1 is fully anti-aliased and setting gamma to around .6-.7 is able to remove the faint lines while keeping an AA-ish look with much more definition to edges (like coastlines) than can be achieved by the only other known workaround: overpainting with a thin line of the same color as the polygon fill. In short, we solved this by reducing the aggressiveness of the AA algorithm so that polygons are slightly dilated rather are fully AA or aliased.</p>
<p>So, I assume that QT will expose somewhere an equivalent gamma setting (or partial AA ability) - as QT's renderer is originally based on AGG (<a class="external" href="http://labs.qt.nokia.com/2009/12/18/qt-graphics-and-performance-the-raster-engine/">http://labs.qt.nokia.com/2009/12/18/qt-graphics-and-performance-the-raster-engine/</a>)</p> QGIS Application - Bug report #1963: "Ghost Lines" when using Anti-aliasing, polygons with shared boundaries, and no outline/QT::NoPenhttps://issues.qgis.org/issues/1963?journal_id=201192011-04-17T12:56:12ZTim Suttontim@linfiniti.com
<ul><li><strong>Status</strong> changed from <i>Open</i> to <i>Closed</i></li><li><strong>Resolution</strong> set to <i>wontfix</i></li></ul><p>Reading the the referenced article it seems they only were inspired by AGG and didnt directly use any source code from AGG in their implementation. It seems like Qt4 rendering engine does not expose any agg-like gamma options and there isnt really any reasonable work around we can come up with for this. I am going to close this ticket since the only way to resolve this issue currently is to disable AA rendering it would seem and there isnt anything else we can do to fix it.</p> QGIS Application - Bug report #1963: "Ghost Lines" when using Anti-aliasing, polygons with shared boundaries, and no outline/QT::NoPenhttps://issues.qgis.org/issues/1963?journal_id=201202011-04-17T16:30:33Zspringmeyer -dane@dbsgeo.com
<ul></ul><p>Okay.</p> QGIS Application - Bug report #1963: "Ghost Lines" when using Anti-aliasing, polygons with shared boundaries, and no outline/QT::NoPenhttps://issues.qgis.org/issues/1963?journal_id=389832013-02-26T00:24:15ZHenrik Uggla
<ul><li><strong>Assignee</strong> deleted (<del><i>nobody -</i></del>)</li><li><strong>Crashes QGIS or corrupts data</strong> set to <i>No</i></li><li><strong>Affected QGIS version</strong> set to <i>master</i></li><li><strong>Target version</strong> changed from <i>Version 1.7.0</i> to <i>Version 2.0.0</i></li><li><strong>Status</strong> changed from <i>Closed</i> to <i>Reopened</i></li><li><strong>File</strong> <a href="/attachments/download/5357/testlinux.pdf">testlinux.pdf</a> added</li></ul><p>Turning off "Make lines appear less jagged..." removes the thin lines on the screen but they still show when printing (see attached pdf). I can find no option for disabling anti-aliasing in the composer. Applies to both Windows7 and ubuntugis.</p>
<p>Note regarding attached pdf: The thin lines are displayed differently in different pdf-viewers.</p> QGIS Application - Bug report #1963: "Ghost Lines" when using Anti-aliasing, polygons with shared boundaries, and no outline/QT::NoPenhttps://issues.qgis.org/issues/1963?journal_id=534702014-06-28T05:37:49ZJürgen Fischerjef@norbit.de
<ul><li><strong>Target version</strong> changed from <i>Version 2.0.0</i> to <i>Future Release - Lower Priority</i></li></ul> QGIS Application - Bug report #1963: "Ghost Lines" when using Anti-aliasing, polygons with shared boundaries, and no outline/QT::NoPenhttps://issues.qgis.org/issues/1963?journal_id=753392017-03-27T07:22:19ZJohannes Kroeger
<ul></ul><p>I realised that <a class="issue tracker-1 status-5 priority-4 priority- closed" href="https://issues.qgis.org/issues/7241" title="Border of vector feature visible even with no pen border (Closed)">#7241</a> and <a class="issue tracker-1 status-5 priority-4 priority- closed" href="https://issues.qgis.org/issues/10166" title="Anti-aliasing leads to visible borders even if borders have "no pen" (Closed)">#10166</a> were duplicates of this and closed them accordingly.</p>
<p>Has anything happened in the past years or maybe, hopefully, in QT5 that allows this to be fixed? It would highly improve cartographic quality in some use cases.</p>
<p>If not, a "use fill color for stroke" checkbox would be nice, if that indeed is a workaround for this (as suggested in the duplicates). It could be a useful addition for other use cases as well maybe?</p> QGIS Application - Bug report #1963: "Ghost Lines" when using Anti-aliasing, polygons with shared boundaries, and no outline/QT::NoPenhttps://issues.qgis.org/issues/1963?journal_id=772812017-04-30T22:58:48ZGiovanni Manghigiovanni.manghi@gmail.com
<ul><li><strong>Pull Request or Patch supplied</strong> set to <i>No</i></li><li><strong>Regression?</strong> set to <i>No</i></li><li><strong>Easy fix?</strong> set to <i>No</i></li></ul> QGIS Application - Bug report #1963: "Ghost Lines" when using Anti-aliasing, polygons with shared boundaries, and no outline/QT::NoPenhttps://issues.qgis.org/issues/1963?journal_id=924022018-09-01T11:38:49ZJohannes Kroeger
<ul></ul><p>A workaround to this is:</p>
<p>Set the <strong>Stroke width</strong> to Hairline<br />Set the <strong>Stroke color</strong> to <code>@symbol_color</code> using <strong>Data defined override</strong></p>
<p>I forgot who shared this, either Nathan or Nyall. :)</p> QGIS Application - Bug report #1963: "Ghost Lines" when using Anti-aliasing, polygons with shared boundaries, and no outline/QT::NoPenhttps://issues.qgis.org/issues/1963?journal_id=924412018-09-02T15:19:56ZGiovanni Manghigiovanni.manghi@gmail.com
<ul><li><strong>Status</strong> changed from <i>Reopened</i> to <i>Closed</i></li><li><strong>Description</strong> updated (<a href="/journals/diff/92441?detail_id=81162" title="View differences">diff</a>)</li></ul><p>Johannes Kroeger wrote:</p>
<blockquote>
<p>A workaround to this is:</p>
<p>Set the <strong>Stroke width</strong> to Hairline<br />Set the <strong>Stroke color</strong> to <code>@symbol_color</code> using <strong>Data defined override</strong></p>
<p>I forgot who shared this, either Nathan or Nyall. :)</p>
</blockquote>
<p>is this in the docs? Can't find it.</p> QGIS Application - Bug report #1963: "Ghost Lines" when using Anti-aliasing, polygons with shared boundaries, and no outline/QT::NoPenhttps://issues.qgis.org/issues/1963?journal_id=936512018-09-30T13:55:52ZJohannes Kroeger
<ul></ul><p>I don't think so, it was either on IRC or Twitter.</p>
<p>This issue remains, please keep it opened. The workaround is just that, a workaround!</p>