does QGIS paint points to QPixMap and render the image or QGIS directly draws the point<div>like painter->drawCircle/point<br><br><div class="gmail_quote">On Tue, Sep 27, 2011 at 9:34 PM, Mohammed Rashad <span dir="ltr"><<a href="mailto:mohammedrashadkm@gmail.com">mohammedrashadkm@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><br><br><div class="gmail_quote"><div class="im">On Tue, Sep 27, 2011 at 8:25 PM, Marco Hugentobler <span dir="ltr"><<a href="mailto:marco.hugentobler@sourcepole.ch" target="_blank">marco.hugentobler@sourcepole.ch</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hi Mohammed<br>
<div><br>
> How came this time gap?<br>
<br>
</div>A possible reason could be the following:<br>
In QGIS, most point renderers do some caching of the point symbols as QImage.<br>
So in case you invoke a QPainter->drawCircle/drawRectangle etc. command for<br>
every point, it helps a lot do do the rasterisation only once.<br></blockquote></div><div>the point is not clear for me maybe because of my misunderstanding</div><div>will you please eloborate?? </div><div><div></div><div class="h5">
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
<br>
Regards,<br>
Marco<br>
<br>
<br>
Am Dienstag, 27. September 2011, 16.18:25 schrieb Mohammed Rashad:<br>
<div><div></div><div>> Hi All,<br>
> I am developing tiled vector rendering in OSSIM. I like the Qgis vector<br>
> rendering system<br>
><br>
> point.shp contains 9,99,999 points which are generated by grass for using<br>
> v.random and ~27MB in size<br>
> roads.shp contains 2,28,068 linestrings and is ~50MB in size<br>
><br>
> these point.shp and roads.shp data gets rendered in ~10 sec<br>
><br>
> When I read vector using ogr and parse feature and draw point/linestring my<br>
> application taking about 40 sec to render point.shp<br>
> and<br>
><br>
> I am using Qt4 with QPainter not QGraphicsView<br>
><br>
> How came this time gap?<br>
><br>
> i see Rtree and pal libs in src/core source code<br>
> Does they have any role in rendering?<br>
><br>
> Does QGIS Rendering uses threading?<br>
><br>
> How to get a minimal of QGIS code to hack it and build a new vector<br>
> rendering because I need it to make it tiled rendering vectors?<br>
><br>
> How to improve performance in rendering without qgis?<br>
> ---<br>
> Regards,<br>
> Mohammed Rashad K M<br>
> M.S. (By Research) student<br>
> Lab for Spatial Informatics<br>
> Department of CSE<br>
> International Institute of Information Technology<br>
> Hyderabad, India<br>
<br>
</div></div></blockquote></div></div></div><br><br clear="all"><div><br></div>-- <br><div><div></div><div class="h5"><div><font face="arial, helvetica, sans-serif">Regards,</font></div><font face="arial, helvetica, sans-serif"> Mohammed Rashad K M</font><div>
<font face="arial, helvetica, sans-serif"> M.S. (By Research) student<br>
Lab for Spatial Informatics<br> Department of CSE<br> International Institute of Information Technology</font></div><div><font face="arial, helvetica, sans-serif"> Hyderabad, India</font></div><br>
</div></div></blockquote></div><br><br clear="all"><div><br></div>-- <br><div><font face="arial, helvetica, sans-serif">Regards,</font></div><font face="arial, helvetica, sans-serif"> Mohammed Rashad K M</font><div><font face="arial, helvetica, sans-serif"> M.S. (By Research) student<br>
Lab for Spatial Informatics<br> Department of CSE<br> International Institute of Information Technology</font></div><div><font face="arial, helvetica, sans-serif"> Hyderabad, India</font></div><br>
</div>