Hi
On Fri, Jan 24, 2014 at 1:12 AM, A Huarte <[email protected]> wrote: > Hi! > > About simplification (no clustering), I think that the If we discard > points based on the distance to the last fetched and rendered point ( > https://github.com/qgis/QGIS/blob/master/src/core/qgsfeatureiterator.cpp#L36) > it will be very effective to render big dense points layers. I have a GIS > application using this technique and it draws LAS files (> 30mb) "fast". > > I would like write a "point simplifier" in QGIS to validate results. > Do you agree ? > I think this would be great. Since you are doing a full scan of the dataset, you should be able to count how many points each aggregate point represents right? I was thinking we could pass that the the renderer as a 'virtual' attribute so that we can use it to e.g. scale the symbol size. +1 from me to implement this anyway as a new cluster renderer (or a patch the point displacement renderer if that seems workable). Regards Tim > > Alvaro > > ------------------------------ > *De:* Tim Sutton <[email protected]> > *Para:* Martin Dobias <[email protected]> > *CC:* qgis-developer <[email protected]>; " > [email protected]" <[email protected]> > *Enviado:* Jueves 23 de enero de 2014 23:16 > > *Asunto:* Re: [Qgis-developer] On the fly simplication of point layers > > Hi > > > On Wed, Jan 22, 2014 at 2:47 PM, Tim Sutton <[email protected]> wrote: > > Hi > > > On Wed, Jan 22, 2014 at 1:23 PM, Martin Dobias <[email protected]>wrote: > > On Wed, Jan 22, 2014 at 4:33 PM, Tim Sutton <[email protected]> wrote: > >> > >> Actually the point displacement renderer already does clustering, > >> though it lacks more options to customize how the clustered symbol > >> would look like. > >> > > > > Doesnt it do the reverse? i.e. when more than one point falls in the same > > place, it shifts them aside so they are all visible. If it can be made to > > produce a scaled symbol based on the number of underlying points that > would > > be cool.That would also be a good time to change its name to 'Custer or > > displace' or something. > > I think that was what the renderer did originally, but nowadays it > also groups points within configured distance. Unfortunately it always > tries to draw a circle around the clustered point with original > symbols. If we introduced few rendering options, it would be more > useful: > - draw just the clustered symbol for the whole group > - scale the clustered symbol depending on the number of points inside > > > Yeah that should do it! > > > I tested with a large point dataset (geonames ~3.5 million records). > Basically enabling the point displacement renderer on that layer kills (or > takes so long I killed it) QGIS. Since the essence of clustering is to > speed up rendering times and reduce visual clutter, I suspect simple tweaks > to the renderer would not be enough. > > Regards > > Tim > > > > Regards > > Tim > > > Cheers > Martin > > > > > -- > Tim Sutton - QGIS Project Steering Committee Member > ============================================== > Please do not email me off-list with technical > support questions. Using the lists will gain > more exposure for your issues and the knowledge > surrounding your issue will be shared with all. > > Irc: timlinux on #qgis at freenode.net > > ============================================== > > > > > -- > Tim Sutton - QGIS Project Steering Committee Member > ============================================== > Please do not email me off-list with technical > support questions. Using the lists will gain > more exposure for your issues and the knowledge > surrounding your issue will be shared with all. > > Irc: timlinux on #qgis at freenode.net > ============================================== > > _______________________________________________ > Qgis-developer mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/qgis-developer > > > -- Tim Sutton - QGIS Project Steering Committee Member ============================================== Please do not email me off-list with technical support questions. Using the lists will gain more exposure for your issues and the knowledge surrounding your issue will be shared with all. Irc: timlinux on #qgis at freenode.net ==============================================
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