[Qgis-developer] On the fly simplication of point layers

[Tim Sutton]

Hi


On Wed, Jan 22, 2014 at 2:47 PM, Tim Sutton <lists at linfiniti.com> wrote:

> Hi
>
>
> On Wed, Jan 22, 2014 at 1:23 PM, Martin Dobias <wonder.sk at gmail.com>wrote:
>
>> On Wed, Jan 22, 2014 at 4:33 PM, Tim Sutton <lists at linfiniti.com> 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
==============================================
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