[Qgis-developer] point displacement renderer plugin

Alex Mandel tech_dev at wildintellect.com
Sun Mar 14 17:25:17 EDT 2010

Andreas Neumann wrote:
>> Another use to this type of methodology I saw in use recently is when
>> working with line layers that are road networks. Sometimes you need
>> mulitple parrallel lines of differing colors for some segments. Think of
>> subway, bus or other transit maps where several lines share part of
>> their routes and you want to show them all together.
> right - but this is an entirely different problem than the
> point-displacement render for point symbols that simply places points on
> a circle around the original center point.
> What you describe above is more complex where you'd also want your
> bus-lines to have minimal intersections - a problem that is today
> typically still solved by human brains instead of computers ...
>> An alternative visual to the one you have that might also be useful
>> would be a clustering algorithm that combines overlapping or neighboring
>> points into one symbol that automatically scales in size based on the
>> number aggregated.
> right - but how would you display different attributes then? It would
> probably work for one attribute but would be more complicated for two or
> more attributes.
> In our case we want to display both language and sex (male/female).
> Combining that into one shape would be problematic.
> Quite some interesting problems though ...
> Andreas

For your use case I have seen point based pie charts before, yet another
way. Don't get me wrong I was just adding ideas for more tools in
addition to this one.

It's all quite complicated cartography.


More information about the Qgis-developer mailing list