[Qgis-user] proportional symbols

[G. Allegri]

Thanks Dr. Kobben for the support :-)
As I told in the trac ticket, that I opened about this, the area
should/could be calculated on the base of a classification as done for
the graduated colors. The criteria can be equal intervals, quantiles,
natural breaks, standard deviation, etc.


2008/10/29 Barend Kobben <kobben at itc.nl>:
> Proportional point symbols indeed ARE one of the most important cartographic
> map types. If this gets implemented well in QGIS I am all for it. But please
> take care to do it right then! One important thing to note:
> For most symbols (2d symbols like squares and circles, ect) it's NOT 'double
> population should mean double SIZE', its actually 'double population should
> mean double AREA of the symbol'. Ie.  1x1 mm square = 10 people , 10x10 mm
> square = 1000 people.
>
> I've attached some slides from a lecture I regularly give about that. If
> needed, I can provide further advise or additional references...
> [attachement was refused, I've put it on:
> http://kartoweb.itc.nl/fileshare/propPointSymbols.pdf
> ]
>
> yours
>
> --
> Barend Köbben
> International Institute for Geo-Information
> Sciences and Earth Observation (ITC)
> PO Box 6, 7500AA Enschede, The Netherlands
> +31 (0)53 4874253
>
>
>>
>> It seems to be a more common feature than I thought. Still I don't
>> understand the use if this (I think double size should mean double
>> population) but I guess I can live with the clutter.
>>
>> Goyo
>
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