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 <[EMAIL PROTECTED]>: > 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 > > International Institute for Geo-Information Science and Earth Observation > (ITC) > Chamber of Commerce: 410 27 560 > > E-mail disclaimer > The information in this e-mail, including any attachments, is intended for > the addressee only. If you are not the intended recipient, you are hereby > notified that any disclosure, copying, distribution or action in relation to > the content of this information is strictly prohibited. If you have received > this e-mail by mistake, please delete the message and any attachment and > inform the sender by return e-mail. ITC accepts no liability for any error or > omission in the message content or for damage of any kind that may arise as a > result of e-mail transmission. > _______________________________________________ > Qgis-user mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/qgis-user > _______________________________________________ Qgis-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-user
