Hi On Wed, 2010-09-22 at 17:47 +0200, Annina Hirschi Wyss wrote: > Hello, > > I'm preparing my master's thesis on the subject of handling fuzzy objects > using the fuzzy logic, with the focus on geometries (not on the thematic > level). > I wanted to know, if there has already been a discussion about implementing > this in QGIS or in a plugin. >
As far as I know, no one is working on this or has discussed it. But its an interesting topic and it would be nice to see some real innocation happening in QGIS. > Showing the uncertainty of boundaries is needed in some cases of spatial > planning, when the "crisp" geometries are not yet defined. > > A possible use case could also be to draw a polygon with certain attributes, > then the border of the polygon "copied" to one or more oriented polyline > layers with special attributes (e. g. the distance of the uncertainty, to > which the fuzzy-function is applied). These polylines are linked by a foreign > key to the polygon-feature. This would certainly require the use of a > database, namely Postgre/PostGIS. > A polyline layer (linked to the polygon) can also be "crisp" e.g. if the > border is a street or a river. So it should be possible to combine crisp and > fuzzy segments for the same polygon. > Visualising this could result in a polygon with a sort of "thick pen-trace" > (the thickness corresponding to the distance-attribute of the polyline) > boundary, showing the uncertain band. The thickness corresponds to the > distance-attribute of the polyline. > > Another possible visualisation (sort of fuzzy buffers) is presented in the > following paper: http://www.geo3.nl/12%20fuzzy%20set%20theory.pdf (fig. 1b). > Right - one could probably apply blur effects and similar to lines to represent their fuzzyness - Qt4 already has some infrastructure for this kind of thing e.g. http://doc.qt.nokia.com/4.6/qgraphicsdropshadoweffect.html#details I'm not sure about using two separate layers as you describe above - it might be nicer to make fuzziness simply an attribute of the feature - though I guess it doesnt cope well for the scenario where individual segments of a feature have different fuzziness levels... > If there are developers interested in this, I would be glad to know, as my > own programming skills are rather basic. Look forward to seeing your proof of concepts! Regards Tim > > Thanks in advance > Annina_______________________________________________ > Qgis-developer mailing list > Qgis-developer@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/qgis-developer
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