Dear Tim Thanks for your reply. I'm one of the coaches of this thesis.
> 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 => Is this also accessible through Python (plugin)? > 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... In fact, the fuzziness attribute has to be somehow 'attached' to segments. In the use cases I know often there are some segments along the boundary which are not fuzzy but crisp on purpose. An example might be where a street touches the fuzzy feature. So since segments of a polygon can't be accessed from 'outside' one solution might be to have a "shadow" layer which consists of polylines. => Do you have another idea on how to implement such "line segment atttributes" in QGIS? Yours, S. 2010/9/27 Tim Sutton <[email protected]>: > 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 >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/qgis-developer > > > _______________________________________________ > Qgis-developer mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/qgis-developer > > _______________________________________________ Qgis-developer mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-developer
