<Aside> A nice implementation of alpha shapes with jts: http://www.mail-archive.com/[email protected]/msg01019.html </Aside>
2010/5/6 G. Allegri <[email protected]>: > Thanks Andrea for the links. Yes, I think the problem is similar, in > fact I was also looking for concave hull and alpha shapes algoithms, > but the only open solution I've found is from CGAL [1] and... it's too > complex to extract and reimplement in my context (database procedural > programming). > > IWe have implemented something very "rude": > > 1 - logically aggregate polyongs in clusters (given a certain distance) > 2 - buffer each polygon mantaining the shape (not the usual buffer, > which make rounded artifacts) > 3 - geometrical union > 4 - shrink the result (unbuffer) > > But I have the time for a long holiday waiting the end of the process :) > > [1] > http://www.cgal.org/Manual/last/doc_html/cgal_manual/Alpha_shapes_2/Chapter_main.html > > 2010/5/6 Andrea Aime <[email protected]>: >> G. Allegri ha scritto: >>> >>> I'm looking for an algorithm to do polygon cluster aggregation, >>> similar to the ArcInfo "Aggregate Polygon" [1]. >>> I know about GEOS "Cascaded Union", but I need two more features: >>> >>> 1 - clustering of polygons that fall within a a certain threshold >>> distance from each other >>> 2 - mantain orthogonality, i.e. the original angles/shapes >> >> I don't know of any such implementation, but it looks somewhat >> similar to the computation of a concave hull: >> >> http://ubicomp.algoritmi.uminho.pt/local/concavehull.html >> http://stackoverflow.com/questions/83593/is-there-an-efficient-algorithm-to-generate-a-2d-concave-hull >> >> Cheers >> Andrea >> >> -- >> Andrea Aime >> OpenGeo - http://opengeo.org >> Expert service straight from the developers. >> _______________________________________________ >> Discuss mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/discuss >> > _______________________________________________ Discuss mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/discuss
