On Mar 26, 2010, at 1:01 PM, Kurt Schwehr wrote: > I am a little confused with the convex hull functionality. Can someone set > me straight? > > > In [29]: type(ch) > Out[29]: <class 'shapely.geometry.polygon.Polygon'> > > In [30]: ch.wkt > Out[30]: 'POLYGON ((-0.5000000000000000 0.5000000000000000, > -1.5000000000000000 1.2000000000000000, -1.0000000000000000 > 1.0000000000000000, -0.5000000000000000 0.5000000000000000))' > > In [31]: ch.boundary > Out[31]: <shapely.geometry.linestring.LineString object at 0x13c0a10> > > In [32]: ch.boundary.wkt > Out[32]: 'LINESTRING (-0.5000000000000000 0.5000000000000000, > -1.5000000000000000 1.2000000000000000, -1.0000000000000000 > 1.0000000000000000, -0.5000000000000000 0.5000000000000000)' > > In [33]: ch.boundary.boundary > Out[33]: <shapely.geometry.multipoint.MultiPoint object at 0x13c0eb0> > > In [34]: ch.boundary.boundary.wkt > Out[34]: 'MULTIPOINT EMPTY' > > Here is where I thought I would have a multipoint with my points. I thought > it would take me one more level of bounary call to get to empty. Basically, > I want to build a convex hull of 10M points... I was thinking that it would > be way more efficient to add each point and compute a new convex hull. What > is the best way to attack something like this?
You want http://www.cs.unc.edu/~isenburg/lastools/download/lasboundary_README.txt It can give you the convex or *concave* hull(s) of varying tightnesses. This is not a job for GEOS. Howard _______________________________________________ Community mailing list [email protected] http://lists.gispython.org/mailman/listinfo/community
