You might also check out this paper:
http://www.foss4g.org/index.php/foss4g/2008/paper/view/226/157
It uses a "connect-buffer-simplify" approach.
Martin Davis wrote:
I think the ideas for the solution have already been posted on this
thread - you either need to use alpha shapes or one of the concave
hull algorithms. It sounded like pgrouting has an alpha shapes
implementation - that would probably be the easiest way forward.
Implementing the other algorithms would be non-trivial.
It might also help if you posted a picture of what you think the
desired output should be, for the sample data you posted.
Aleš Kecman wrote:
Hi!
I'm still struggling with this "concave hulls" and it seems I just
can't find the way how to do it. I'm sending a text file with some
longitude and latitude points of selected subarea from which I need
to get a concave polygon. There is only one polygon in attached text
file. In my database I have around 500 000 points from which I need
to form around 700 polygons. If there is a way to do it in PostGis I
would really appreciate any help. I also attached a jpg picture of my
convexhull polygon. Thanks!!!
Greets, Ales.
On Mon, Nov 24, 2008 at 12:13 PM, Mark Cave-Ayland
<[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
Aleš Kecman wrote:
Hi!
I'm new to Postgis and would really like to get some help on
getting a concave hull from an array of points.
For example:
I have an array of points - longitude and latitude of
buildings in particular area in the city. I already managed to
get a convex hull polygon from this array of points, but this
is not really helpful. What I'm trying to get is some kind of
concave hull polygon from an array of points, which I would
further like to use in Google Earth kml file.
Thanks.
Hi Aleš,
Does ST_Union() help you at all?
ATB,
Mark.
-- Mark Cave-Ayland
Sirius Corporation - The Open Source Experts
http://www.siriusit.co.uk
T: +44 870 608 0063
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