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Topology -> Geography

posted by Satri on Tuesday March 27, @09:58AM        Permalink  Trackback URI  Slashdotthis  Diggthis  Del.icio.us
from the bring-topology-to-your-geography dept.

Anonymous Voxel writes "There are established tools that analyse geographic objects and extract the topological relationships, what polygon borders what polygon, etc. Is there anything that does the reverse? That is a tool that given a set of topological relationships, can build a simple geography that matches it? For example; I would describe the topological relationships as something like this;
region A connects to regions B, C & D
region B connects to regions A & E
region C connects to region A
and so on. And then the (hypothetical) tool would construct geometry that satisfies the above topological relationships, whilst also being reasonably pleasing to the eye. In this case five polygons or boxes, either bordering each other, or maybe connected by lines."

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The Technical Ramblings blog has two entries discussing what's best for OpenStreetMap, using simple features or topogical features for their geodata. Read the comments. From the second part: "More followup from the list: It seems that there is a reason (in addition to routing) for topological behavior: editing. [...] This one is more interesting to me, because I feel like moving topology to the client actually turns editing a topological operation — after which, grouping the edits in the API should be simple."

• Graph drawing algorithms

  (Score:2)

  by Satri (3) on Tuesday March 27, @10:51AM (#1355)
  ( http://alexandreleroux.blogspot.com/ | Last Journal: Friday March 17, @05:07PM )

  On the OSGeo-discuss mailing list [osgeo.org], a contributor pointed to the Graph drawing wikipedia page [wikipedia.org] for the algorithms.

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• Force-Directed Layout

  (Score:4, Interesting)

  by briancnorton (255) on Tuesday March 27, @09:13PM (#1356)

  Think of the topology as a series of attractive (or repulsive) forces. (gravity, springs, magnets, etc) Now think of your features outside of the realm of point/line/poly and think entity. (easiest to represent as a point) With very complex topology, a VERY interesting effect occurs. Your axis (axes?) are meaningless, but spatial proximity implies relationship, even absent a direct connection.

  My current Project utilizes a very complex version of this logic. Check out the prefuse toolkit. It's a free Java SDK with LOTS of great code. Also look at liveplasma.com. The concept is very powerful.

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  • Prefuse and Vizster

    (Score:3)

    by Satri (3) on Wednesday March 28, @09:35AM (#1357)
    ( http://alexandreleroux.blogspot.com/ | Last Journal: Friday March 17, @05:07PM )

    Are you involved with Prefuse? My interest in Prefuse [prefuse.org] started about two years ago, before the alpha release. I believe this app is full of potential :-) And so is Vizster [jheer.org]. I even recently tried Prefuse through Eclipse, but my complete lack of java-related knowledge and lack of free time makes me rather unable to do anything worthy with it yet. I'm dreaming of the day Prefuse/Vizster will go out of 'beta' and be able to reach the masses. This is very exciting open source software :-)

    [ Reply to This | Parent ]