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[ai-geostats] polygon changes

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  • Colin Robertson
    Dear List, Do any of you have experience/advice on spatiotemporal analysis of polygon data? I ve read about Sadahiro s methods
    Message 1 of 3 , Oct 28, 2005
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      Dear List,

       

      Do any of you have experience/advice on spatiotemporal analysis of polygon data?  I’ve read about Sadahiro’s methods (http://okabe.t.u-tokyo.ac.jp/okabelab/sada/docs/pdf/CSIS%20DP25.pdf ) on the subject and his ideas look promising to me, but I have not seen them implemented anywhere, nor have I seen anything comparable.  Has anyone have experience with these or other methods for analyzing changes in polygons over time?

       

      Thanks,

       

       

      Colin Robertson

      MSc Candidate

      Dept of Geography

      University of Victoria

       

      (250) 885-8065

       

    • Gerald van den Boogaart
      Dear Mr. Robertson, ... To me your question reads like: Did anybody of you at any time considered time in vektor GIS. And clearly one can lecture hours on
      Message 2 of 3 , Nov 1, 2005
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        Dear Mr. Robertson,

        > Do any of you have experience/advice on spatiotemporal analysis of
        > polygon data?
        To me your question reads like: Did anybody of you at any time considered time
        in vektor GIS. And clearly one can lecture hours on that, while "real world"
        GIS Systems typically don't support that properly. However to give any sort
        of advice one needs a more specific question:

        How do your polygones vary?
        What do they represent?
        Do they overlap in space / in time / in spacetime?
        Are they polygons by nature or just areas approximated by polygons.
        What are the questions, you would like to ask your data?
        Do you have a polygon process consisting of many polygons or do you observe
        one individual polygon changing over time.
        Do your polygons change smoothly or discontinuesly.
        Are the polygons individuals or perculations?
        Do they form a coverage (i.e. is everything occupied)?
        Is there a map of relevant additional covariates?
        Is their any sort of representatitivty in the dataset?
        What is your personal background (no need of writing well known things to you)
        Are you writing a thesis on the theory of analysing polygons or do you work on
        a specific problem.

        Best regards,
        Gerald v.d. Boogaart



        Am Samstag, 29. Oktober 2005 02:12 schrieben Sie:
        > Dear List,
        >
        >
        >
        > Do any of you have experience/advice on spatiotemporal analysis of
        > polygon data? I've read about Sadahiro's methods
        > (http://okabe.t.u-tokyo.ac.jp/okabelab/sada/docs/pdf/CSIS%20DP25.pdf )
        > on the subject and his ideas look promising to me, but I have not seen
        > them implemented anywhere, nor have I seen anything comparable. Has
        > anyone have experience with these or other methods for analyzing changes
        > in polygons over time?
        >
        >
        >
        > Thanks,
        >
        >
        >
        >
        >
        > Colin Robertson
        >
        > MSc Candidate
        >
        > Dept of Geography
        >
        > University of Victoria
        >
        >
        >
        > (250) 885-8065
      • Colin Robertson
        Dear Mr. Boogaart, Thanks for your response and I ll see if I can be clearer in my question. My interest is in detecting and characterizing changes in polygons
        Message 3 of 3 , Nov 1, 2005
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          Dear Mr. Boogaart,

          Thanks for your response and I'll see if I can be clearer in my question.
          My interest is in detecting and characterizing changes in polygons between
          T1 and T2. So essentially, comparing two polygon datasets. I think it's a
          little narrower than space and time in Vector GIS, as there are numerous
          methods available for point data, and while one way is to use polygon
          centroids with spatial information attached as attributes, I feel this does
          not effectively capture the complexity of the polygon data (ie boundary
          complexity, orientation, proximity to other features etc).

          So with two polygon datasets which are derived from peak values in an
          intensity surface (moving infestation), some polygons in T1 will intersect
          polygons in T2, some will not. The polygons therefore vary in space and in
          time. So my concern is, where there is intersection, can all of a polygon
          in T2 be considered to have come from the intersecting polygon in T1? Is
          there consistent shape complexity between both? Where there is no
          intersection, but proximity (to some threshold), can a relationship between
          T1 and T2 be established? More importantly, what spatial relationships
          (beyond spatial intersection) can be detected? How can I detect shrinking,
          expanding, moving, coalescing? Much information can be derived from
          visually looking at polygons in T1 and T2, but I am hoping to find a method
          to characterize / detect the change more formally.

          I hope this clears up my original post. As far as my background goes, I'm
          just starting a graduate thesis, and have completed a bachelors(geography)
          and advanced diploma(GIS). So I have much to learn about spatiotemporal
          analysis.

          Thanks for your interest,

          Colin

          -----Original Message-----
          From: Gerald van den Boogaart [mailto:boogaart@...]
          Sent: Tuesday, November 01, 2005 4:30 AM
          To: Colin Robertson
          Cc: 'AI Geostats mailing list'
          Subject: Re: [ai-geostats] polygon changes

          Dear Mr. Robertson,

          > Do any of you have experience/advice on spatiotemporal analysis of
          > polygon data?
          To me your question reads like: Did anybody of you at any time considered
          time
          in vektor GIS. And clearly one can lecture hours on that, while "real world"

          GIS Systems typically don't support that properly. However to give any sort
          of advice one needs a more specific question:

          How do your polygones vary?
          What do they represent?
          Do they overlap in space / in time / in spacetime?
          Are they polygons by nature or just areas approximated by polygons.
          What are the questions, you would like to ask your data?
          Do you have a polygon process consisting of many polygons or do you observe
          one individual polygon changing over time.
          Do your polygons change smoothly or discontinuesly.
          Are the polygons individuals or perculations?
          Do they form a coverage (i.e. is everything occupied)?
          Is there a map of relevant additional covariates?
          Is their any sort of representatitivty in the dataset?
          What is your personal background (no need of writing well known things to
          you)
          Are you writing a thesis on the theory of analysing polygons or do you work
          on
          a specific problem.

          Best regards,
          Gerald v.d. Boogaart



          Am Samstag, 29. Oktober 2005 02:12 schrieben Sie:
          > Dear List,
          >
          >
          >
          > Do any of you have experience/advice on spatiotemporal analysis of
          > polygon data? I've read about Sadahiro's methods
          > (http://okabe.t.u-tokyo.ac.jp/okabelab/sada/docs/pdf/CSIS%20DP25.pdf )
          > on the subject and his ideas look promising to me, but I have not seen
          > them implemented anywhere, nor have I seen anything comparable. Has
          > anyone have experience with these or other methods for analyzing changes
          > in polygons over time?
          >
          >
          >
          > Thanks,
          >
          >
          >
          >
          >
          > Colin Robertson
          >
          > MSc Candidate
          >
          > Dept of Geography
          >
          > University of Victoria
          >
          >
          >
          > (250) 885-8065
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