FW: [STATSGRASS] Questions on calculating minimum dista ncebetween polygons and map attributes after m.in.e00
On Mon, 15 Dec 2003 White.Denis at epamail.epa.gov wrote:
> I am a new member of r-sig-geo and saw your message in
> the archives. I don't know whether you already had
> algorithms in mind, or received some responses on this,
> but two publications with algorithms are:
> Chin F, Wang CA. 1983. Optimal algorithms for the
> intersection and the minimum distance problems between
> planar polygons. IEEE Transactions on Computers,
> Vol C-32(12):1203-1207.
> Okabe A, Miller HJ. 1996. Exact computation methods for
> calculating distances between objects in a cartographic
> database. Cartography and Geographic Information Systems
> Vol 23(4):180-195.
Thanks for interesting references. In other email (I think offlist, but
repeating here to get further response), the idea of using OpenGIS
functions on a database was floated:
Distance(geometry,geometry) Return the cartesian distance between two
geometries in projected units.
It also has:
distance_spheroid(point, point, spheroid) Returns linear distance between
two lat/lon points given a particular spheroid. See the explanation of
spheroids given for length_spheroid(). Currently only implemented for
as a non-OpenGIS function. Kristian's question is about nation states, so
latlong is an issue, I believe. This makes it non-trivial, of course!
Any other ideas?
> > What I would like to do is to try to use an algorithm
> > to determine the shortest distance between points on
> > two states??? outer boundaries, with each state defined
> > either as a polygon or union of polygons.
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> R-sig-Geo at stat.math.ethz.ch
> https://www.stat.math.ethz.ch/mailman/listinfo/r-sig-geo >
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e-mail: Roger.Bivand at nhh.no
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Norwegian School of Economics
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