Hi Michael,
I am extremely sorry that I did not cc my message to the list last time.
Thanks for providing me with the link.
Well let me tell me you my problem in detail.
>From the pdf I found that the minimum distance centroid would be the closest
that I would want. How can I compute it. However it would be better if
something of the following is provided.
I have a set of points on the surface of earth. I want to calculate a
central point such that the distance from it to the given points is in
required proportion with the additional requirement that this point should
be inside the polygon obtained by joining the points.
It's easy to see that a such a requirement cannot be perfectly met. Let me
give you an analogy in the euclidean geometry rather than spherical
geometry.
Suppose I have 4 points in the Euclidean plane. I want to calculate a point
which is equidistant/distances in equal proportions to the 4 points. Now
this is not always possible because if I choose a circle to pass through 3
points, it's not necessary that the fourth point too lies on the circle.
(because 3 points uniquely define a circle.)
So then we can do a kind of multidimensional scaling. Such that we try to
find a point which satisfies the criterion as best as it can.
While this is challenging enough to calculate on a euclidean plane.
Spherical geometry makes things even worse!!
I hope I was able to explain myself. Please do ask me if I was not clear.
--
thanks and regards,
~Apurv Verma
B. Tech.(CSE)
IIT- Ropar
Mobile - 09256587545
On Mon, Jul 25, 2011 at 1:10 PM, Michael Bedward
<[email protected]>wrote:
> Hello,
>
> Please reply via the list.
>
> So what sort of centroid do you want ? There are many in common use
> (see http://user.gs.rmit.edu.au/rod/files/publications/MSIA_Centroid.pdf
> for a comparison of some).
>
> Or is it enough to have any point that is inside some polygon formed
> by the data points e.g. the convex hull ?
>
> Michael
>
>
> On 25 July 2011 16:58, Apurv Verma <[email protected]> wrote:
> > Yes it is a type of centroid calculation only.
> > Given a polygon on the surface of earth, I need to calculate its
> centroid.
> > Have a look at this page.
> > http://www.fmepedia.com/index.php/InsidePointReplacer
> >
> > thanks and regards,
> >
> > ~Apurv Verma
> > B. Tech.(CSE)
> > IIT- Ropar
> > Mobile - 09256587545
> >
> >
> >
> >
> >
> >
> > On Mon, Jul 25, 2011 at 10:37 AM, Michael Bedward
> > <[email protected]> wrote:
> >>
> >> Hello Apurv,
> >>
> >> > I am absolutely new to the geo tool library. In fact I want to use it
> >> > for a
> >> > specific purpose in the open source project "phyloGeoRef".
> >>
> >> Great to see taxonomy / biogeography making an appearance here :)
> >>
> >> > Here is the
> >> > functionality that I want.
> >>
> >> > Given a set of (lat,long) pairs on the globe. I have to calculate the
> >> > inside
> >> > point replacer for these set of nodes. Is there some function in Geo
> >> > Tools
> >> > that provides this functionality. If not, Is there any other method to
> >> > do it
> >> > ?
> >>
> >> Can you provide more detail about the required output. I'm not
> >> familiar with the term "inside point replacer" and Wikipedia doesn't
> >> seem to know it either. Is it a type of centroid calculation ?
> >>
> >> Michael
> >
> >
>
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