[vtkusers] Best fitting plane....

[Andres Barrera]

Thanks Malcom. I'm working on that.

       Andres


>
>OK, I think I see the problem. You aren't subtracting the centroid (ie. 
>mean
>values of x, y, z) from the points, so your covariance matrix is around the
>world origin (0,0,0) and not the centre of your points.
>
>HTH
>Malcolm
>
>----- Original Message -----
>From: "Andres Barrera" <andresba at hotmail.com>
>To: <malcolm at geovision.co.za>
>Sent: Monday, March 29, 2004 11:28 PM
>Subject: Re: [vtkusers] Best fitting plane....
>
>
> > Hello Malcom,
> >
> >     You told me to let you know if I had any problem..... well.. here I
>am!
> > ;)
> >
> >    I tryed to imlpement what you said, but I might be doing something
> > wrong... I attached the code ("Tests.cpp"), and a picture showing what I
>got
> > ("ViewSample.jpg"). May be it you can help me finding out the problem, 
>and
> > send me the demo code you offered me before for checking myself.
> >
> >     Once again, thant you very much for your time and your help.
> >
> >
> >          Andres
> >
> >
> >
> >
> > >
> > >Hi Andres
> > >
> > >Leo van Ruijven posted a response to a similar question some time back
> > >describing an eigenvector method.
> > >
> > >For every x,y,z calculate products xx,xy,xz,yy,yz,zz. Put sums of
>products
> > >in 3*3 matrix (ie. sxx,sxy,sxz;sxy,syy,syz;sxz,syz,szz) which now
> > >represents
> > >an ellipsoid bounding your point-set. Use vtkMath to calculate the
> > >eigenvectors and eigenvalues. The two largest values are in the plane,
>the
> > >smallest is normal to the plane.
> > >
> > >Let me know if you have any problems, I used this method recently and
>could
> > >dig up some demo code if you need it.
> > >
> > >HTH
> > >Malcolm
> > >
> > >----- Original Message -----
> > >From: "Andres Barrera" <andresba at hotmail.com>
> > >To: <vtkusers at vtk.org>
> > >Sent: Wednesday, March 24, 2004 7:06 PM
> > >Subject: [vtkusers] Best fitting plane....
> > >
> > >
> > > > Dear list,
> > > >
> > > > On Fri, 22 Mar 2002 16:39:55 +0100, Anner Adrian wrote:
> > > >
> > > > >>Hello,
> > > > >>
> > > > >>is in vtk a function to find the best fit for a plane with 
>n-points?
> > > > >>I have n-points and now I want place a vtkPlaneSource so that the
> > > > >>distance from the plane to the points is minimal.
> > > >
> > > > I need to solve a similar problem now, but I could find any answer 
>to
> > >that
> > > > in the User's List archives.
> > > >
> > > > Is there any defined way of calculating the best fitting plane 
>through
>a
> > > > series of points in vtk?
> > > >
> > > >    Thank you in advance
> > > >
> > > >          Andres
> >
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