[vtkusers] vtkMath::Matrix3x3ToQuaternion

[David Català]

Hi,
I use this function with rotation matrix but when I multiply
two rotation matrix and later I apply this function this
warning appears.

Anyway I have some doubts about results beacause I compare with MATLAB
and they are diferent in signs. I dont know if order is important in
this:

VTK::: 0.9987 0.000232 0.01153 0.487
MATLAB::: -0.00232 -0.0115 -0.487 0.9987

or

VTK::: -0.9987 0.000232 0.01153 0.487
MATLAB::: 0.00232 0.0115 0.487 0.9987

thanks,
David

-----Mensaje original-----
De: David Gobbi [mailto:dgobbi at imaging.robarts.ca]
Enviado el: jueves, 16 de diciembre de 2004 17:29
Para: David Català
CC: Mathieu Malaterre; vtkusers at vtk.org
Asunto: RE: [vtkusers] vtkMath::Matrix3x3ToQuaternion


Hi David, Mathieu,

Matrix3x3ToQuaternion() works best with a rotation matrix,
i.e. an orthogonal matrix, but it should be robust enough to
handle other matrices.  Obviously it would still fail if
it gets a zero matrix.

Could you send some examples of matrices that it fails on?

 - David


On Thu, 16 Dec 2004, [iso-8859-1] David Català wrote:

> Not always.
>
> Then when this message appears,
> Quaternions that I get with this function are incorrect?
>
> thanks,
> David
> -----Mensaje original-----
> De: vtkusers-bounces at vtk.org [mailto:vtkusers-bounces at vtk.org]En
> nombre
> de Mathieu Malaterre
> Enviado el: jueves, 16 de diciembre de 2004 17:06
> Para: David Català
> CC: vtkusers at vtk.org
> Asunto: Re: [vtkusers] vtkMath::Matrix3x3ToQuaternion
>
>
> David,
>
> 	Are you passing in a symmetric matrix ?
>
> http://public.kitware.com/pipermail/vtkusers/2001-August/056976.html
> [The Jacobi algorithm only works on a symmetric matrix.  If you are
> using Jacobi to do a general eigen analysis, that could explain why
> you
> are seeing this message.]
>
> HTH
> Mathieu
>
>
> David Català wrote:
> > Hi everyone,
> > I'm using
> > 	 vtkMath::Matrix3x3ToQuaternion(matriuRotacions,quaternions);
> >
> > I have this warning message:
> >        "vtkMath::Jacobi: Error extracting eigenfunctions");
> > 	vtkMath.cxx line640
> >
> > If I look the code:
> >   //// this is NEVER called
> >
> >   if ( i >= VTK_MAX_ROTATIONS )
> >     {
> >     vtkGenericWarningMacro(
> >        "vtkMath::Jacobi: Error extracting eigenfunctions");
> >     return 0;
> >     }
> > Why if never called ia have this message??
> >
> >
> > David Català Monter
> >
> > DataPixel
> > Parque Industrial Pallejà
> > Ronda Santa Eulalia,37, Nave 13
> > 08780 Pallejà
> > Barcelona(SPAIN)
> >
> > Phone: +34 93 663 30 43
> > Fax: +34 93 663 18 38
> > e-mail:david.catala at datapixel.com
> >
> >
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>
>
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