[vtkusers] vtkTransform::GetOrientation()

[George Kamucha]

Hello Marco,

Your hint has really been helpful, I can now extract the transformations and above all, they are
now very accurate! Thanks a lot for your valuable information, that is exactly what I wanted know
and I highly appreciate!

Best regards

George



Marco Schlichting wrote:

> Hello George,
>
> my previous e-mail is maybe not exactely what you wanted to know.
> Ok, I will try again.
> To get the orientation from the transform object you should write
> somrthing as followed:
>
> float* orientation;
> oreintation = trans->GetOrientation();
>
> Than the orientation Rx, Ry, Rz can be accessed with orientation[0],
> orientation[1] and orientation[2].
>
> Further there is no mistake in the calculation of the matrixes. The
> solution is quite simple. If you rotate an object about 90 degrees
> about the X-axis. The Y-axis becomes the Z-axis and further
> calculation will have a different effect than you suppose. It
> is called Gimbal lock.
>
> see
> W. Schroeder ea.,
> The Visualization ToolKit, an object oriented approach to 3D graphics.
> Prentice Hall PTR, 1997
> page: 74
>
> CU MARCO
>
> PS: hope that will give you a hint
>
> George Kamucha wrote:
> >
> > Hi all,
> > I am still very eager to know what kind of an output one expects from
> > the vtkTransform::GetOrientation(), anybody out there who can help me in
> > this please? I tried something simple, below:
> >
> > vtkTransform *trans = vtkTransform::New();
> >             trans->Identity();
> >             trans->PostMultiply();
> >             trans->RotateY(10);
> >             trans->RotateX(20);
> >             trans->RotateZ(30);
> >             trans->GetOrientation();
> >
> > I was expecting the output to be just three elements (so I have read
> > from the Manpages!), but I instead got a matrix which after decomposing
> > ( a lot of work!), gave seemingly the following: Y=9.39, X=20.3 and
> > Z=33.4. So I am wondering, how come I am not getting the three angles as
> >
> > opposed to a matrix, and is the error usually this big?. Please assist.
> >
> > Regards
> >
> > George
> >
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> --
> -----------------------------------------------------------------------
> Marco Schlichting               Philips Research Laboratories Eindhoven
> Building: WY p2.20              Prof. Holstlaan 4
> Phone: +31 40 27 42 63 8        5656 AA  Eindhoven
>                                 The Netherlands
> mailto:schlicht at natlab.research.philips.com