[vtkusers] Left-Handed vs. Rigth-Handed

[Andres Barrera]

Hello

    Please disregard my previous e-mail... I apologize for wasting your 
time, I think there was a mistake on the tutorial I was using: the 
definitions for Right and Left handed rotations are switched. I confirmed 
that on a couple of books.

   Thanks

               Andres


>From: "Andres Barrera" <andresba at hotmail.com>
>To: vtkusers at vtk.org
>Subject: [vtkusers] Left-Handed vs. Rigth-Handed
>Date: Thu, 17 Aug 2006 12:09:37 -0500
>
>Hello, I have a question regarding to LH -  RH transformation (Rotations).
>
>   I understand that VTK uses RH system, but on pages 52-53 of "The 
>Visualization Toolkit-2nd edition", the rotation matrices presented are for 
>a LH. Is there any reason to use LH in VTK?
>
>   On the other hand, have some results that are unclear to me:
>     1.  I apply some transformation to an actor (origin of actor @ 0, 0, 0 
>) in VTK using quaternions.
>
>     2. Retrieve the UserTranf matrix
>   (e.g.
>          Elements:
>        0.0226843   0.0076929  0.999712     24.9333
>        0.709023     0.704857  -0.0215119  -50.5692
>        -0.70482      0.709307   0.0105338   36.2352
>        0                  0                 0                   1
>    )
>
>     3. Retrieve the position and orientation of such actor using
>          float         auxPos[3] = {0.0, 0.0, 0.0};
>          float         auxRot[3] = {0.0, 0.0, 0.0};
>          …
>          auxTransform->GetPosition     ( auxPos );
>          auxTransform->GetOrientation( auxRot );
>
>     (e.g.
>	auxPos =  24.9333	-50.5692	36.2352
>	auxRot =  45.1786	89.1437	-0.625325
>      )
>    4.  I’ve implemented ‘by hand’ R(rh) = Rz*Rx*Ry , and R(lh) = Rz*Rx*Ry 
>(‘rh’ for rigthH and ‘lh’ for leftH).
>
>        I was expecting R(rh) to be equal to ‘UserTranf matrix’, but is 
>not, and actually R(lh)is
>
>Left Handed
>---------------
>Rz * Rx * Ry = 0.022684158   0.007693103     0.999713081    0
>                     0.709022949   0.704857204    -0.021446423    0
>                    -0.704820464    0.709307506    0.010534505    0
>                              0	              0	                   0        
>             1
>
>Right Handed
>--------------------
>Rz * Rx * Ry =   0.007203458    -0.007693103    -0.999944462	0
>                       0.709349155     0.704857204    -0.000378667	0
>                       0.704820464    -0.709307506    0.010534505	0
>                                0	          0	          0                   
>  1
>
>
>      Any ideas on what might be going wrong? Thanks.
>
>            Andres
>
>
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