# Incorporating a 3x3 rotation matrix into a vtkTransform

Tim Hutton T.Hutton at eastman.ucl.ac.uk
Mon Jan 17 11:56:21 EST 2000

```No, the point sets are in 3d but thanks for your reply. I've been reliably
informed the solution is

T = a b c 0
d e f 0
g h i 0
0 0 0 1

Cheers,

Tim. (wishes he could understand homogeneous coordinates...)

At 16:48 17/01/00 -0000, you wrote:
>I've assumed your dealing with 2D (its 3x3), so the matrix should be:
>
>T = a b 0 c
>    d e 0 f
>    0 0 1 0
>    g h 0 i
>
>
>Steve.
>
>> -----Original Message-----
>> From: Tim Hutton [mailto:T.Hutton at eastman.ucl.ac.uk]
>> Sent: Monday, January 17, 2000 4:09 PM
>> To: vtkusers at gsao.med.ge.com
>> Subject: Incorporating a 3x3 rotation matrix into a vtkTransform
>>
>>
>> vtk users,
>>
>> Simple question, I'm a bit rusty with my 4x4 transformation
>> matrices. I
>> have a routine that computes the  rotation required to LS
>> align two sets of
>> points. It returns a 3x3 rotation matrix, how do I add this to a
>> vtkTransform. Is it as simple as adding a row of 1's?
>>
>> ie.
>>
>> R = a b c
>>     d e f
>>     g h i
>>
>> T = a b c 0
>>     d e f 0
>>     g h i 0
>>     1 1 1 1
>>
>> Or is it more complicated?
>>
>> Cheers,
>>
>> Tim.
>> --------------------------------------------------------------
>> -------------
>> Tim Hutton, Research Assistant            Email:
>> T.Hutton at eastman.ucl.ac.uk
>> MINORI Project
>> http://www.eastman.ucl.ac.uk/~dmi/MINORI
>> Dental and Medical
>> Informatics                   Tel: [+44] (0171) 915 2344
>> Eastman Dental Institute, UCL                    Fax: [+44]
>> (0171) 915 2303
>> 256 Gray's Inn Road, London WC1X 8LD, UK
>> --------------------------------------------------------------
>
>
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