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Re: 3d matrix rotation [message #33447 is a reply to message #33437]

Thu, 02 January 2003 15:56

Rick Towler
Messages: 821
Registered: August 1998

Senior Member

"David Fanning" <david@dfanning.com> wrote...
> New2IDL (biomedthesis2002@yahoo.com) writes:
>
>> I'm trying to rotate a 3D matrix using trackball. I have a 3D matrix
>> of size 512x512x25. Hwn i try to rotate it, the matrix stretches along
>> Z-axis. Hwn displayed the image is perfectly fine. Can anybody explain
>> why that happens and what can be done to fix it. When i tried a
>> dataset from the example (head.dat) for the same code, the rotation
>> takes place without any stretch.
>
> Sounds to me like you are applying the transformation matrix
> to the data itself, rather than to the model that holds
> the data. Apply the transformation to the model.

If all you wish to do is to visualize your data then as David is hinting you
may want to create an IDLgrVolume object with your data, place that into a
IDLgrModel object and then apply the transform from your trackball to the
IDLgrModel transform.

If you have a reason to apply the transform directly to your data then look
for differences between your data set and head.dat (which you said
transforms correctly). It is hard to say much more since your posting is a
bit vague. You say the matrix stretches along the Z-axis but then you say
the image is "perfectly fine". What image?

-Rick

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[Message index]

		Re: 3d matrix rotation By: jacobian on Sun, 05 January 2003 11:01
		Re: 3d matrix rotation By: Rick Towler on Thu, 02 January 2003 15:56
		Re: 3d matrix rotation By: David Fanning on Thu, 02 January 2003 13:20

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