[Insight-users] Does registration preserve physical dimensions?

[Miller, James V (Research)]

It depends on the type of transformation you use.  If you use a rigid body 
transform, then physical dimensions will be preserved.  This would mean
in your transplant case, the object will not occupt the same amount 
of space since they are different sizes.

If you use a more flexibly transform (affine, bspline, etc), then physical dimensions
will not be preserved.

Jim

-----Original Message-----
From: insight-users-bounces+millerjv=crd.ge.com at itk.org
[mailto:insight-users-bounces+millerjv=crd.ge.com at itk.org]On Behalf Of
laurent.paul at club-internet.fr
Sent: Friday, May 13, 2005 11:06 AM
To: insight-users at itk.org
Subject: [Insight-users] Does registration preserve physical dimensions?



Hi all,

I work on registration between patient/transplant.
My work will determine if the transplant has right dimensions for the patient. 
In my case, I'm wondering if the registration preserves the physical dimensions.
After the registration, both volumes have the same dimensions because there's a scale applied on the moving volume for fitting in the fixed volume.
Is this reality? I mean, is the transplant really has the same physical dimensions as the patient's organ or is this just to obtain a right registration?

Let me take an example:
fixed volume: patient's organ
moving volume: transplant
We can imagine that the transplant measures 10 cm while the patient's organ is 20 cm. 
The transplant will be scaled after the registration. Will they be exactly superposed? Is both volumes have the same height on the screen?

I've ever registered two volumes coming from the same patient, there's no problem about dimensions
because it's the same patient, the same shape, but with two different objects I don't know....

Thanks,

Laurent.

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