[Insight-users] Registration of 3D images
Luis Ibanez
luis.ibanez@kitware.com
Thu, 17 Oct 2002 14:22:47 -0400
Hi Ghassan,
As you already said,
Performance of registration methods depends on many factors.
In general, you have to go through a process of fine-tunning
parameters if you want to get the best out of a registration
method.
Here is however, a nominal time that will give you an
idea of the order of magnitude for the registration time.
This is running an existing example in ITK:
Insight/Examples/MultiResMIRegistration
Which performs registration of 3D images using
- Multiresolution in a pyramid with 5 levels
- MutualInformation metric
- Affine transform (which in 3D == 12 Degrees of Freedom)
- GradientDescent optimizer 2500 iterations per level
Applying this method to two BrainWeb images in our ftp site:
- brainweb165a10f17.raw
- brainweb165a10f17Rot10Tx15.raw
Where the second image is a version of the first one
manually rotated 10 degrees and translated 15 mm.
The dimensions (in pixels) of these images are
181 x 217 x 181
with pixel spacings = 1.0 x 1.0 x 1.0 mm
The full processing took (as timed with Unix 'time'):
186.81s user 1.48s system 88% cpu 3:33.13 total
That is: roughtly 3 minutes.
This was executed in a single processor Pentium 4
at 1.8Ghz with 512Mb RAM. Under Linux Redhat 7.1,
compiled with gcc3.0.2. The program was compiled
for debugging (without any optimization).
The results were:
Overall transform matrix:
0.984805 0.173661 -5.92032e-05
-0.173661 0.984805 -9.64365e-05
4.15563e-05 0.000105253 1.0
Overall transform offset:
-14.9961 0.0267664 -0.0157536
You can verify that 0.1736 is about the sin(10 deg)
and the translation of -14.99 is quite close to the
expected -15.0 value.
Please let us know if you have further questions.
Thanks
Luis
===============================================================
Hi,
I am interested in getting a rough idea on how long it takes to register
two 3D
volumes using ITK. I understand that this depends on many factors. Could
those
of you who have tried it provide me with feedback on their experience,
perhaps
by stating: time needed, computer/OS specs., spatial transformation/DOF,
dimension of images, etc, in a line or two,
Your feedback is very much appreciated,
/Ghassan
Ghassan Hamarneh, PhD
Hospital for Sick Children
Toronto, Canada