Hi,
To elaborate slightly...
Point correspondence is implicit to the models/methodology used in
FIRST. To train the models, the manually labeled
data is parameterized using deformable surfaces (similar to that used
in bet). The forces applied
to the surface were designed to minimize within-surface motion and
retain correspondence.
A multivariate point distribution model of shape is used, such that
shape is parameterized by the mean and
eigenvectors. The shape space is restricted to linear combinations of
the mean and eigenvectors, hence retaining the correspondence imposed
by the training process. For most structures the initial surface was
deformed from a sphere,
the others were initialized using marching cubes on an average image.
Cheers,
Brian
On 20 May 2008, at 08:16, Steve Smith wrote:
> Hi - FIRST outputs vtk mesh files which is probably a lot more use
> to use than the 3D image masks, and they're easy to read. These do
> indeed have spherical topology.
>
> Cheers.
>
>
> On 20 May 2008, at 00:54, Mohammad Bhuyan wrote:
>
>> Hi All,
>>
>> I am trying to do statistical shape analysis of Barin structures
>> where the
>> masks are generated using the FIRST and then run SPHARM analysis.
>>
>> So it is important to ensure the spherical topology to the masks
>> (so that
>> there are no holes/handles in the volume). Where I can use such
>> tools for
>> correction but there is no point if FIRST generates masks where
>> the topology
>> is ensured. Somewhere I heard that FIRST ensures spherical
>> topology of
>> the masks.
>>
>> Can anybody confirm that?
>>
>> Cheers,
>>
>> Mohammad
>>
>> PS: Please ignore my last email as it was sent out in error
>> without subject.
>>
>
>
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> Stephen M. Smith, Professor of Biomedical Engineering
> Associate Director, Oxford University FMRIB Centre
>
> FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
> +44 (0) 1865 222726 (fax 222717)
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