[Insight-users] ”Hello World” Registration from the ItkSoftwareGuide?

[motes motes]

Thanks for the detailed/good explanation!

On Mon, Jun 22, 2009 at 1:06 AM, Luis Ibanez <luis.ibanez at kitware.com>wrote:

> Hi Motes,
>
> Your new images are not appropriate input data for
> an image registration test.
>
>          They contain almost no information.
>
> The local derivatives of the metric will be zero almost
> every where in the parametric space.
>
> The cost function of the problem that you have devised
> looks almost like a Diract delta.  It has constant values
> every where, an a very high value in a single point.
>
> No gradient-based optimizer would figure out in what
> direction to walk to get to the peak of the cost function.
>
> The only stochastic optimizer may have a chance to
> solve the problem that you have set, and still they could
> only solve it by accidentally hitting that singular point in
> which the cost function has a non trivial value.
>
> You should use images whose spatial distribution of
> pixel intensities can give you a local gradient on the
> Cost Function (image metric).
>
>
>
>      Regards
>
>
>             Luis
>
>
> ---------------------------------------
> On Sun, Jun 21, 2009 at 3:20 PM, motes motes <mort.motes at gmail.com> wrote:
>
>> I am playing around with the example from the ItkSoftwareGuide.pdf page
>> 316. When using the brain images I get rather good results:
>>
>> http://img37.imageshack.us/img37/4316/example1z.jpg
>>
>> showing in the order: fixed, moving, resampled, rescaled intensity.
>>
>> I have then tried making my own very simple fixed and moving image to
>> compare:
>>
>> http://img23.imageshack.us/img23/4744/example2t.jpg
>>
>> Here the result are not that well (the same order as above). For some
>> reason the box is only translated very little towards the position in the
>> fixed image. Any ideas why it does not align better with this simple
>> example? The resulting translation transform does not transform very
>> correct.
>>
>> _____________________________________
>> Powered by www.kitware.com
>>
>> Visit other Kitware open-source projects at
>> http://www.kitware.com/opensource/opensource.html
>>
>> Please keep messages on-topic and check the ITK FAQ at:
>> http://www.itk.org/Wiki/ITK_FAQ
>>
>> Follow this link to subscribe/unsubscribe:
>> http://www.itk.org/mailman/listinfo/insight-users
>>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.itk.org/pipermail/insight-users/attachments/20090622/cc01ea51/attachment.htm>