[Insight-users] Speed of Mutual Information calculation

[Markus Weigert]

Hi Luis,

thanks for your response.
I use the Viola - Wells implementation.
Strangely, the Mattes implementation is much faster.
I compiled for release with dbg. information on VC6
and used GradientDescentOptimizer, not RegularStepGradientDescentOptimizer.
I plot the progress from a Command Observer and currently don't use 
multiresolution
(only on the original resolution).

Cheers,
Markus


----- Original Message ----- 
From: "Luis Ibanez" <luis.ibanez at kitware.com>
To: "Markus Weigert" <m.weigert at fz-juelich.de>
Cc: <insight-users at itk.org>
Sent: Monday, May 15, 2006 4:40 PM
Subject: Re: [Insight-users] Speed of Mutual Information calculation


>
> Hi Markus,
>
> Nope, this is not the common time for this size of images.
>
> This type of registration should take about 2 minutes in
> a modern standard computer.
>
>
> Some questions:
>
>
> 1) Are you compiling your application for "Release" ?
>
> 2) Are you using multi-resolution ?
>
> 3) Are you using the GradientDescent or
>    the RegularGradientDescent optimizer ?
>
> 4) Are you plotting the progress of the optimizer ?
>    from a connected Command Observer ?
>
> 5) Which one of the 5 ITK implementations of
>    Mutual Information Metric  are you using  ?
>
>
>
> It is very likely that you are letting the optimizer run
> for a lot of uncessary iterations.
>
> Have you measure the time needed for performing One iteration ?
> This will indicate if the problem is to have too many iterations,
> or to have metric evaluations that are too slow.
>
>
>
> The best way to figure out the problem is to analyze the
> trace provided by the Command Observer.
>
> Given that you are testing with a 3D translation transform,
> you are in the lucky situation were you can actually plot
> the path of the optimizer in the parametric space.
>
> You could use a tool such as GNUplot, in order to see this
> path in 3D.  Other easy options are a VTK script, or saving
> the trace in a .vtk file and loading it into ParaView.
>
> Whi
>
>
>
>
> =====================
> Markus Weigert wrote:
>> Dear insight users,
>>  I currently try to register two 3D images (CT and MR)
>> by using mutual information as metric.
>> The images have a size of approx. 255 * 290 * 75 slices each (MR perhaps 
>> even more).
>> Although I use a very simple transformation (translation) and a 
>> graddescent
>> optimizer, one iteration of the optimizer takes more than 1.5h.
>>  Is this a common time for images of this size???
>> The metric uses 60000 spatial samples.
>> I thougt about using BSpline transform in the next step of the 
>> registration
>> with MI metric too, but I think I can forget to do this, if I have to 
>> deal with 3000 Parameters
>> to be optimized!
>>  Regards,
>> Markus
>>  ------------------------------------------------------------------------
>>
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>
>