[elastix] BendingEnergyPenalty speed
s.klein at erasmusmc.nl
Fri Jan 27 09:45:50 CET 2012
How many samples are you using now?
It's indeed possible to use a different sampler for the bending energy
than for the first similarity metric. Simply put something like:
(ImageSampler "Random" "Random" )
to specify a different number of samples for both:
On 27-1-2012 9:40, M.Staring at lumc.nl wrote:
> Dear Brecht,
> Those penalty terms are indeed slow; there has not been made
> performance improvements, and I also suspect no one over here has time
> or incentive to work on that. The penalty term also depends on the
> previous (initial) transform and does computations on that. So, the
> more initial transforms, the slower it is. If that is the case you may
> want to group those transform in a single transform. Two affine
> transforms can for example be perfectly grouped into a single affine
> transform, and two B-spline transforms can be approximated by a single
> Mathematically, it may be a bit dangerous to evaluate part of the cost
> function on other (less) samples, adding more noise to that part of
> the cost function. Practically, it may work, but I have never tried
> that. So, I would just try it out and check what you get.
> *From:*elastix-bounces at bigr.nl [mailto:elastix-bounces at bigr.nl] *On
> Behalf Of *Brecht Heyde
> *Sent:* donderdag 26 januari 2012 11:03
> *To:* elastix at bigr.nl
> *Cc:* 'Brecht Heyde'
> *Subject:* [elastix] BendingEnergyPenalty speed
> Dear Marius, dear Stefan and elastix users,
> As is also mentioned in the elastix user's guide, the current
> computational cost for the TransformBendingEnergyPenalty is quite
> substantial, especially for large 3D datasets. I started looking into
> the code and since all second order derivatives are all calculated
> analytically from the underlying B-splines, I started wondering where
> the bottleneck of the evaluation of this penalty might be.
> Have any performance improvements for this class been made lately?
> Would it make sense to evaluate it in less points to speed up the
> process (so attach another RegularGridSampler for example?) Has anyone
> thought of other solutions?
> Best regards,
> Brecht Heyde
> elastix mailing list
> elastix at bigr.nl
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