[ITK] Fwd: Image Pyramid Speed

[Nicolas Gallego]

Good morning Stephen,

I have read recently de multi resolution pyramid filter and I just read the
documentation for the registration method (version 4.5.0)
there is a warning about the discrepancy of requested levels and a default
schedule that one should check.

It could be easier to point your issue if post the portion of the code you
are testing.

It may depend also of the particular parameters you are using
or the way you are measuring time, see

http://www.itk.org/Wiki/ITK/Examples/Utilities/TimeProbe

this watcher can inspire you to check some events, progress and time
measurements
http://www.itk.org/Wiki/ITK/Examples/Utilities/SimpleFilterWatcher

hope that helps

-- 
Nicolás Gallego-Ortiz
Université catholique de Louvain, Belgium



2014-05-19 14:34 GMT+02:00 Stephen Parsons <stephen.parsons at uky.edu>:

> I have been attempting to use the MultiResolutionImageRegistrationMethod.
> As I understand it, the input images are blurred and then resampled to
> create smaller internal images on which the registration operates for the
> lower levels. I have set the number of levels and the starting shrink
> factors and by outputting the shrink factor at each level I have confirmed
> that it seems to be set up correctly (shrink factors are halved with each
> new level).
>
> The program will run and produce correctly registered output, but each
> iteration takes just as long as it did before I implemented the image
> pyramid, when it was operating on full size images. Running smaller images
> through the pipeline leads to a dramatic increase in speed which made me
> think that the image pyramid in MultiResolutionImageRegistrationMethod
> would allow for the same speed increase, at least in the beginning levels.
> With the image pyramid there is no speed decrease as it proceeds through
> the pyramid levels, the first takes just as long as the last.
>
> What could I have missed that would make the image pyramid just as slow as
> not having it implemented at all? Have I misunderstood something about the
> way it is implemented or is intended to be used?
>
> Thanks,
> Stephen Parsons
> University of Kentucky
>
>
> _______________________________________________
> Community mailing list
> Community at itk.org
> http://public.kitware.com/cgi-bin/mailman/listinfo/community
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/community/attachments/20140520/36699725/attachment-0002.html>