[Insight-users] Question regarding itkParallelSparseFieldLevelSetImageFilter

[Luca Antiga]

Hi Michael,
  there shouldn't be any extra difference between the serial and  
parallel versions except from multithreading.
Although not as straightforward as for the serial version, it is  
already possible to achieve what you want
(e.g. use geodesic active contours in parallel) by instantiating a  
itkParallelSparseFieldLevelSetImageFilter and a  
GeodesicActiveContourLevelSetFunction separately, and plugging the  
function into the filter using SetDifferenceFunction.
If you look into itkGeodesicActiveContourLevelSetImageFilter.txx,  
you'll see that there isn't much else that the high-level
filter is actually doing.
I wouldn't use the parallel version by default, since it's heavier,  
it does a lot more checking and has a few extra data
structures. Level sets are already heavy the way they are.
Apart from what I suggested above, there could be two things that can  
be done:
1. making the super class of  
itkGeodesicActiveContourLevelSetImageFilter (and the other high-level  
classes) a template
parameter, which defaults to the serial version. However, I didn't  
see this kind of solutions being adopted a lot in ITK.
2. creating parallel versions of the high level filters. Some code  
replication involved, but not a lot.
Greets

Luca


On Mar 3, 2008, at 4:33 PM, Michael Schmidt wrote:

> Hi,
>
> I have a question regarding the usage of the  
> itkParallelSparseFieldLevelSetImageFilter. Is there - except for  
> multithreading - a difference between the parallel filter and the  
> itkSparseFieldLevelSetImageFilter? Why are all the "higher level"  
> LevelSetFilters like itkGeodesicActiveContourLevelSetImageFilter  
> derived from the single-threaded filter? Are there performance  
> issues with the parallel version on a single-core cpu? Or did I  
> miss something else? Will it be possible to simply exchange the  
> single-threaded filter with the parallel filter?
>
> I would really appreciate some hints on this topic. Thanks in advance,
>
> Michael
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