[ITK-users] FW: ExtractImageFilter.Update() inside loop works until 24th iteration

[Francois Budin]

Hello Fabio,

When you say "avoid connecting its components with SetInput(GetOutput())",
do you mean that you used the method "DisconnectPipeline()"?

Francois

On Sun, Jan 1, 2017 at 5:40 PM, D'Isidoro Fabio <fisidoro at ethz.ch> wrote:

> Update: generalizing the problem, I figured out that any time the final
> filter is updated inside a loop, after a certain number of iterations the
> Update() does not work anymore and filter.GetOutput() returns always the
> same image as the last working iteration. I guess it’s a memory issue. This
> issue happens no matter what the final filter of the pipeline is (I tried
> with ResampleImageFilter, Writer, ExtractImageFilter), and even when using
> the filter.InPlaceOn() when possible. This issue happens even if I split
> the pipeline and avoid connecting its components with SetInput( GetOutput()
> ).
>
>
>
> Are filters of a pipeline not supposed to be used in a loop (where, in my
> case, the given transform changes at any loop)?
>
>
>
> I guess the issue formulated this way is a common issue.
>
>
>
> Thank you for your help.
>
>
>
> Fabio.
>
>
>
> *From:* D'Isidoro Fabio
> *Sent:* Sonntag, 1. Januar 2017 19:48
> *To:* insight-users at itk.org
> *Subject:* ExtractImageFilter.Update() inside loop works until 24th
> iteration
>
>
>
> Hallo,
>
>
>
> I work with ITK Python. I need to explore the domain of an image metric
> (like in MeanSquaresImageMetric1.cxx) for 2D/3D registration (using
> RayCastInterpolator). Since the metric works only between 2D/2D or 3D/3D
> images, I need to convert the generated DRR (SizeX, SizeY, 1) into a 2D
> image (SizeX, SizeY) with ExtractImageFilter, before metric evaluation. I
> then pass to the metric the converted 2D DRR as moving image and the 2D
> fixed image for similarity metric evaluation (with IdentityTransform, and
> NearestNeighbourInterpolator set for the metric). Metric evaluation is done
> in a loop within a range of the domain for the transform parameters. For
> each iteration of the loop (that is, different transforms used for
> generation of the DRR) the ExtractImageFilter is updated with Update().
>
>
>
> The code runs but mysteriously stops working properly at the 24th
> iteration of the loop for the domain range. After the 24th iteration I
> figured no new DRR is generated and the metric value keeps constant at the
> value of the 24th iteration. I tried with input 3D volumes of different
> sizes and with different ranges for the transform parameters, but the code
> stops generating new DRRs always after the 24th iteration.
>
>
>
> The important parts of the code are:
>
>
>
> interpolatorRayCast = itk.RayCastInterpolateImageFunction[MovingImageType,
> ScalarType].New()
>
> filterRayCast = itk.ResampleImageFilter[MovingImageType,
> MovingImageType].New()
>
> filterRedim = itk.ExtractImageFilter[MovingImageType,
> FixedImageType].New()
>
> …
>
> filterRayCast.SetInput( movingImageReader.GetOutput() )
>
> filterRayCast.SetInterpolator( interpolatorRayCast )
>
> …
>
> filterRedim.SetInput(filterRayCast.GetOutput())
>
> …
>
> for dx in translation_range_x:
>
>     for dy in translation_range_y:
>
>         for dz in translation_range_z:
>
> …
>
> transformDRR.SetParameters( transform_parameters )
>
>
>
>                                filterRedim.Update()
>
>
>
>              value = metric.GetValue()
>
>
>
>
>
> I believe the pipeline might not be set properly, but I don’t know where.
>
>
>
> In attachment you find the code and the required inputs.
>
>
>
> Any help would be highly appreciated, thank you!
>
>
>
> Fabio.
>
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