[Insight-users] Possible bug: itkImageToVTKImageFilter not updating when expected

[Parag Chandra]

Hi Luis,

I tried called Modified() on the image as soon as I connect it to the
pipeline; no luck. And the way I add the images into my std::vector after
reading them in is simply by calling push_back(). Thanks for your
suggestions, but don't worry about it anymore since I have a workaround
right now. Once I upgrade to the latest releases of ITK/VTK, I will check to
see if the problem persists and then I will get back to you.

Best regards,
-Parag

----- Original Message -----
From: "Luis Ibanez" <luis.ibanez@kitware.com>
To: "Parag Chandra" <pchandra@radonc.unc.edu>
Cc: "ITK Mailing List" <insight-users@public.kitware.com>
Sent: Friday, March 21, 2003 10:25 PM
Subject: Re: [Insight-users] Possible bug: itkImageToVTKImageFilter not
updating when expected


>
> Hi Parag,
>
> Here are several factors that can help
>
> 1) The ImageToVTKImageFilter is not properly
>     a filter. It is just a class grouping a
>     itkImageExporter with a vtkImageImporter.
>
>     So, when you call "Update" it is not
>     doing anything.
>
>     That being said, the fact that its output
>     is the output of the vktImporter, make that
>     it should behave normally in a pipeline.
>
> 2) Something seems to be non standard in the
>     way the image are in the std::vector<>.
>
>     What method did you finally used to put
>     these images in the std::vector<> after
>     reading them from files ?
>
> 3) Could you try calling ->Modified() in
>     the image as soon as it is connected
>     to the ITK to VTK filter, in the slider
>     callback ?
>
>     It could be that the filter doesn't
>     realize that it is now receiving new
>     data and henceforth it is time to update.
>
>
>
>     Luis
>
>
>
>
> -----------------------
>
> Parag Chandra wrote:
> > Hey Luis,
> >
> > Yes, the slider also manually calls Render(). Really the only difference
I
> > can think of between the two applications is the manner in which the
image
> > is provided as input.
> >
> > Best regards,
> > -Parag
> >
> > ----- Original Message -----
> > From: "Luis Ibanez" <luis.ibanez@kitware.com>
> > To: "Parag Chandra" <pchandra@radonc.unc.edu>
> > Cc: "ITK Mailing List" <insight-users@public.kitware.com>
> > Sent: Friday, March 21, 2003 6:22 PM
> > Subject: Re: [Insight-users] Possible bug: itkImageToVTKImageFilter not
> > updating when expected
> >
> >
> >
> >>Hi Parag,
> >>
> >>Does the callback for the slider also calls Render()
> >>on the interactors render window ?
> >>
> >>In addition to switching the input image, you may want
> >>to call Render() again, since the pipeline is driven by
> >>demand, changing inputs will not force the update of
> >>filters downstream.
> >>
> >>
> >>You have to pull data from the end of the pipeline.
> >>
> >>
> >>
> >>Regards,
> >>
> >>
> >>    Luis
> >>
> >>
> >>------------------------------------
> >>
> >>Parag Chandra wrote:
> >>
> >>>I'm seeing a problem where my ITK->VTK pipeline isn't getting updated
> >>>correctly, but a seemingly unnecessary workaround fixes the problem, so
> >>>I thought this might be a bug.
> >>>
> >>>In short, I have subclassed vtkFlRenderWindowInteractor to
> >>>create HeightFieldInteractor, which simply takes an input ITK 2D image
> >>>and displays it as a height field, using itkImageToVTKImageFilter. I've
> >>>then created an application that embeds this HeightFieldInteractor
> >>>widget into its main window. The application just lets you load an ITK
> >>>image from disk and then displays it as a height field. So the pipeline
> >>>is something like:
> >>>
> >>>itkImageFileReader -> itkImageToVTKImageFilter ->
> >>>vtkImageDataGeometryFilter -> vtkWarpScalarFilter -> vtkPolyDataMapper
> >>>-> vtkActor
> >>>
> >>>This application works perfectly: as soon as I load a new image from
> >>>disk, I call Render() on the interactor's RenderWindow, and the window
> >>>is updated to reflect the contents of the new image.
> >>>
> >>>A second application embeds both the same HeightFieldInteractor and an
> >>>additional instance of vtkFlRenderWindowInteractor into its main
window.
> >>>This application loads a series of a dozen or so 2-D ITK images at
> >>>startup and keeps them around in a std::vector. I then use a slider to
> >>>select between these images, and the callback for the slider simply
sets
> >>>the input of itkImageToVTKImageFilter to the appropriate image stored
in
> >>>the vector. So the pipeline is something like this:
> >>>
> >>>vectorOfImages[sliderValue] -> itkImageToVTKImageFilter -> etc.
> >>>
> >>>In this instance, the render window never gets updated no matter how
> >>>many times the slider is moved around; it always shows the first image
> >>>that was set. I even tried manually calling Modified() and Update() on
> >>>the itkImageToVTKImageFilter, as well as manually Update()'ing other
> >>>filters farther up/down the pipeline, but to no avail. However, if I
> >>>insert a simple CopyFilter that I created into the pipeline above:
> >>>
> >>>vectorOfImages[sliderValue] -> myCopyImageFilter ->
> >>>itkImageToVTKImageFilter -> etc.
> >>>
> >>>then the updates happen correctly. This CopyImageFilter simply copies
> >>>the input image over to the output unchanged.
> >>>
> >>>Does someone with a better knowledge of the internal workings of ITK
and
> >>>VTK have an idea what might be going on here? I should again note that
> >>>I'm still using ITK 1.0 and VTK 4.0 on Windows, so sorry if this has
> >>>already been fixed. I'm just holding off on upgrading to the latest
> >>>versions until I reach certain milestones in my project. Thanks.
> >>>
> >>>Best regards,
> >>>-Parag Chandra
> >>
> >>
> >>
> >
> > _______________________________________________
> > Insight-users mailing list
> > Insight-users@public.kitware.com
> > http://public.kitware.com/mailman/listinfo/insight-users
> >
>
>
>