[vtkusers] stenciling problem-- is this code thread safe?

[David Gobbi]

The vtkPolyDataToImageStencil in VTK 5.8 and 5.9 can take a polyline
contour or a stack of contours as input and create a stencil from
that.  Each polylines should lie in an XY plane (though they can be at
any Z position).  This will not work with a polygon; a polyline is
required.

 - David


On Fri, Feb 11, 2011 at 11:51 AM, Mark Roden <mmroden at gmail.com> wrote:
> Hi David,
>
> How should the stenciling be done in vtk 5.9 then?  If I remove the
> linear extrusion, no masks are produced.
>
> This is exciting-- I can now use the vtkSmartVolumeMapper, which I've
> been drooling over ever since it was introduced!
>
> Thanks,
> Mark
>
> On Fri, Feb 11, 2011 at 10:39 AM, Mark Roden <mmroden at gmail.com> wrote:
>> wait, never mind!  I had some issues with vtk strings, but it appears
>> that this line:
>>
>> outWin.SetInstance(outWin);
>>
>> is now deprecated or something, because having that line active in this snippet:
>>
>>            vtkFileOutputWindow outWin = new vtkFileOutputWindow();
>>            outWin.SetInstance(outWin);
>>            outWin.SetFileName("MVSVTKViewer.log");
>>
>> throws this exception:
>>
>> Exception in thread "main" java.lang.NoSuchFieldError: vtkId
>>        at vtk.vtkOutputWindow.SetInstance_3(Native Method)
>>        at vtk.vtkOutputWindow.SetInstance(vtkOutputWindow.java:45)
>>        at com.mvs.viewer.Application.main(Application.java:63)
>>
>> But that's a different issue (bug?)
>>
>> On Fri, Feb 11, 2011 at 10:35 AM, David Gobbi <david.gobbi at gmail.com> wrote:
>>> If you are reporting the vtkLinearExtrusionFilter, I already did.
>>>
>>> On Fri, Feb 11, 2011 at 11:31 AM, Mark Roden <mmroden at gmail.com> wrote:
>>>> Hi David,
>>>>
>>>> Unfortunately,  the current vtk master branch is seriously broken in
>>>> its java wrappings.  I'm putting together a bug report now...
>>>>
>>>> Thanks,
>>>> Mark
>>>>
>>>> On Fri, Feb 11, 2011 at 10:09 AM, David Gobbi <david.gobbi at gmail.com> wrote:
>>>>> I should add: with the current VTK master and release branches,
>>>>> vtkPolyDataToImageStencil no longer requires vtkLinearExtrusionFilter
>>>>> to be used beforehand.  So you could try that.
>>>>>
>>>>>  - David
>>>>>
>>>>>
>>>>> On Fri, Feb 11, 2011 at 11:06 AM, David Gobbi <david.gobbi at gmail.com> wrote:
>>>>>> I was doubtful about the global memory, but I looked through the
>>>>>> filters just to be sure.  And guess what I found... here is some
>>>>>> highly suspect code in vtkLinearExtrusionFilter:
>>>>>>
>>>>>> double *vtkLinearExtrusionFilter::ViaNormal(double x[3], vtkIdType id,
>>>>>>                                           vtkDataArray *n)
>>>>>> {
>>>>>>  static double xNew[3], normal[3];
>>>>>>  int i;
>>>>>>
>>>>>>  n->GetTuple(id, normal);
>>>>>>  for (i=0; i<3; i++)
>>>>>>    {
>>>>>>    xNew[i] = x[i] + this->ScaleFactor*normal[i];
>>>>>>    }
>>>>>>
>>>>>>  return xNew;
>>>>>> }
>>>>>>
>>>>>> Code like the above is definitely going to cause thread problems.
>>>>>> And this isn't the only place in that class where code like this appears.
>>>>>>
>>>>>> Yikes!
>>>>>>
>>>>>>  - David
>>>>>>
>>>>>>
>>>>>> On Fri, Feb 11, 2011 at 10:46 AM, Mark Roden <mmroden at gmail.com> wrote:
>>>>>>> What I mean is, I have a vtkPolyData that has been DeepCopied and a
>>>>>>> vtkImageData that is binary and distinct from all other data.
>>>>>>>
>>>>>>> When I call the previously listed code with multiple threads (each
>>>>>>> with their own polydata and binary image to fill in), the result is
>>>>>>> generally a very garbled image.  If I call from a single thread in
>>>>>>> series, one for each polydata/image pair, then everything works out
>>>>>>> fine.
>>>>>>>
>>>>>>> So it seems to me that something in the above series isn't thread
>>>>>>> safe.  Each thread is declaring its own local objects, but is there
>>>>>>> some global memory that's being used or accessed here?
>>>>>>>
>>>>>>> On Fri, Feb 11, 2011 at 9:23 AM, David Gobbi <david.gobbi at gmail.com> wrote:
>>>>>>>> Hi Mark,
>>>>>>>>
>>>>>>>> Explain in more detail what you mean by "call from multiple threads".
>>>>>>>> VTK is, in general, not thread safe and you cannot call Update() on
>>>>>>>> a filter from more than one thread.  Each thread needs to have its own
>>>>>>>> set of filters.  And in general, you cannot feed a data object into more
>>>>>>>> than one thread, because even simple methods like GetBounds() are
>>>>>>>> not thread safe.
>>>>>>>>
>>>>>>>> When using VTK from multiple threads, it is necessary to apply
>>>>>>>> extreme caution.
>>>>>>>>
>>>>>>>>  - David
>>>>>>>>
>>>>>>>>
>>>>>>>> On Fri, Feb 11, 2011 at 10:00 AM, Mark Roden <mmroden at gmail.com> wrote:
>>>>>>>>> Hi all,
>>>>>>>>>
>>>>>>>>> This code does not have threads enabled in vtk 5.6.1 (the code is in Java):
>>>>>>>>>
>>>>>>>>>        vtkLinearExtrusionFilter extruder = new vtkLinearExtrusionFilter();
>>>>>>>>>        extruder.SetInput(data);
>>>>>>>>>        extruder.SetVector(0, 0, spacing[2]);
>>>>>>>>>        extruder.Update();
>>>>>>>>>        vtkPolyData extruderOutput = extruder.GetOutput();
>>>>>>>>>
>>>>>>>>>        vtkPolyDataToImageStencil pol2Stenc = new vtkPolyDataToImageStencil();
>>>>>>>>>        pol2Stenc.SetTolerance(0);
>>>>>>>>>        pol2Stenc.SetInput(extruderOutput);
>>>>>>>>>        pol2Stenc.SetInformationInput(binaryOrgan);
>>>>>>>>>        pol2Stenc.Update();
>>>>>>>>>        vtkImageStencilData pol2StencOutput = pol2Stenc.GetOutput();
>>>>>>>>>
>>>>>>>>>        // This is where the memory leak is!!!!
>>>>>>>>>        vtkImageStencil stencil = new vtkImageStencil();
>>>>>>>>>        stencil.SetInput(binaryOrgan);
>>>>>>>>>        stencil.ReverseStencilOn();
>>>>>>>>>        stencil.SetStencil(pol2StencOutput);
>>>>>>>>>        stencil.Update();
>>>>>>>>>
>>>>>>>>>        // We're doing this because of an email to Mark
>>>>>>>>>        // that says this will fix our memory issues
>>>>>>>>>        final vtkImageData stencilOutput = stencil.GetOutput();
>>>>>>>>>        final vtkImageData imageToKeep = new vtkImageData();
>>>>>>>>>        imageToKeep.DeepCopy(stencilOutput);
>>>>>>>>>        stencilOutput.Delete();
>>>>>>>>>
>>>>>>>>> When I try to call this code from multiple threads (ie, to create the
>>>>>>>>> stencils for multiple organs), Bad Things happen, as in, the data are
>>>>>>>>> entirely corrupted.  Is this code thread safe?
>>>>>>>>>
>>>>>>>>> Mark
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>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
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