[vtkusers] Writing a JPEG from vtkActor

Tue Dec 20 12:00:57 EST 2005

For me the problem is VTK crashing on ShiftScale operation on files
containing many vector/scalar data. Paraview reads the file OK, VTK CVS
15DEC05 crashes. But if I break the file into one scalar per file the
problem is not there anymore. That is what I added to the bug tracker.
thank you
Dominik

Amy Squillacote wrote:
> At 11:30 AM 12/20/2005, Dominik Szczerba wrote:
> 
>> >
>> > I always have to check the source code to see which way it should go.
>> > Could I suggest adding a simpler API like:
>> >
>> >  SetOutputRange(lowValue, highValue)?
>>
>>
>> I strongly second the notion.
>> Dominik
> 
> 
> So this suggestion doesn't get lost, please add this as a feature
> request to the bug tracker: http://public.kitware.com/Bug/.  (You'll
> need to create an account for yourself in the bug tracker in order to
> add a bug / feature request.)
> 
> - Amy
> 
>> >
>> >>
>> >>
>> >>>   vtkPNGWriter* writer = vtkPNGWriter::New();
>> >>>   writer->SetInput(iss->GetOutput());
>> >>>   writer->SetFileName(argv[2]);
>> >>>   writer->Write();
>> >>>
>> >>> Always the first scalar is taken, regardles of explicit selection
>> with
>> >>> setActiveScalarrs. The info seems displayed properly (of the first
>> >>> scalar) whih is in my case -9.11732e-06 1.53533e-05, output is black
>> >>> image (empty histogram).
>> >>> I will be grateful if you shed some light on this mystery.
>> >>> Dominik
>> >>>
>> >>> Amy Squillacote wrote:
>> >>> > Try using vtkImageShiftScale instead.  Do something like the
>> >>> following.
>> >>> >
>> >>> > double range[2];
>> >>> > grid->GetCellData()->GetScalars("abc")->GetScalarRange(range);
>> >>> >
>> >>> > vtkImageShiftScale *iss = vtkImageShiftScale::New();
>> >>> > iss->SetInput(grid);
>> >>> > iss->SetOutputScalarTypeToUnsignedChar();
>> >>> > iss->SetShift(-range[0]);
>> >>> > iss->SetScale((range[1] - range[0]) / 256.0);
>> >>> >
>> >>> > Are you sure that the data in your grid (a vtkImageData, I assume)
>> >>> is in
>> >>> > cell data? It's usually in point data.
>> >>> >
>> >>> > - Amy
>> >>> >
>> >>> > At 09:44 AM 12/20/2005, Dominik Szczerba wrote:
>> >>> >
>> >>> >> Thanks a lot, yes, I am trying the vtkImageCast, compiles fine,
>> >>> but get
>> >>> >> a black image at the end. Shouldnt I set ranges somewhere?
>> >>> >> I can do
>> >>> >>
>> >>> >> grid->GetCellData()->GetScalars("abc")->GetRange())
>> >>> >>
>> >>> >> but where do I plug the output?
>> >>> >>
>> >>> >> Dominik
>> >>> >>
>> >>> >> Amy Squillacote wrote:
>> >>> >> > Try using either vtkImageCast or vtkImageShiftScale to change
>> your
>> >>> >> image
>> >>> >> > data to contain either unsigned char or unsigned short data.
>> >>> >> >
>> >>> >> > - Amy
>> >>> >> >
>> >>> >> > At 08:58 AM 12/20/2005, Dominik Szczerba wrote:
>> >>> >> >
>> >>> >> >> What is the error? I try to do the same with vtkPNGWriter
>> >>> ending up
>> >>> >> with:
>> >>> >> >>
>> >>> >> >> vtkPNGWriter (0x8058948): PNGWriter only supports unsigned char
>> >>> and
>> >>> >> >> unsigned short inputs
>> >>> >> >>
>> >>> >> >> Meanwhile I try to figure out how to do the appropriate
>> >>> convertion in
>> >>> >> >> vtk.
>> >>> >> >> --dsz
>> >>> >> >>
>> >>> >> >> Marlos Fabris wrote:
>> >>> >> >> > Hi,
>> >>> >> >> >
>> >>> >> >> > I'm trying to write a jpeg file (using vtkJPEGWriter) from a
>> >>> >> vtkActor
>> >>> >> >> > but I can't accomplish this. I have a vtk file with
>> structured
>> >>> >> points
>> >>> >> >> > data and I wish to transform to vtkPolyData and color it
>> with my
>> >>> >> >> > vtkLookupTable.
>> >>> >> >> >
>> >>> >> >> > Is there a way to convert only my vtkActor to a vtkImageData,
>> >>> >> without
>> >>> >> >> > the frameborders of vtkWindowToImageFilter?
>> >>> >> >> >
>> >>> >> >> > Or is there a way to trim my image?
>> >>> >> >> >
>> >>> >> >> > Thank you in advance,
>> >>> >> >> >
>> >>> >> >> > Marlos Fabris
>> >>> >> >> > _______________________________________________
>> >>> >> >> > This is the private VTK discussion list.
>> >>> >> >> > Please keep messages on-topic. Check the FAQ at:
>> >>> >> >> http://www.vtk.org/Wiki/VTK_FAQ
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>> >>> >> >>
>> >>> >> >> --
>> >>> >> >> Dominik Szczerba, Dr.
>> >>> >> >> ETZ C110 CO-ME/BIWI CH-8092 Zurich
>> >>> >> >> http://www.vision.ee.ethz.ch/~domi
>> >>> >> >> _______________________________________________
>> >>> >> >> This is the private VTK discussion list.
>> >>> >> >> Please keep messages on-topic. Check the FAQ at:
>> >>> >> >> http://www.vtk.org/Wiki/VTK_FAQ
>> >>> >> >> Follow this link to subscribe/unsubscribe:
>> >>> >> >> http://www.vtk.org/mailman/listinfo/vtkusers
>> >>> >>
>> >>> >> --
>> >>> >> Dominik Szczerba, Dr.
>> >>> >> ETZ C110 CO-ME/BIWI CH-8092 Zurich
>> >>> >> http://www.vision.ee.ethz.ch/~domi
>> >>> >> _______________________________________________
>> >>> >> This is the private VTK discussion list.
>> >>> >> Please keep messages on-topic. Check the FAQ at:
>> >>> >> http://www.vtk.org/Wiki/VTK_FAQ
>> >>> >> Follow this link to subscribe/unsubscribe:
>> >>> >> http://www.vtk.org/mailman/listinfo/vtkusers
>> >>>
>> >>> --
>> >>> Dominik Szczerba, Dr.
>> >>> ETZ C110 CO-ME/BIWI CH-8092 Zurich
>> >>> http://www.vision.ee.ethz.ch/~domi
>> >>> _______________________________________________
>> >>> This is the private VTK discussion list.
>> >>> Please keep messages on-topic. Check the FAQ at:
>> >>> http://www.vtk.org/Wiki/VTK_FAQ
>> >>> Follow this link to subscribe/unsubscribe:
>> >>> http://www.vtk.org/mailman/listinfo/vtkusers
>> >>
>> >>
>> >> _______________________________________________
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>> >
>> >
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>> -- 
>> Dominik Szczerba, Dr.
>> ETZ C110 CO-ME/BIWI CH-8092 Zurich
>> http://www.vision.ee.ethz.ch/~domi
>> _______________________________________________
>> This is the private VTK discussion list.
>> Please keep messages on-topic. Check the FAQ at:
>> http://www.vtk.org/Wiki/VTK_FAQ
>> Follow this link to subscribe/unsubscribe:
>> http://www.vtk.org/mailman/listinfo/vtkuser
> 
> s

-- 
Dominik Szczerba, Dr.
ETZ C110 CO-ME/BIWI CH-8092 Zurich
http://www.vision.ee.ethz.ch/~domi