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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Fellow VTK fans,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I’ve written an app that generates a sequence of
images in a loop, taking progressive slices through a sampled volume of data.
That part is working just fine using a vtkWindowToImageFilter as input to a vtkPNGWriter.
However, when I try to generate a sequence of images alongside that first
sequence, each of which is identical to its corresponding image in the first
sequence except much bigger (this second sequence uses vtkRenderLargeImage,
instead of vtkWindowToImageFilter, as an input to vtkPNGWriter), then the 0th
big image is just fine but all subsequent big images are just the 0<sup>th</sup>
image repeated over again. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I’ve tried lots of variants on this scheme, like using
different objects (vtkPNGWriter, etc.) for each, and hooking them up using SetInput(xxx->SetOutput)
vs. SetInputConnection(xxx->GetOutputPort()) with no change. I’d
appreciate it if someone more familiar with vtkRenderLargeImage could look at
the following – extracted from actual code and adapted to highlight this
specific problem, hopefully without fatal typos or omissions – and tell
me what might be wrong. Thanks very much.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>-Steve<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>// …general C++/VTK setup and boilerplate above
this point<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>pngWriter = vtkPNGWriter::New();<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>windowToImageFilter = vtkWindowToImageFilter::New();<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>bigRender = vtkRenderLargeImage::New();<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>renWin = vtkRenderWindow::New();<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>ren = vtkRenderer::New();<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>char fileName[255];<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>renWin->AddRenderer(ren);<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>renWin->SetSize(640, 480);<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>bigRender->SetInput(ren);<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>bigRender->SetMagnification(5);<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>for (int i = 0; i < numSlices; i++)<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>{<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-indent:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>SetUpNextImage(i); // prepare
the image for rendering. This works fine for small<i>.png.<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-indent:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-indent:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>pngWriter->SetInput(windowToImageFilter->GetOutput());<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-indent:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-indent:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>sprintf(fileName,
“small%d.png”, i);<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-indent:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>pngWriter->SetFileName(fileName);<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-indent:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>windowToImageFilter->SetInput(renWin);<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-indent:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>diskRenWin->Render();<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-indent:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>pngWriter->Write(); //
Beautiful: small<i>.png just as I’d expect.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-indent:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>sprintf(fileName,
“big%d.png”, i);<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> pngWriter->SetInput(bigRender->GetOutput());<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> pngWriter->SetFileName(fileName);<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> pngWriter->Write();
// Uh-oh: every image is just big0.png over again for all i.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>}<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=black face=Geneva><span style='font-size:
10.0pt;font-family:Geneva;color:black'>-Steve Chall<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=black face=Geneva><span style='font-size:
10.0pt;font-family:Geneva;color:black'> Senior Research Software Developer<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=black face=Geneva><span style='font-size:
10.0pt;font-family:Geneva;color:black'> Renaissance Computing Institute<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=black face=Geneva><span style='font-size:
10.0pt;font-family:Geneva;color:black'> Phone: 919-515-0051<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=black face=Geneva><span style='font-size:
10.0pt;font-family:Geneva;color:black'> Email: stevec@renci.org</span></font><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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