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<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>Hi, <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>I am developing a tool to extract VOI (Volume-Of-Interest)
from volumes (</span></font><font size=2 face="Courier New"><span lang=EN-GB
style='font-size:10.0pt;font-family:"Courier New"'>vtkImageData</span></font><font
size=2 face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial'>)
directly in the 3D scene with VTK (5.1.0 version).<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>I’m using </span></font><font size=2
face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>vtkRenderedAreaPicker</span></font><font
size=2 face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial'>
to extract a frustum (a parallelepiped of six faces) from the volume.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>If the six frustum faces are orthogonal to the axes I
can directly crop the volume, simply setting the mapper:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-indent:35.4pt;text-autospace:none'><font size=2
face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>vtkVolumeRayCastMapper
*volumeRaycastMapper = vtkVolumeRayCastMapper::New();<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-indent:35.4pt;text-autospace:none'><font size=2
face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>volumeRaycastMapper->SetCroppingRegionPlanes(bounds);<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'>where bounds are the
(xmin,xmax,ymin,ymax,zmin,zmax) values of the ClipPoints of the picker.<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'>I have problems when the frustum
faces are not orthogonal to the axes. In this case I can use the </span></font><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New"'>vtkExtractSelectedFrustum</span></font><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> class:<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-indent:35.4pt;text-autospace:none'><font size=2
face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>vtkExtractSelectedFrustum
*extractor = vtkExtractSelectedFrustum::New();<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-indent:35.4pt;text-autospace:none'><font size=2
face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>extractor->SetInput(areaPicker->GetDataSet());
// areaPicker is of type vtkRenderedAreaPicker<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-indent:35.4pt;text-autospace:none'><font size=2
face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>extractor->ExactTestOn();<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-indent:35.4pt;text-autospace:none'><font size=2
face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>extractor->SetFrustum(areaPicker->GetFrustum());</span></font><font
size=2 face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial'><o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'>One way is to set:<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-indent:35.4pt;text-autospace:none'><font size=2
face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>extractor->PassThroughOff();<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'>So I have a </span></font><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New"'>vtkUnstructuredGrid</span></font><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> dataset in </span></font><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New"'>extractor->GetOutput()</span></font><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> that contains only the
cells and points of the input that are inside the frustum.<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'>I can render them with a </span></font><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New"'>vtkUnstructuredGridVolumeRayCastMapper</span></font><font
size=2 face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial'>
(but I have to apply a </span></font><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>vtkDataSetTriangleFilter</span></font><font
size=2 face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial'>
before).<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'>In this way after the
rendering process (very very long computation time), to manipulate quickly the
volume, I have to convert the dataset in a </span></font><font size=2
face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>vtkImageData</span></font><font
size=2 face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial'> using
the </span></font><font size=2 face="Courier New"><span lang=EN-GB
style='font-size:10.0pt;font-family:"Courier New"'>vtkWindowToImageFilter</span></font><font
size=2 face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial'>.<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'>This procedure appears to
be too heavy, I’m sure there is another way to do it… a way I’m
still searching for.<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'>I’ve tried also
with the </span></font><code><font size=2 face="Courier New"><span lang=EN-GB
style='font-size:10.0pt'>vtkGaussianSplatter and </span></font></code><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New"'>vtkShepardMethod</span></font><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> to convert the
UnstructuredGrid dataset in a ImageData one, but in using them I loose the
details of the volume, whilst I want simply extract a region of the original
volume (preserving its topology and geometry)..<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'>Any idea?<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'>A second way to do it is
to set:<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-indent:35.4pt;text-autospace:none'><font size=2
face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>extractor->PassThroughOn();<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'>So in </span></font><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New"'>extractor->GetOutput()</span></font><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> I have a </span></font><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New"'>vtkImageData</span></font><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'> dataset that is either a
shallow copy of the input dataset with two new "</span></font><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New"'>vtkInsidedness</span></font><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'>" attribute arrays.<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'>But I don’t know
actually how to set up the </span></font><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>vtkVolumeRayCastMapper</span></font><font
size=2 face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial'>
to render only the cell and the points that are inside the frustum.<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'>I hope this mail could
help someone and I hope someone could help me to continue my work…<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'>Thanks<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial'>Valeria<o:p></o:p></span></font></p>
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