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<DIV dir=ltr align=left><SPAN class=613532320-14042005><FONT face="Courier New"
color=#800000 size=2>1) Pretty soon (in the next week or two) I plan to
check in a projected tetrahedra mapper. That should be faster, but of
lower image quality. Of course, if you are not using the CVS version of
VTK, that will not help for quite a while.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=613532320-14042005><FONT face="Courier New"
color=#800000 size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=613532320-14042005><FONT face="Courier New"
color=#800000 size=2>2) Hmm, that "wireframe" artifact looks like a bad ray
integration. Are you using VTK 4.4 or the CVS version? The
integration has gotten much better since the last VTK
release.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=613532320-14042005><FONT face="Courier New"
color=#800000 size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=613532320-14042005><FONT face="Courier New"
color=#800000 size=2>Those artifacts can be made less pronounced by making the
transfer function less opaque and/or making the colors change more slowly.
If that area where the volume changes from yellow to red is interesting, you may
want to consider putting a red isosurface there and then render a yellow volume
around that. The result will probably look quite pleasing and may speed up
the rendering a bit.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=613532320-14042005><FONT face="Courier New"
color=#800000 size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=613532320-14042005><FONT face="Courier New"
color=#800000 size=2>3) Your suggestion of sampling the volume to an image is
viable. That was what many people did before
vtkUnstructuredGridVolumeRayCastMapper was around (which was not very long
ago). I never did it, so I can't offer any details. Maybe someone
else can chime in.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=613532320-14042005><FONT face="Courier New"
color=#800000 size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=613532320-14042005><FONT face="Courier New"
color=#800000 size=2>-Ken</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=613532320-14042005><FONT face="Courier New"
color=#800000 size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=613532320-14042005><!-- Converted from text/plain format -->
<P><FONT face="Courier New" color=#800000 size=2>
**** Kenneth Moreland<BR>
*** Sandia National
Laboratories<BR>*********** <BR>*** *** *** email:
kmorel@sandia.gov<BR>** *** ** phone: (505)
844-8919<BR> ***
fax: (505) 845-0833<BR></FONT></P></SPAN></DIV><BR>
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<FONT face=Tahoma size=2><B>From:</B> vtkusers-bounces@vtk.org
[mailto:vtkusers-bounces@vtk.org] <B>On Behalf Of </B>jiksed<BR><B>Sent:</B>
Thursday, April 14, 2005 1:19 PM<BR><B>To:</B>
vtkusers@vtk.org<BR><B>Subject:</B> [vtkusers] Any alternative to
vtkUnstructuredGridVolumeRayCastMapper<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV>
<DIV>
<DIV>
<DIV>
<DIV>
<DIV>Hi vtkusers,</DIV>
<DIV> </DIV>
<DIV>I have a 3D volume data in an unstructured grid with irregular surface
topography. My first</DIV>
<DIV> instinct is to use vtkUnstructuredGridVolumeRayCastMapper to do the
volume rendering. The</DIV>
<DIV> problem is that this volume mapper is extremely slow and the
wireframe-type mesh is visible </DIV>
<DIV>in the volume image (please see the attachment). My questions would
be:</DIV>
<DIV> </DIV>
<DIV>1) Is there any way to speed it up? </DIV>
<DIV>2) How can I make the image more smooth without showing the underline
wireframe?</DIV>
<DIV>3) Is there any alternative to vtkUnstructuredGridVolumeRayCastMapper? I
really need an </DIV>
<DIV>ImageData so I may manipulate the volume opacity and use the
ImagePlaneWidget.</DIV>
<DIV> </DIV>
<DIV>One way I can think of is to use vtkShepardMethod to transform
vtkUnstructuredGrid into </DIV>
<DIV>vtkImageData in a rectangular box. My data is inside an irregular volume
like human head. </DIV>
<DIV>Now how do I "get rid of" excessive volume to expose my irregular surface
topography? How </DIV>
<DIV>do I manipulate the output of vtkShepardMethod? By setting a small
MaximumDistance, some </DIV>
<DIV>points may end up with NullValues but not those points close to the outer
surface of my data </DIV>
<DIV>volume. I am kind of lost here. </DIV>
<DIV> </DIV>
<DIV>Thank you for any suggestions.</DIV></DIV></DIV></DIV></DIV></DIV>
<P>
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