<DIV>Hi Ken, Thank you for your input. I am using VTK4.4 official release. I will try the CVS version</DIV>
<DIV>soon. vtkUnstructuredGridVolumeRayCastMapper is just too slow and difficult to interact with.</DIV>
<DIV>The example IntermixedUnstructuredGrid.tcl can show it all. Another problem is that many</DIV>
<DIV>imaging processing classes such as vtkImagePlaneWidget won't accept vtkStructuredGrid</DIV>
<DIV>data but vtkImageData only.</DIV>
<DIV> </DIV>
<DIV>I really want to transform my irregularly shaped unstructured volume data into the </DIV>
<DIV>vtkImageData so I can use all powerful image filters. vtkShepardMethod is definitely one</DIV>
<DIV>solution. The problem is that vtkShepardMethod generates data in the region where no </DIV>
<DIV>original data is available. SetNullValue and SetMaximumDistance may solve the problem</DIV>
<DIV>partially but not entirely. Is there any other way to go?</DIV>
<DIV> </DIV>
<DIV>Thanks.</DIV>
<DIV> </DIV>
<DIV>Jim</DIV>
<DIV><BR><BR><B><I>"Moreland, Kenneth" <kmorel@sandia.gov></I></B> wrote:</DIV>
<BLOCKQUOTE class=replbq style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid">
<META content="MSHTML 6.00.2800.1491" name=GENERATOR>
<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>
<BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #800000 2px solid; MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<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>
<HR SIZE=1>
Do you Yahoo!?<BR>Yahoo! Small Business - <A href="http://us.rd.yahoo.com/evt=31637/*http://smallbusiness.yahoo.com/resources/">Try our new resources site!</A> </BLOCKQUOTE></BLOCKQUOTE><p>
<hr size=1>Do you Yahoo!?<br>
Yahoo! Small Business - <a href="http://us.rd.yahoo.com/evt=31637/*http://smallbusiness.yahoo.com/resources/">Try our new resources site!</a>