Hi, David,<br><br>Thank you very much for your quick response.<br><br>I'm now studying vtkImageStencil which seems to be able to meet my requirement.<br><br>Cheers,<br><br>Robin<br><br><div class="gmail_quote">On Sat, Sep 19, 2009 at 9:48 PM, David E DeMarle <span dir="ltr"><<a href="mailto:dave.demarle@kitware.com">dave.demarle@kitware.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div>In general the output of this type of operation has to be either vtkUnstructuredGrid or vtkPolyData because when you take an arbitrary subset out of a structured data set you loose the regularity. </div>
<div> </div>
<div>vtkExtractVOI pulls out aligned "slabs" out of structured datasets and because the slabs are aligned in ijk space it's output can stay structured. </div>
<div> </div>
<div>If you have to keep it structured your only option is to create an inside/outside data array. You can threshold on that later if you need to, but again that will produce an unstructured dataset. I think vtkProbeFilter and vtkSampleFunction both can be used to create the "insidedness" array. Others options likely exist too.</div>
<div><br clear="all">David E DeMarle<br>Kitware, Inc.<br>R&D Engineer<br>28 Corporate Drive<br>Clifton Park, NY 12065-8662<br>Phone: 518-371-3971 x109<br><br><br></div>
<div class="gmail_quote"><div><div></div><div class="h5">On Sat, Sep 19, 2009 at 10:13 AM, Robin Zhao <span dir="ltr"><<a href="mailto:zhaoyoubing@gmail.com" target="_blank">zhaoyoubing@gmail.com</a>></span> wrote:<br>
</div></div><blockquote style="border-left: 1px solid rgb(204, 204, 204); margin: 0px 0px 0px 0.8ex; padding-left: 1ex;" class="gmail_quote"><div><div></div><div class="h5">
<div>Hi, Dear vtk guys,</div>
<div> </div>
<div>I met some difficulties on selecting voxels inside a user defined implicit function.</div>
<div> </div>
<div>I have studied vtkExtractGeometry, but its output is unstructured grid.</div>
<div> </div>
<div>I also studied vtkSelection which seems not to support vtkImplicitFunction.</div>
<div> </div>
<div>Are there any possible methods to do it in the framework of vtk, </div>
<div>or do I need to do it by myself.</div>
<div> </div>
<div>Cheers</div><br></div></div>_______________________________________________<br>Powered by <a href="http://www.kitware.com/" target="_blank">www.kitware.com</a><br><br>Visit other Kitware open-source projects at <a href="http://www.kitware.com/opensource/opensource.html" target="_blank">http://www.kitware.com/opensource/opensource.html</a><br>
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<br></blockquote></div><br>
</blockquote></div><br><br clear="all"><br>-- <br>Robin Youbing Zhao(趙友兵)<br>Phone: (+44) 75 0202 1598 (UK)<br> (+86) 135 8571 8767 (中國)<br>Email : <a href="mailto:zhaoyoubing@gmail.com">zhaoyoubing@gmail.com</a><br>
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