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<p class="MsoNormal"><span style="color:#1F497D">I would be interested in a good solution to this, too.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">In 3d Slicer, we’ve been using flying edges filter, which creates usable (non-blocky) surfaces very quickly (suitable for interactive editing). The limitation is that we still need a smoothing filter to avoid
all staircase artifacts, and that it increases update time by about a magnitude.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">We’ve been evaluating using multi-volume rendering for displaying segmentation in 3D, to achieve faster updates and nicer transparent renderings. Multi-volume rendering is good because we can apply Gaussian smoothing
on each input volume to get correctly reconstructed (non-blocky) surface and we can display overlapping segments. However, this Gaussian smoothing takes some time (still competitive with surface smoothing) and multi-volume renderer does not support shading
yet (this is the blocking issue right now).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Andras<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b>From:</b> vtkusers <vtkusers-bounces@public.kitware.com> <b>
On Behalf Of </b>Bertram Sabrowsky-Hirsch<br>
<b>Sent:</b> Thursday, June 7, 2018 3:54 AM<br>
<b>To:</b> vtkusers@vtk.org<br>
<b>Subject:</b> [vtkusers] Smooth label-map volume rendering<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-GB">Hi all,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">I am working with volume data before and after a classification algorithm.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">The input volume has ushort intensity values, the output volume is a label-map where the values indicate each voxels class/label (background=0, vessel=1, aneurysm=2, …).<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">I am visualizing the input volume with a opacity transfer function that simulates a threshold filter (e.g. control points: 799=0.0, 800=1.0) and the result is a nice and smooth visualization of the volume.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">However, the output volume has this blocky Minecraft style effect. The opacity transfer function has the control points: 0=0.0, 1=1.0 and I use the color transfer function to distinguish the classes/labels.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Is there a way to visualize the output volume in a similar way as the input volume? I considered generating iso-surface meshes and smooth those, but this is not really an option. I also don’t really understand why this
is an issue because the<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Input volume is also rendered with a distance of 1 between the two opacity thresholds. Are the volumes handled differently by vtk and how?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Input volume:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-GB"><img width="324" height="286" style="width:3.375in;height:2.9791in" id="Picture_x0020_2" src="cid:image001.jpg@01D3FE56.AEDC44B0"></span><span lang="EN-GB"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Output volume:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-GB"><img width="324" height="304" style="width:3.375in;height:3.1666in" id="Picture_x0020_1" src="cid:image002.jpg@01D3FE56.AEDC44B0"></span><span lang="EN-GB"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Kind regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Bertram<o:p></o:p></span></p>
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