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<p class="MsoNormal"><span style="font-family:Consolas;color:#1F497D">The problem is that the surface extraction filter marks all the vertical faces as external because they are all used by just one cell. This leads to all the other issues, including performance
because everything is rendered even if inside.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas;color:#1F497D">I managed to solve the issue for my specific case by employing a StructuredGrid.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas;color:#1F497D">I create an extra column of degenerate cells with zero width at the interface between two columns and I add zero height cells at the bottom if columns have different cell counts.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas;color:#1F497D">This only works because my grid is horizontally structured.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas;color:#1F497D">I don't really like this and I still wonder if there is a general solution for adjacent cells with partially overlapping faces.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas;color:#1F497D">Any thoughts?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas;color:#1F497D">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas;color:#1F497D">Federico<o:p></o:p></span></p>
<p class="MsoNormal"><b><span lang="IT" style="font-size:18.5pt;font-family:"Arial","sans-serif";color:#0093D0;mso-fareast-language:IT"><o:p> </o:p></span></b></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Miorelli, Federico
<br>
<b>Sent:</b> marted́ 16 agosto 2016 17:29<br>
<b>To:</b> 'vtkusers@vtk.org'<br>
<b>Subject:</b> Unstructured grid and coincident face rendering<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-family:Consolas">Dear All,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas">I need to render a 3D grid which is horizontally structured but vertically unstructured (a corner-point grid with vertical pillars).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas">This is made of columns on a regular grid, each column is made up of a possibly different number of voxels whose Z coordinates are different from the neighboring columns. Voxels are displaced only in Z,
so their faces are always perfectly vertical and touch the adjacent columns. <o:p>
</o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-family:Consolas"> *-----*<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-family:Consolas">/ /|<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-family:Consolas">*-----* o-----o<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-family:Consolas">| |/ /|<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-family:Consolas">| o-----o |<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-family:Consolas">| | | |<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-family:Consolas">*-----* | o<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-family:Consolas">| | |/<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-family:Consolas">| o-----o<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-family:Consolas">| |/<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-family:Consolas">*-----*<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas">I am using vtkUnstructuredGrid with VTK_VOXEL cells to represent this. In each column I have (Nz+1)*4 points to represent the voxel edges, so that 4 points are shared between two vertically adjacent voxels.
I cannot share points laterally because the Z values are different.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas">My problem is that I get very bad surface rendering artifacts at the boundaries between two columns, probably because both faces are rendered (see attached screenshot).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas">The only way I could get the correct rendering is by using OSPray in Paraview, but it's very slow on my hardware.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo2"><![if !supportLists]><span style="font-family:Consolas"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-family:Consolas">Is vtkUnstructuredGrid the best way to do this?<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo2"><![if !supportLists]><span style="font-family:Consolas"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-family:Consolas">Is there a way to hint VTK that some faces are partially coincident, as to avoid double rendering?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas">I can provide code samples or data if needed.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas">Thank you for your help,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas">Best Regards<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:Consolas">Federico<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><i><span lang="EN-GB" style="font-size:7.0pt;font-family:"Arial","sans-serif";
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it from your system. Any review, disclosure, copying, distribution, or use of the email by others is strictly prohibited.<o:p></o:p></span></i></p>
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