<div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">IIRC the unstructured grid algorithm doesn't use a cell locator to find candidate cells, it runs over all cells and checks the scalar range of the cell and then contours it if the range is satisfied. Its faster than blindly contouring every cell but not as good as it could be. A better approach would be to use a scalar tree (where the function value is the scalar) and use that to locate candidate cells. It will be expensive to build the tree the first time, but subsequent contours of the same function will typically be much faster, as the candidate cells have been sorted in bins by range in the scalar tree. You would have to modify the algorithm a bit to do this, but i've had success with that approach in the past...</div>
</div><div class="gmail_extra"><br><br><div class="gmail_quote">On Fri, Aug 2, 2013 at 11:46 AM, Bill Lorensen <span dir="ltr"><<a href="mailto:bill.lorensen@gmail.com" target="_blank">bill.lorensen@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>Are the slice planes parallel to each other, or are they arbitrarily oriented?<br><br></div>If they are parallel, then you could compute point data scalars once and leave out the implicit function. Then Cutter will use the scalar data for cutting. This would avoid recomputing the scalar field for each slice.<br>
<div><br></div></div><div class="HOEnZb"><div class="h5"><div class="gmail_extra"><br><br><div class="gmail_quote">On Fri, Aug 2, 2013 at 11:31 AM, Gerrick Bivins <span dir="ltr"><<a href="mailto:Gerrick.Bivins@halliburton.com" target="_blank">Gerrick.Bivins@halliburton.com</a>></span> wrote:<br>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Hi Bill,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">We are building release. Our grids are large at least 10’s – 100’s of thousands of cells.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I’m seeing the behavior in a Paraview install as well,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">with auto-apply on. Trying to move the slice plane through
<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">the dataset becomes less and less interactive as the dataset cell count increases.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">So I was hoping there were some ways to speed this up.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Any other suggestions?<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Gerrick<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<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""> Bill Lorensen [mailto:<a href="mailto:bill.lorensen@gmail.com" target="_blank">bill.lorensen@gmail.com</a>]
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<b>Sent:</b> Friday, August 02, 2013 10:18 AM<br>
<b>To:</b> Gerrick Bivins<br>
<b>Cc:</b> <a href="mailto:vtkusers@vtk.org" target="_blank">vtkusers@vtk.org</a><br>
<b>Subject:</b> Re: [vtkusers] algorithm performance<u></u><u></u></span></p><div><div>
<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">Also be sure you build VTK and your app Release and not Debug.<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><u></u> <u></u></p>
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<p class="MsoNormal">On Fri, Aug 2, 2013 at 11:08 AM, Gerrick Bivins <<a href="mailto:Gerrick.Bivins@halliburton.com" target="_blank">Gerrick.Bivins@halliburton.com</a>> wrote:<u></u><u></u></p>
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<p class="MsoNormal">Hi All,<u></u><u></u></p>
<p class="MsoNormal">I’m looking for suggestions on how to speed up an algorithm on large unstructured grids, like vtkCutter.<u></u><u></u></p>
<p class="MsoNormal">I thought I could build an octree (or similar structure) from the input and execute the vtkCutter on the octree<u></u><u></u></p>
<p class="MsoNormal">but it’s not obvious to me how to do it. Is something like this possible?<u></u><u></u></p>
<p class="MsoNormal">How can I improve the speed of the algorithm? Performance seems to go down as cell count grows.<u></u><u></u></p>
<p class="MsoNormal">Gerrick<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p>
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