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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I think part of my confusion was “point data scalars”.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I initially read that as Scalars of vtkPointData but now I think you are meaning scalar data arrays that represent grid node coordinates.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Is that correct?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Gerrick<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></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:bill.lorensen@gmail.com]
<br>
<b>Sent:</b> Friday, August 02, 2013 3:34 PM<br>
<b>To:</b> Jeff Lee<br>
<b>Cc:</b> Gerrick Bivins; vtkusers@vtk.org<br>
<b>Subject:</b> Re: [vtkusers] algorithm performance<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">You can also compute the scalar data once and use that for cutting. You would need to generate the point data scalars programmaticly. I'm not sure there is a filter to do that.<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><o:p> </o:p></p>
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<p class="MsoNormal">On Fri, Aug 2, 2013 at 4:19 PM, Jeff Lee <<a href="mailto:jlee1549@gmail.com" target="_blank">jlee1549@gmail.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Arial","sans-serif"">The cutter just evaluates the implicit function at every point in the input dataset, then contours that scalar field at the requested value (usually 0). It is equivalent to generating your
own point scalar field of the implicit function on the dataset and running it through a contourfilter, and ScalarTreeOn should produce the speedup of subsequent contour values assuming you are just changing the contour value. For multiple cuts of the same
function you would set multiple values in the filter, that would get you the multiple parallel slice case. The scalar tree won't help if you are changing the implicit function (i.e. the scalar field), but extracting different contour values for a single field
should show improvement. The contour values would be the offset from the zero contour, so values of 0.0, .1, .2, etc.. would generate multiple planes including the original implicit definition.<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><o:p> </o:p></p>
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<p class="MsoNormal">On Fri, Aug 2, 2013 at 4:03 PM, Bill Lorensen <<a href="mailto:bill.lorensen@gmail.com" target="_blank">bill.lorensen@gmail.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">I'll try to find an example that does not use a cut function, but uses the scalar point data. I know I did this years ago when we first wrote vtkCutter and vtkClipPolyData.<o:p></o:p></p>
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<p class="MsoNormal">You should be able to compute point data scalars for your dataset and use those scalars for cutting rtaher than a cut function.<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">At least that is how it used to work.<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><o:p> </o:p></p>
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<p class="MsoNormal">On Fri, Aug 2, 2013 at 3:44 PM, Gerrick Bivins <<a href="mailto:Gerrick.Bivins@halliburton.com" target="_blank">Gerrick.Bivins@halliburton.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Bill,Jeff,</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Currently, the slices will be orthogonal slices, parallel to the Cartesian axes (x,y,z).</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Next request will be multiple arbitrarily oriented slices but probably parallel to each other (same
normal).</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Still absorbing this. It’s not quite clear how I’d generate a planar slice using vtkCutter from the
scalar data. </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Can either of you point me to some example code?
</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Gerrick</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><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""> Jeff Lee [mailto:<a href="mailto:jlee1549@gmail.com" target="_blank">jlee1549@gmail.com</a>]
<br>
<b>Sent:</b> Friday, August 02, 2013 12:01 PM<br>
<b>To:</b> Bill Lorensen<br>
<b>Cc:</b> Gerrick Bivins; <a href="mailto:vtkusers@vtk.org" target="_blank">vtkusers@vtk.org</a></span><o:p></o:p></p>
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<p class="MsoNormal"><br>
<b>Subject:</b> Re: [vtkusers] algorithm performance<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Arial","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...</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:12.0pt"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">On Fri, Aug 2, 2013 at 11:46 AM, Bill Lorensen <<a href="mailto:bill.lorensen@gmail.com" target="_blank">bill.lorensen@gmail.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:12.0pt">Are the slice planes parallel to each other, or are they arbitrarily oriented?<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">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.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:12.0pt"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">On Fri, Aug 2, 2013 at 11:31 AM, Gerrick Bivins <<a href="mailto:Gerrick.Bivins@halliburton.com" target="_blank">Gerrick.Bivins@halliburton.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hi Bill,</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><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.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I’m seeing the behavior in a Paraview install as well,</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">with auto-apply on. Trying to move the slice plane through
</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><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.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><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.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Any other suggestions?</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Gerrick</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><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>]
<br>
<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</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Also be sure you build VTK and your app Release and not Debug.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:12.0pt"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">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:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hi All,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I’m looking for suggestions on how to speed up an algorithm on large unstructured grids, like vtkCutter.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I thought I could build an octree (or similar structure) from the input and execute the vtkCutter on the octree<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">but it’s not obvious to me how to do it. Is something like this possible?<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">How can I improve the speed of the algorithm? Performance seems to go down as cell count grows.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Gerrick<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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