<div dir="ltr"><div style>Sorry for the confusion, it has been a long time since I added that code the DataSetSurfaceFilter. Turning PassThroughCell/PointIds in fact generates a new Ids array, which you can retrieve after the fact to do the lookups into the data that is input to the DSF and extract particular cells/points by their offset (n'th cell in the cell array, n'th point in the point array)</div>
<div style><br></div><div style>However I still recommend making your own ids array and using that instead of PassThrough. vtkIdFilter will generate them for you. The array marked as the active global ids array is treated specially by most filters in that they try to preserve it across operations (including threshold and DSF). We added this to VTK a few years ago specifically for this case of finding out where particular result values come from (and in particular for surface selection). So the Threshold and surface filter will push globalIDS forward just fine. Once you get a result, grab the active globaIDs array, look for the values in it, and look them up in the original data. The extract selections filter will do the job of looking them up in the original data and pulling them out as a new dataset.</div>
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<div><br></div></div><div class="gmail_extra"><br clear="all"><div>David E DeMarle<br>Kitware, Inc.<br>R&D Engineer<br>21 Corporate Drive<br>Clifton Park, NY 12065-8662<br>Phone: <a href="tel:518-881-4909" value="+15188814909" target="_blank">518-881-4909</a></div>
<br><br><div class="gmail_quote">On Wed, Mar 6, 2013 at 10:02 AM, Bhanu Hariharan <span dir="ltr"><<a href="mailto:bhanu@petrotel.com" target="_blank">bhanu@petrotel.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
David,<br>Thanks for replying. However I have a doubt.<br>Are you suggesting the VTKUnstructuredgrid should have an globalids array? Is that what the member is called - globalIds? I actually pass VTKUnstructuredgrid to a VTKThreshold filter and then pass that filter to VTKdatasetsurfacefilter.<br>
<br>Perhaps you can post a couple lines of code. That would be very helpful.<br>Thanks,<br>Bhanu<div><div><br><br><br><div class="gmail_quote">On Tue, Mar 5, 2013 at 6:55 PM, David E DeMarle <span dir="ltr"><<a href="mailto:dave.demarle@kitware.com" target="_blank">dave.demarle@kitware.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><p>The input data should have a globalids array containing a unique value for each cell. If it does, extract will preserve it. After the extraction, use that array in the polydata to do the look up to the original cell in the unstructured grid.</p>
<div class="gmail_quote"><div><div>On Mar 5, 2013 6:00 PM, "Bhanu Hariharan" <<a href="mailto:bhanu@petrotel.com" target="_blank">bhanu@petrotel.com</a>> wrote:<br type="attribution"></div></div>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div>
Hi All,<br><br>I need some help doing the following. Please could one of you guide me on how.<br><br>I use a vtkDataSetSurfaceFilter on VTKUnstructuredGrid to render skin of that grid. That works fine and I can see the number of surfaces shown by grabbing the <br>
dataSetSurfaceFilter->GetOutput()->GetNumberOfCells().<br><br><br>I need a way to map the surface back to the original cell id. That is if I have 2 cells and I render just skin, number of surfaces rendered are 10. I need to be able to pick on any of these 10 surfaces and map them back to either of the the 2 grid cells.<br>
<br><br><a href="http://www.vtk.org/doc" target="_blank">http://www.vtk.org/doc</a> says :<br><br>If PassThroughCellIdsOn is 1, then the output polygonal dataset will have a celldata array that holds the
cell index of the original 3D cell that produced each output cell. This
is useful for cell picking.<br>I turned the PassThroughCellIds On and I have UseStrips turned off.<br><br>Then I did<br>vtkPolyData *surfacePolyData = dataSetSurfaceFilter->GetOutput();<br><br>But I do not see how I can access that celldata array that holds the original 3D cells for the surfaces.<br>
<br>Please can anyone advise on how.<br><br>Thanks in advance.<br>Bhanu<br><br><br><br><br><br>
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