Hi, This is not really a bug, but just what the linear precision integration does. As you can see in vtkIntegrateAttributes.cxx:215, the quad cell is basically cut into two triangles along a diagonal, integration is done for each triangle and the results are added up. So, depending where your "1" falls on a diagonal vertex, you will get different results.
Leo On Sat, Jun 9, 2012 at 8:57 AM, Magician <[email protected]> wrote: > Hi all, > > > Now I found a bug of the filter. > > My ParaView's version is 3.14.1. > I define node names as below: > > c--d > > | | > > a--b > > Case 1: a=1.0, b=0.0, c=0.0, d=0.0 > Integration Value = 0.33333 > > Case 2: a=0.0, b=1.0, c=0.0, d=0.0 > Integration Value = 0.16666 > > Case 3: a=0.0, b=0.0, c=1.0, d=0.0 > Integration Value = 0.16666 > > Case 4: a=0.0, b=0.0, c=0.0, d=1.0 > Integration Value = 0.33333 > > So Integration Values are calculated as (2*a+b+c+2*d)/6. > I think it's not a good result. > > > Magician > > > On 2012/06/08, at 12:54, Magician wrote: > > > Hi all, > > > > > > I'm now comparing integration results of each postprocessors. > > I made a simple Quadratic VTK model as below: > >> # vtk DataFile Version 2.0 > > > >> QuadCell > >> ASCII > >> DATASET UNSTRUCTURED_GRID > >> POINTS 4 FLOAT > >> 0 0 0 > >> 1 0 0 > >> 0 1 0 > >> 1 1 0 > >> CELLS 1 5 > >> 4 0 1 3 2 > >> CELL_TYPES 1 > >> 9 > >> POINT_DATA 4 > >> SCALARS scalar FLOAT 1 > >> LOOKUP_TABLE DEFAULT > >> 0.0 > >> 1.0 > >> 2.0 > >> 4.0 > > > > When I apply Point Data to Cell Data filter, > > scalar values are interpolated as 1.75. > > It may be calculated as (0.0+1.0+2.0+4.0)/4.0. > > > > But when I apply Integrate Variables filter, > > scalar value is integrated as 1.833.... > > The area value of quadratic cell is 1.0, so I thought > > integrated values should be equal to cell data. > > > > How the integrated value is calculated? > > > > > > Magician > > _______________________________________________ > Powered by www.kitware.com > > Visit other Kitware open-source projects at > http://www.kitware.com/opensource/opensource.html > > Please keep messages on-topic and check the ParaView Wiki at: > http://paraview.org/Wiki/ParaView > > Follow this link to subscribe/unsubscribe: > http://www.paraview.org/mailman/listinfo/paraview >
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