Hi, The Extract Surface filter will subdivide the quadratic triangles into 4 linear triangles so the resulting field will likely lose some accuracy but not as bad as just going from a quadratic triangle to a linear triangle. I added in a bug for our bug tracker at http://www.paraview.org/Bug/view.php?id=15299 so that gradients can be computed properly for quadratic triangles. I don't have an estimate of when this may get fixed though. If this is urgent enough, this is open-source software so you can try fixing it yourself and sending in a patch. Otherwise, Kitware does provide support contracts for fixing such bugs (see http://www.kitware.eu/products/support.html for more info).
Regards, Andy On Sun, Feb 1, 2015 at 5:30 AM, Eleonora Piersanti < [email protected]> wrote: > Sorry to bother you again. But I need the gradient to make some > verifications in my code. Then, the problem of accuracy is quite important. > Is there any way to compute the gradient without using the Extract surface > filter? > > Kind regards, > Eleonora > > > Il Venerdì 30 Gennaio 2015 11:48, Andy Bauer <[email protected]> > ha scritto: > > > It looks like the Gradient of Unstructured Data Set filter isn't working > properly with quadratic triangles. Try using the Extract Surface filter > before computing gradients to convert them into linear triangles. > > If you want to get more familiar with using ParaView, the ParaView > tutorial at http://www.paraview.org/Wiki/The_ParaView_Tutorial is a good > place to start. > > Regards, > Andy > > On Fri, Jan 30, 2015 at 6:25 AM, Eleonora Piersanti < > [email protected]> wrote: > > Thank you for the answer. > I think that the dimension of the .vtk file was too big. You can download > the .vtk file from: > > > https://www.dropbox.com/s/o1wjo2brsaeu5ag/stability_realEigU_up0.vtk.tar.gz?dl=0 > > In which sense should I use the Slice filter? Sorry but I am quite new > with paraview. > Kind regards, > Eleonora > > Il Venerdì 30 Gennaio 2015 11:16, Eleonora Piersanti < > [email protected]> ha scritto: > > > Thank you, for the answer. > I attach the .vtk file. In which sense should I use the Slice filter? > Sorry but I am quite new with paraview. > Kind regards, > Eleonora > > > Il Venerdì 30 Gennaio 2015 10:59, Andy Bauer <[email protected]> > ha scritto: > > > Your description is a bit vague to diagnose the issue. Can you share your > data set? I was able to use the Wavelet source, use the Slice filter and > then use the Gradient of Unstructured Data Set without any issues. Can you > see if that works for you? > > Regards, > Andy > > On Fri, Jan 30, 2015 at 5:26 AM, Eleonora Piersanti < > [email protected]> wrote: > > Hi to everyone! > I computed with finite elements a 2D velocity field. I plotted without any > problem the velocity field with paraview. I would like to compute the > gradient. > I tried Filters->Gradient of Unstructured Data Set but without succes. > Can you help me? > Thanks, > Nora > > _______________________________________________ > 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 > > Search the list archives at: http://markmail.org/search/?q=ParaView > > Follow this link to subscribe/unsubscribe: > http://public.kitware.com/mailman/listinfo/paraview > > > > > > > > > >
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