[Paraview] choppy derivatives

[Peter Brady]

Fantastic!  "InputBlock" is a leaf block as suspected.

Until my next question,
Peter

On Thu, Apr 22, 2010 at 5:15 PM, Berk Geveci <berk.geveci at kitware.com>wrote:

> You have to get the leaf nodes of the multi-block dataset first. In
> this case, I suspect inputBlock will be a leaf block.
>
> -berk
>
> On Thu, Apr 22, 2010 at 5:01 PM, Peter Brady <petertbrady at gmail.com>
> wrote:
> > The location we're looking at is the interface between two fluids so
> there
> > may be a discontinuity in the tangential derivatives for that reason.
> I'm
> > trying to write my own derivative and interpolation filters in a python
> > programmable filter which will take  one-sided derivatives and use
> one-sided
> > interpolation.  In order to do this I need to use cell data in my filter
> and
> > not point data to avoid the interpolation that takes place.  Typically I
> > access point data with something like:
> >
> >> input = self.GetInputDataObject(0, 0)
> >> output = self.GetOutputDataObject(0)
> >>
> >> inputBlock = input.GetBlock(0)
> >> # copy old data
> >> output.CopyStructure(input)
> >> outputBlock = inputBlock.NewInstance()
> >> outputBlock.UnRegister(None)
> >> outputBlock.CopyStructure(inputBlock)
> >> output.SetBlock(0,outputBlock)
> >>
> >> # get number of points
> >> numPts = input.GetNumberOfPoints()
> >> # temperature gradient
> >> GtArr = input.GetPointData().GetVectors('ScalarGradient')
> >
> > However, there doesn't seem to be an equivalent 'GetNumberOfCells()' or
> > 'GetCellData()' for my multiblock data.  How can I access the cell data?
> >
> > Thanks for your help,
> >
> > Peter.
> >
> > On Tue, Mar 30, 2010 at 10:15 AM, Berk Geveci <berk.geveci at kitware.com>
> > wrote:
> >>
> >> I wonder if this is because of the multiple celldata -> point data
> >> conversions. Do you have an example dataset you can share?
> >>
> >> On Sun, Mar 28, 2010 at 1:45 AM, Peter Brady <petertbrady at gmail.com>
> >> wrote:
> >> > Hello list,
> >> >
> >> > I have a 3D dataset with a Temperature field.  My goal is to insert a
> >> > sphere
> >> > source and determine the tangential temperature gradient on the
> surface
> >> > of
> >> > the sphere at various zenith angles.  The data is output from the code
> >> > as
> >> > cell data.  Here is the way I'm doing this (through pvpython)
> >> >
> >> > 1.  Apply CellDataToPointData
> >> > 2.  Apply ComputeDerivatives (to get the 'Scalar Gradient')
> >> > 3.  Apply another CellDataToPointData (to turn the derivatives into
> >> > point
> >> > data)
> >> > 4.  Resample the data from step 3 with my sphere source.
> >> > 5.  Use a programmable filter to combine the xyz derivatives
> >> > appropriately.
> >> >
> >> > The data is reasonable but it's fairly choppy.  When I look at dT/dx,
> >> > dT/dy,
> >> > and dT/dz (before I project them onto the sphere surface), and plot
> them
> >> > at
> >> > a particular zenith angle around the azimuth of the drop, dTdx and
> dTdy
> >> > are
> >> > very smooth but dT/dz is fairly choppy (especially above the equator
> of
> >> > the
> >> > drop).  If I expand my sphere to a place where there's not a lot going
> >> > on
> >> > dT/dz seems to calm down.  Is there a way to smooth dT/dz in the
> >> > location of
> >> > interest or should I try to write my own derivatives filter to make
> them
> >> > smoother?  Any thoughts?
> >> >
> >> > Thanks,
> >> > Peter.
> >> >
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>
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