[vtkusers] Re: vtkThreshold Question

[Andrea Gavana]

Hello NG,

>It seems to me (if I have read correctly the doc), that vtkExtractCells
>requires a vtkDataSet, a file in other words... is that correct?

Sorry, this is wrong. I supposed it because when I call the method as:

# grid is a vtkUnstructuredGrid

newgrid = vtk.vtkExtractCells(grid)
newgrid.SetCellList(mylist)

it raises an error by saying that input of vtkExtractCells must be a
string... (!!!!!) a string?? Which string? What I have is a
vtkUnstructuredGrid and a list of cell Ids... where should I take that
string?

Thank you for every suggestion..

Andrea.


On 3/31/06, Andrea Gavana <andrea.gavana at gmail.com> wrote:
>
>  Hello Goodwin,
>
>     thank you very much for your help. It seems to me (if I have read
> correctly the doc), that vtkExtractCells requires a vtkDataSet, a file in
> other words... is that correct?
> Well, I already have a vtkUnstructuredGrid built by reading an external
> file (not VTK format). The idea of extracting cells based on Ids implemented
> in vtkExtractCells is very promising... there is nothing similar but without
> using a vtkDataSet?
> The problem is, I should be able to filter out cells by certain criteria:
> for example, at the moment I am trying to exclude inactive cells using this
> ACTNUM, but I would like to be able to filter out the cell based on, i.e.,
> cell centroid depth, cell permeability, cell saturations and so on. This
> seems to me something like a vtkFilter*, and if every time I set up a new
> filter I have to create a file and re-read it I will end up in doing slow
> things. I am too newbie to browse in the right doc places...
>
> Thank you very much for your suggestions.
>
> Andrea.
>
>
>  On 3/31/06, Goodwin Lawlor <goodwin.lawlor at ucd.ie> wrote:
> >
> > Andrea Gavana wrote:
> > > Hello NG,
> > >
> > >     sorry if this question is simple, but I have searched over the web
> >
> > > and I have't found anything close to what I should so. Basically, I
> > have
> > > a vtkUnstructuredGrid in which I set the cell data using some
> > property.
> > > By switching with a wxPython radiobutton I can change on the fly the
> > > property displayed on the grid (like permeability, saturation, cell
> > > centroids and so on). Well, my group of data has also a property
> > called
> > > "ACTNUM", that tells which cells are active (ACTNUM=1) and which are
> > not
> > > active (ACTNUM=0). Active cells should be displayed while inactive
> > cells
> > > should be hidden.
> > > I have succeeded to use vtkThreshold to filter out inactive cells, but
> > > only when I set cell_data=ACTNUM, using something like:
> > >
> > > grid.GetCellData().SetScalars(ACTNUM)
> > >
> > > What I would like to do is, whatever property is displayed on screen,
> > to
> > > hide inactive cells based on ACTNUM value. For example, I would like
> > to
> > > display cell centroids property on the grid filtering out inactive
> > > cells. Something like:
> > >
> > > grid.GetCellData().SetScalars(Whatever)
> > > ??? Apply threshold on grid using ACTNUM ???
> > >
> > > Is there a way to do this?
> > >
> > > Thank you very much for your help and suggestions.
> > >
> > > Andrea.
> > Hi Andrea,
> >
> > You could try vtkExtractCells to filter out cells. You would have to
> > loop through ACTNUM and create the appropriate vtkIdList to apply to the
> >
> > filter. Alternatively, you could try to convert your scalars to RGBA
> > values, where ACTNUM determines the A value (the opacity).
> >
> > hth
> >
> > Goodwin
> >
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>
>
> --
> "Imagination Is The Only Weapon In The War Against Reality."
>
> http://xoomer.virgilio.it/infinity77/
>



--
"Imagination Is The Only Weapon In The War Against Reality."

http://xoomer.virgilio.it/infinity77/
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