[vtkusers] Cannot see imagedata behind transparent polydata

Thu Mar 4 04:22:57 EST 2010

Martin,

The solution of using depth peeling doesnt come from me, but from Francois
Bertel, from KitWare.
I dont know how do make depth peeling working with transparent polygons...

Cordialement,

-- Mathieu PICCIN

On Thu, Mar 4, 2010 at 9:31 AM, Martin Allerstorfer <
allerstorfer_martin at gmx.at> wrote:

> But the biggest problem I have at the moment is that I cannot see the
> imagedata behind transparent polygons? Sorry for writting so many questions
> but it is quite urgent for me.
>
> Thank you so much,
> Martin
>
> > I just found out that it works also with imagedata but only for certain
> > distances.
> > If I zoom into the imagedata suddenly polydata is shown behind imagedata,
> > but it should be the other way round.
> > Is there an additional parameter to define the distance where depth
> > peeling starts?
> >
> > Thanks,
> > Martin
> >
> > > Datum: Thu, 04 Mar 2010 08:45:38 +0100
> > > Von: "Martin Allerstorfer" <allerstorfer_martin at gmx.at>
> > > An: vtkusers at vtk.org
> > > Betreff: [vtkusers] Cannot see imagedata behind transparent polydata
> >
> > > Thanks for all the answers! Mathieu, your suggestion using depth
> pealing
> > > works for polydata, but if I want to use imagedata in the same renderer
> > > depth calculation does not work between polydata and imagedata? A
> > solution for
> > > this problem would be great!
> > >
> > > Thanks,
> > > Martin
> > >
> > > >Dealing with non opaque geometry requires sorting the polygon to be
> > > >rendered. It would be extremely slow if it was
> > > >activated by default.
> > > >
> > > >Try to use depth peeling. Follow these steps:
> > > >
> > > >http://www.vtk.org/Wiki/VTK/Depth_Peeling#VTK_calls
> > > >
> > > >You need OpenGL>=2.0 for it to work.
> > > >
> > > >On Wed, Mar 3, 2010 at 12:35 PM, Mathieu P <mtp.vtk at gmail.com>
> > wrote:
> > > >> I have attached a small image illustrating my problem.
> > > >>
> > > >> I cannot believe VTK cannot manage object opacity !
> > > >>
> > > >> Thanks for help.
> > > >>
> > > >>
> > > >> Cordialement,
> > > >>
> > > >> -- Mathieu PICCIN
> > > >>
> > > >>
> > > >>
> > > >>
> > > >> On Wed, Mar 3, 2010 at 4:50 PM, Mathieu P <mtp.vtk at gmail.com>
> > wrote:
> > > >>>
> > > >>> Actually i am using vtkImageActor and i change their opacity with
> > > >>> setOpacity...
> > > >>>
> > > >>>
> > > >>> Cordialement,
> > > >>>
> > > >>> -- Mathieu PICCIN
> > > >>>
> > > >>>
> > > >>>
> > > >>>
> > > >>> On Wed, Mar 3, 2010 at 3:57 PM, Mathieu P <mtp.vtk at gmail.com>
> > > wrote:
> > > >>>>
> > > >>>> Same kind of problem here :
> > > >>>>
> > > >>>> I have two imageData :
> > > >>>>
> > > >>>> Image data A loaded first
> > > >>>> Image data B loaded after
> > > >>>>
> > > >>>> i modify the opacity to 50% for both image data.
> > > >>>> i can see tough the image data B, so the last loaded, but i cannot
> > > see
> > > >>>> toughthe image data A, the first loaded.
> > > >>>> Modifying the opacity of the forst loaded change only its
> > luminosity
> > > (or
> > > >>>> alpha).
> > > >>>>
> > > >>>>
> > > >>>> Cordialement,
> > > >>>>
> > > >>>> -- Mathieu PICCIN
> > > >>>>
> > > >>>>
> > > >>>>
> > > >>>>
> > > >>>> On Wed, Mar 3, 2010 at 3:03 PM, Martin Allerstorfer
> > > >>>> <allerstorfer_martin at gmx.at> wrote:
> > > >>>>>
> > > >>>>> Hi,
> > > >>>>>
> > > >>>>> In my rendering view I would like to show imagedata and
> > additionally
> > > >>>>> some information using transparent glyphs. But not all glyphs
> have
> > > the same
> > > >>>>> transparency. So I change the color and alpha settings for each
> > cell
> > > of the
> > > >>>>> glyphs seperately. Unfortunately now I cannot see the volume
> > behind
> > > the
> > > >>>>> transparent polydata. Does anybody know how to solve this
> problem?
> > > >>>>>
> > > >>>>> Thanks,
> > > >>>>> Martin
> > > >>>>> --
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> > > >>>>>
> > > >>>>> Visit other Kitware open-source projects at
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> > > >>>>>
> > > >>>>> Please keep messages on-topic and check the VTK FAQ at:
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> > > >>>>
> > > >>>
> > > >>
> > > >>
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> > >
> > >
> > > --
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> > > Jetzt freischalten unter http://portal.gmx.net/de/go/maxdome01
> > > _______________________________________________
> > > Powered by www.kitware.com
> > >
> > > Visit other Kitware open-source projects at
> > > http://www.kitware.com/opensource/opensource.html
> > >
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> > >
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>
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>
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