[vtkusers] Shadow of 2D Actor when using VolumeRayCastCompositeFunction

[David Netherway]

The problem seems not be with an offset of the z buffer image but with the
coarse rendering for interaction.

The projection of the 1 pixel wide 2d actor has a width equal to the coarse
sampling pixel size used for interaction. Sometimes the
last render is left in a coarsely sampled mode and the "shadow" appears.

David

----- Original Message -----
From: "David Netherway" <david.netherway at adelaide.edu.au>
To: <vtkusers at public.kitware.com>
Sent: Monday, February 18, 2002 12:30 PM
Subject: Re: [vtkusers] Shadow of 2D Actor when using
VolumeRayCastCompositeFunction


> If a "renWin Render" is issued through the vtkInteract console the shadow
> goes away.
>
> I am using vtk4 from about  8th or 9th Feb.
>
> Thanks, David
>
> ----- Original Message -----
> From: "David Netherway" <david.netherway at adelaide.edu.au>
> To: <vtkusers at public.kitware.com>
> Sent: Monday, February 18, 2002 12:03 PM
> Subject: [vtkusers] Shadow of 2D Actor when using
> VolumeRayCastCompositeFunction
>
>
> > Hello Vtk Users,
> >
> > On top of my ray cast image I have inserted a cross using 2D actors. But
I
> > get a shadow offset from the cross. See attached sample code. The shadow
> > does not always appear but if you move the volume a few times (say, 5)
you
> > should see the problem.
> >
> > For ray casting with imbedded geometry there is early termination using
> the
> > z buffer. The problem may be related to an image offset between the z
> buffer
> > and the 2D actor position. I have not yet tracked it down. If you turn
off
> > the early ray termination using
> > volumeMapper SetIntermixIntersectingGeometry 0
> >
> > The problem goes away.
> >
> > Does anyone recognise the problem and have a solution?
> >
> > Thanks, David
> >
> >
>
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