[vtkusers] [VtkEdge] Volume rendering questions

[Loris Vosilla]

Hello Lisa and vtkusers,
thank for your reply, this is a great news for me as well.

I thought the first problem is due to the way the ray is traced because if
I change the camera to an orthographic projection the problem disappears
(but of course I don't get what I need)

As regard of the second issue I will then use two different renderers in the
two
viewports.
Moreover, looking into slicer 3.x I found several volume rendering mappers
both based on vtk. I would like to ask you what is the difference between
these mappers and vtkKWEVolumeMapper.  Is The difference only related
to the implementation or there is a substantial difference related to the
rendering algorithm ? Where can I find more information on them ?

I'm looking forward to seeing the next vtk release
Thanks
-Loris


On Tue, Nov 10, 2009 at 4:47 PM, AGPX <agpxnet at yahoo.it> wrote:

> Very good news! There's some scheduled date?
>
> ------------------------------
> *Da:* Lisa Avila <lisa.avila at kitware.com>
>
> *A:* Loris Vosilla <loris.vosilla at gmail.com>
> *Cc:* vtkusers at vtk.org; vtkedge at vtkedge.org
> *Inviato:* Mar 10 novembre 2009, 16:25:08
> *Oggetto:* Re: [VtkEdge] [vtkusers] Volume rendering questions
>
> Hello Loris,
>
> The GPU volume ray cast mapper will soon be moving to VTK. At that time we
> will fixing the existing bugs (generally related to the clipping algorithm
> for starting the rays).
>
> As for the second issue - we should add the code to detect this and release
> all graphics resources when we note that the vtkRenderer has changed (and
> hence we have a new view context). The results won't be good - you'll have
> the "slow first render" speed for every render because you'll be alternating
> between two different view contexts (so you will create and reload the
> volume texture twice for every render). So yes, we will fix this bug but no,
> you really should not use this mapper in more than one view content
> (vtkRenderer). In order to do so - we'd need a much bigger VTK-level change
> (sharing of view contexts across renderers).
>
> Lisa
>
>
> Yes - it would be nice to have one copy of the texture and use it in
> multiple vtkRenderers, but that can only be done with a major change to VTK
> to share view contexts across renderers.
>
> Loris Vosilla wrote:
> > Dear Vtk and vtkedge users,
> >
> > I'm using vtkKWEVolumeMapper to volume render a three dimensional blood
> vessel.
> > If I use as rendering mode RayCastAndTexture I don't have any problem,
> but If I use the GPURenderMode I obtain strange resuts:
> >
> > 1) When I draw the volumetrical object with a vtkcamera outside of the
> object self    the rendering works fine, but as soon as the camera enters in
> the volume I can't see    anything.  The opacity function is properly set.
> This problem doesn't come if I use    RayCastAndTexture  drawing method.  If
> needed I can post screenshots of what is    happening.
> >
> > 2) If I want to draw two volumetrical view in two different viewports
> only one is drawn
> >    using GPURenderMode. If I use RayCastAndTexture  drawing method both
> are drawn.
> >
> > Thanks for your help
> > -Loris
> >
> >
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