[vtkusers] [VtkEdge] Volume rendering questions

[Loris Vosilla]

Hello vtkedge users

I solved my problems changing the camera clipping planes
and switching off every light in the scene.  Using these
settings the volumetrical reconstruction works well and is really nice.

Now there are still problems because every now and then the three
dimensional volumetric reconstruction disappears showing a black
image. Then moving the camera a bit the volumetrical reconstructions
appears again.

-Loris

On Tue, Nov 10, 2009 at 5:26 PM, Loris Vosilla <loris.vosilla at gmail.com>wrote:

> 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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