Volume rendering questions

[Loris Vosilla]

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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[AGPX]

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Hi,

surely the GPU rendering mode (vtkKWEGPUVolumeRayCastMapper mapper) of the VTKEdge have some problems. I have posted two issues on February (with video), but unfortunately they still are in 'new' status. I hope that these bugs will be removed before the final release will be released (look at: http://public.kitware.com/Bug/view.php?id=8549 and http://public.kitware.com/Bug/view.php?id=8548 for details). In addition to the one posted, I have discovered also a problem similar to your.... that is when I try to fly inside a volume, sometimes it disappears with no reason (I think that most problems are related to the clipping algorithm of the mapper). This is sad because the vtkKWEGPUVolumeRayCastMapper is the volume mapper of VTK/VTKEdge (in speed and quality).

I hope that someone can help...

- AGPX

---

Da: Loris Vosilla <loris.vosilla@...>
A: vtkusers@...; vtkedge@...
Inviato: Ven 6 novembre 2009, 13:45:57
Oggetto: [VtkEdge] Volume rendering questions

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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[Lisa Avila]

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
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the VTK FAQ at: http://www.vtk.org/Wiki/VTK_FAQ
>
> Follow this link to subscribe/unsubscribe:
> http://www.vtk.org/mailman/listinfo/vtkusers
>  

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[AGPX]

Some parts of this message have been removed. Learn more about Nabble's security policy.

Very good news! There's some scheduled date?

---

Da: Lisa Avila <lisa.avila@...>
A: Loris Vosilla <loris.vosilla@...>
Cc: vtkusers@...; vtkedge@...
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
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________

> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the VTK FAQ at: http://www.vtk.org/Wiki/VTK_FAQ
>
> Follow this link to subscribe/unsubscribe:
> http://www.vtk.org/mailman/listinfo/vtkusers
> 
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[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@...> wrote:

Very good news! There's some scheduled date?

---

Da: Lisa Avila <lisa.avila@...>

A: Loris Vosilla <loris.vosilla@...>

Cc: vtkusers@...; vtkedge@...
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
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________

> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the VTK FAQ at: http://www.vtk.org/Wiki/VTK_FAQ
>
> Follow this link to subscribe/unsubscribe:
> http://www.vtk.org/mailman/listinfo/vtkusers
> 

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[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@...> 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@...> wrote:

Very good news! There's some scheduled date?

---

Da: Lisa Avila <lisa.avila@...>

A: Loris Vosilla <loris.vosilla@...>

Cc: vtkusers@...; vtkedge@...
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
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________

> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the VTK FAQ at: http://www.vtk.org/Wiki/VTK_FAQ
>
> Follow this link to subscribe/unsubscribe:
> http://www.vtk.org/mailman/listinfo/vtkusers
> 

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