[vtkusers] Volume rendering questions

[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
>
>
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