[vtkusers] volume rendering performance

[flin at enders.tch.harvard.edu]

Sorry for taking me so long to get back to this.

I tried FixedPointRayCastMapper and VolumeTextureMapper3D. I didn't see
much improvement with FixedPoint, could that because I don't have dual
processors?  or is there something I missed?
With VolumeTextureMapper3D, the speed is twice as fast as the
RayCastMapper, however, it seems only working for certain type of data ( I
created a sphere and a block, only the sphere shows up with 3d texture).
Does anyone have some explanation for that?

Thanks.

/faith


> That's really interesting, for me the ProjectedTetra was so time consuming
> I
> ended up rendering only one slice of my volume so I could at least see
> some
> output. I do have many variations in opacity, my dataset is of a chest (I
> don't have much 'dead' space around the organs), so it sounds like this
> may
> really be a bad use of ProjectedTetra.
>
> All my output is interactive, fixed point/3d texture have been pretty
> decent
> when it comes to responsiveness, except if the camera moves too close to
> the
> volume. The ray cast mapper looks the 'nicest' but it really takes too
> long
> to be used interactively for me. I was hoping that the responsiveness of
> ProjectedTetra would be good once ready for display, but it actually had
> the
> worst interactivity out of the bunch, even with one slice. Besides the
> opacity issue, I believe the ray cast mapper etc have built in functions
> to
> reduce the quality of the rendering while the user is interacting, which
> is
> very nice.
>
> Thanks for sharing your experience,
> Mark
>
>
>
>
> On 2/7/06, Randall Hand <randall.hand at gmail.com> wrote:
>>
>> The last dataset I used was a 512-cube, stored as a vtkImageData I
>> believe.  One thing that greatly effects rendering time is the level of
>> opacity you have.  in my case, I had large regions of the space that
>> were
>> going to be completely transparent (accumulated opacity = 0.0), with
>> only
>> a small fireball in the center to render.  If I adjusted my transfer
>> function so that larger regions were rendered, then the render time
>> increased.
>>
>> Using a fixed transfer function that rendered only the small portion of
>> the dataset I wanted to see, the FixedPoint mapper was abysmal at about
>> 30
>> minutes per frame, and the ProjectedTetra mapper works in about 6
>> minutes
>> (with the DataSetTriangleFilter time included).  All of my stuff is
>> non-interactive, being dumped directly to PNG images on disk.
>>
>> On 2/7/06, Mark Wyszomierski <markww at gmail.com> wrote:
>> >
>> > Hi Randall, Faith,
>> >
>> > I gave vtkProjectedTetrahedraMapper a try for the first time today but
>> I
>> > experienced the longest render times with it out of any of the other
>> > mappers. I'm wondering what your input data being rendered is? Mine is
>> a
>> > vtkImageData volume with dimensions of 256x256x56. The fixed point
>> mapper or
>> > 3d texture mapper give me the fastest results.
>> >
>> > Mark
>> >
>> >  On 2/6/06, Randall Hand <randall.hand at gmail.com > wrote:
>> > >
>> > > I think the best results will actually come from using the
>> > > vtkProjectedTetrahedraMapper -
>> > > http://www.vtk.org/doc/release/5.0/html/a01919.html
>> > >
>> > > I've pretty much tried them all.  The vtkVolumeRayCastMapper took
>> > > about an hour to generate an image for me, the
>> vtkFixedPointRayCastMapper
>> > > cut it down to about 30 minutes.  The vtkProjectedTetrahedraMapper
>> takes the
>> > > cake, however, at a whopping 5 minutes.  Unfortunately, it does take
>> alot
>> > > more memory as it requires you to "tetrahedralize" your mesh.
>> > >
>> > > On 2/6/06, flin at enders.tch.harvard.edu <flin at enders.tch.harvard.edu
>> >
>> > > wrote:
>> > > >
>> > > > Hello all,
>> > > >
>> > > > I need some advice on how much imporvement the
>> > > > vtkFixedPointVolumeRayCastMapper will make vs. regular
>> > > > vtkVolumeRayCastMapper ?  I'm doing volume rendering of roughly
>> > > > 250x80x150 voxels, and the speed is unacceptable.   Any
>> suggestions
>> > > > on how
>> > > > to speed up?  Specifically, how to use hardware to accelerate it?
>> > > >
>> > > > Thanks.
>> > > >
>> > > > /faith
>> > > >
>> > > >
>> > > > _______________________________________________
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>> > >
>> > >
>> > >
>> > > --
>> > > Randall Hand
>> > > Visualization Scientist,
>> > > ERDC-MSRC Vicksburg, MS
>> > > Homepage: http://www.yeraze.com
>> > > _______________________________________________
>> > > This is the private VTK discussion list.
>> > > Please keep messages on-topic. Check the FAQ at:
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>> > >
>> > >
>> >
>>
>>
>> --
>> Randall Hand
>> Visualization Scientist,
>> ERDC-MSRC Vicksburg, MS
>> Homepage: http://www.yeraze.com
>>
>