[vtkusers] volume rendering performance

[Randall Hand]

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
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