[vtkusers] volume rendering performance

Wylie, Brian bnwylie at sandia.gov
Thu Feb 16 17:52:16 EST 2006 

All,

The vtkProjectedTetrahedraMapper is for unstructured data and using it
on structured data is not going to work well (that obviously is an
understatement :)

  Brian Wylie - Org 9227
  Sandia National Laboratories
  MS 0822 - Building 880/A1-J
  (505)844-2238 FAX(505)845-0833                       
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> -----Original Message-----
> From: vtkusers-bounces+bnwylie=sandia.gov at vtk.org 
> [mailto:vtkusers-bounces+bnwylie=sandia.gov at vtk.org] On 
> Behalf Of flin at enders.tch.harvard.edu
> Sent: Thursday, February 16, 2006 2:18 PM
> To: Mark Wyszomierski
> Cc: vtkusers at vtk.org
> Subject: Re: [vtkusers] volume rendering performance
> 
> 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
> >> > > >
> >> > > >
> >> > > > _______________________________________________
> >> > > > This is the private VTK discussion list.
> >> > > > Please keep messages on-topic. Check the FAQ at:
> >> http://www.vtk.org/Wiki/VTK_FAQ
> >> > > >
> >> > > > Follow this link to subscribe/unsubscribe:
> >> > > > http://www.vtk.org/mailman/listinfo/vtkusers
> >> > > >
> >> > >
> >> > >
> >> > >
> >> > > --
> >> > > 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:
> >> > > http://www.vtk.org/Wiki/VTK_FAQ
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> >> > >
> >> > >
> >> > >
> >> >
> >>
> >>
> >> --
> >> Randall Hand
> >> Visualization Scientist,
> >> ERDC-MSRC Vicksburg, MS
> >> Homepage: http://www.yeraze.com
> >>
> >
> 
> 
> 
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