[vtkusers] Why is my render slow, rendering in software mode?

[Stefan Wesarg]

Hi Todd,

there are two settings for the rendering quality that dramatically 
influence the render speed - the sample distance and the interpolation 
mode. Decreasing the sample distance or switching from linear to nearest 
neighbor interpolation will increase the rendering performance while 
lowering the render quality. See the following two code snippets:

 >>>>
   // set the corresponding sample distance of the mapper
   vtkVolumeRayCastMapper::SetSampleDistance(SampleDistance);
<<<<


 >>>>
   // set the linear interpolation on or off for the volume properties
   vtkVolumeProperty::SetInterpolationTypeToLinear();
   -- or --
   vtkVolumeProperty::SetInterpolationTypeToNearest();
<<<<

Hope this helps!

Best regards,
Stefan

Todd Gable wrote:

>I made a small program to load some volume data and render it using vtkVolumeRayCastMapper and the rendering is extremely slow. I was also playing with VolView and the rendering and interaction was very fast for the same data. While I was playing with the VolView option I ran into a check box that forced hardware rendering off and the results were very similar to default behavior of my VTK app. After I searched around the only info I could find was that opengl will uses hardware first unless the data format is unsupported. Both VolView and my VTK volume render app are using the same unsigned short .vtk volume data. 
>
>Hardware is a P4 with a 9800 Pro on WinXP.
>
>
>Todd Gable
>
>
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-- 
---------------------------------------------------------------------
Dipl.-Phys. Stefan Wesarg

Fraunhofer Institute for Computer Graphics
Cognitive Computing and Medical Imaging (A7)
Fraunhoferstr. 5, 64283 Darmstadt, Germany
---------------------------------------------------------------------
email:	stefan.wesarg at igd.fraunhofer.de
http://a7www.igd.fhg.de/persons/swesarg/swesarg.html

phone:	+49 6151 - 155 511
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