[vtkusers] How does the vtkGPURayCastVolumeMapper actually work?

[Walmor Cardoso Godoi]

Dear all,

I´m having trouble trying to understand the results I obtained in comparisons between CPU and GPU VTK ray casting.

Machine configuration: Intel(R) Xeon(R) CPU W3680 @ 3.33 GHz 2.79 GHz RAM 24.0 GB, Win 7 64, Video card GTX 580 512 CUDA cores (3 cards in SLI mode).

The results show that GPU are only four times faster than CPU, but why only four times? Shouldn´t the threads be distributed on all cores and therefore shouldn´t we expect a much faster result?

_______________________

Here is the C# CPU code:

//VTK CPU RAY CAST
                vtkVolumeRayCastMapper volumeMapper = vtkVolumeRayCastMapper.New();
                volumeMapper.SetInput((vtkImageData)imData);
                vtkVolumeRayCastCompositeFunction compositeFunction = new vtkVolumeRayCastCompositeFunction();
                volumeMapper.SetVolumeRayCastFunction(compositeFunction);

and here the C# GPU code:

 //VTKGPU RAYCAST
                vtkGPUVolumeRayCastMapper volumeMapper = vtkGPUVolumeRayCastMapper.New();
                volumeMapper.SetBlendModeToComposite();
                //volumeMapper.SetBlendModeToMaximumIntensity();
                //volumeMapper.SetMaxMemoryInBytes(1048576000);
                volumeMapper.SetMaxMemoryFraction(MemoFRACGPU);
                volumeMapper.SetInput((vtkImageData)imData);


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Walmor Cardoso Godoi, DSc
Researcher
Divisão de Materiais - DVMT (Materials Division)
Departamento de Tecnologia em Materiais - DPTM (Department of Materials Technology)
Instituto de Tecnologia para o Desenvolvimento - LACTEC (Institute of Technology for Development)
walmor.godoi at lactec.org.br<mailto:walmor.godoi at lactec.org.br>          www.lactec.org.br<http://www.lactec.org.br/>
Fone (Phone): +55 41 3361-6891  Fax: +55 41 3361-6137



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