[vtkusers] vtkGPUVolumeRayCastMapper Fails

[Sergio Aguirre]

links to images here

spacing-camera-noauto-1X -
http://dl.dropbox.com/u/8559744/spacing-camera-noauto-1x.jpg

spacing-camera-auto -
http://dl.dropbox.com/u/8559744/spacing-camera-auto.jpg

normal - http://dl.dropbox.com/u/8559744/normal.jpg

fixed-additive - http://dl.dropbox.com/u/8559744/fixed-additive.jpg



On Mon, Jan 23, 2012 at 8:25 PM, Sergio Aguirre <sergio.aguirre at gmail.com>wrote:

> Hi everyone
>
> I am trying to render some DICOM volumes using vtkGPUolumeRayCastMapper
> however it fails and I get the following message:
>
> " render clipped 1 ERROR (x501) Invalid value
> Assertion failed: "pre: valid_current_reduction_range" &&
> this->ReductionFactor>
> 0.0 && this->ReductionFactor<=1.0, file
> ..\..\vtk-5.8.0\VolumeRendering\vtkOpenG
> LGPUVolumeRayCastMapper.cxx, line 3906 "
>
> I believe this is a problem caused by my pipeline set up. I have a
> requirement to have the following camera configuration:
>
> vtkSmartPointer<vtkCamera> cam = vtkSmartPointer<vtkCamera>::New();
> cam->SetPosition(0.0, 0.345, 0.222); // set position to display offset
> cam->SetFocalPoint(0.0, 0.0, 0.0); // set cam LookAt
> cam->SetViewUp(0.0, 1.0, 0.0); // set View up
>
> Since the camera is looking at a fixed area in space, I need to scale my
> DICOM images to fit in this space - I do this in ITK using a filter called
> itkChangeInformationImageFilter. The result is that each voxel has "real"
> size and spacing (e.g. if the dicom tags say that X,Y spacing is 0.625mm
> and Z spacing is 1mm then this filter allows me to import voxels of
> 0.000625, 0.000625, 0.001 size or smaller.
>
> My configuration of the vtkGPUolumeRayCastMapper is as follows:
> dcmMapper->SetMaxMemoryInBytes(536870912);
> dcmMapper->SetMaxMemoryFraction(0.80); // trigger GPU
> dcmMapper->SetAutoAdjustSampleDistances(0); // no adjust sample distance
> dcmMapper->SetImageSampleDistance(0.5);
> dcmMapper->SetInput(dcmVImage);
> dcmMapper->SetBlendModeToComposite();
>
> The above configuration fails.
>
> I tested other configurations with the following results:
>
> 1 - With SetAutoAdjustSampleDistances(0), SetImageSampleDistances(1.0) the
> image is "ghostly-flat" = "spacing-camera-noauto-1x.jpg"
> 2 - With SetAutoAdjustSampleDistances(1), only higher density values are
> rendered = "Spacing-camera-auto.jpg"
>
> What I would like to have as a rendered image is the attached image
> "normal.jpg" which I rendered with SetAutoAdjustSampleDistances(1) and no
> settings on my camera or re-sizing of the images in ITK.
>
> I can achieve the desired output with vtkFixedPointVolumeRayCastMapper
> (see "fixed-additive.jpg") using "additive" blending - but I would rather
> use the video card for volume rendering.
>
> Is this something I can fix or maybe repair modifying some code of
> vtkOpenGLGPUVolumeRayCastMapper? or do I need a larger video card? I am
> using a Quadro FX 3700
>
> Any suggestions are appreciated.
>
> Thank you,
>
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