[vtkusers] What Is Wrong With My VTK Pipeline ?

[Amy Squillacote]

Hi Mark,

>From the header file for the vtkHAVSVolumeMapper:

// vtkHAVSVolumeMapper is a class that renders polygonal data
// (represented as an unstructured grid) using the Hardware-Assisted
// Visibility Sorting (HAVS) algorithm.

The vtkHAVSVolumeMapper is a hardware-based algorithm, so not all
graphics cards will support it. Regardless, it operates on
vtkUnstructuredGrid datasets, not vtkImageData. It is possible to
convert vtkImageData to vtkUnstructuredGrid, but it is not recommended
that you do that just to volume render your data. Representing
vtkImageData as a vtkUnstructuredGrid requires much more memory that
leaving it in its original format. If you want to use a
hardware-accelerated volume rendering method for your vtkImageData, try
vtkVolumeTextureMapper3D.

- Amy

JohnMark wrote:
> thank you for your suggestion , Amy ,
> but from the user guide , we can see there is a subclass of
> vtkUnstructuredGridVolumeMapper :
> vtkHAVSVolumeMapper , and it can work for vtkImageData , although it
> would need some help from the
> hardware . so , should I think that vtkUnstructuredGridVolumeMapper
> can not take vtkImageData as input
> ports , even though you make some transformation ?
> or in other words , when I do my volume rendering , and my input ports
> are the objects of
> vtkImageData , I should use the subclasses of vtkVolumeMapper instead of
> vtkUnstructuredGridVolumeMapper ? is there any method to do volume
> rendering with vtkImageData ( or
> the readers of .dcm images )and the subclasses of
> vtkUnstructuredGridVolumeMapper ? what should I do
> now ?
>
> thank you for your help again !
>
> Mark
>
>
>
>
>
> ------------------------------------------------------------------------
>
> > Date: Wed, 19 Sep 2007 08:14:53 -0400
> > From: amy.squillacote at kitware.com
> > To: zhaojunxp at hotmail.com
> > CC: vtkusers at vtk.org
> > Subject: Re: [vtkusers] What Is Wrong With My VTK Pipeline ?
> >
> > Hi Mark,
> >
> > vtkImageMandelbrotSource does not take any inputs, regardless of the
> > dataset type of the input. Looking in the constructor for that class,
> > the last line is the following.
> >
> > this->SetNumberOfInputPorts(0);
> >
> > That means that even though one of the superclasses of
> > vtkImageMandelbrotSource (vtkAlgorithm, specifically) has a
> > SetInputConnection method, it is ignored by the class you're using.
> >
> > If you want to volume render the dataset output from vtkVolume16Reader,
> > use one of the subclasses of vtkVolumeMapper, not
> > vtkUnstructuredGridVolumeMapper. The subclasses of vtkVolumeMapper work
> > for vtkImageData, which the output of vtkVolume16Reader is.
> >
> > - Amy
> >
>
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-- 
Amy Squillacote
Kitware, Inc.
28 Corporate Drive
Clifton Park, NY 12065
Phone: (518) 371-3971 x106