[vtkusers] ExtractVOI with arbitrary shape

[David Gobbi]

Hi Maria,


It is a multistep process, but you can use a pipeline like the
following:

vtkPoints  <-  create your list of points

vtkImplicitSelectionLoop  <- turn the list of points into a function

vtkImplicitFunctionToImageStencil  <- turn function into a stencil (mask)

vtkImageStencil <- apply the stencil to the image

  or

vtkImageAccumulate  <- compute histogram within stencil area, or
                       do image statistics within stencil area

It is also possible to use vtkClipDataSet to clip the image.
This will convert the image into a vtkUnstructuredGrid.

 - David

--
  David Gobbi, MSc                       dgobbi at irus.rri.ca
  Advanced Imaging Research Group
  Robarts Research Institute, University of Western Ontario

On Sun, 23 Jun 2002, Maria Vatshaug Ottermo wrote:

> Hi
>
> I am working on segmentation of an ultrasound volume, and to save
> computation time I want to extract a volume of interest. Until now I have
> been using vtkExtractVOI, but as far as I understand ExtractVOI can only
> be used to extract a rectangular shape. I am using a snake algorithm to
> define the area of interest in each slice of my volume, and the output of
> this algorithm is a linked list. Does anybody know if there is a class in
> vtk that takes a list of coordinates as input instead of a rectangular
> shape?
>
> Thank you!
>
> Maria Ottermo
>
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