[vtkusers] PCA on vtkImageData
david.gobbi at gmail.com
Mon Nov 17 11:40:46 EST 2014
It should export all the points in the volume, as long as they are within
the applied thresholds. What is your evidence that it's only exporting the
On Mon, Nov 17, 2014 at 9:34 AM, Andrew Crozier <
andrew.crozier at medunigraz.at> wrote:
> Hi David,
> Thanks for the suggestion. I looked at the vtkThreshold filer, however it
> appears to export the boundary of the thresholded volume, whereas I require
> all points inside the volume. Have you any idea of how to achieve that?
> On 17/11/14 17:16, David Gobbi wrote:
> Hi Andrew,
> The vtkThreshold filter will extract only the cells with the desired
> scalar values, and will output them as an unstructured grid. It
> isn't exactly what you want because it extracts cells, rather than
> points, but it might be worth a shot.
> - David
> On Mon, Nov 17, 2014 at 8:28 AM, Andrew Crozier <
> andrew.crozier at medunigraz.at> wrote:
>> I am trying to evaluate the principal components of a strucutre in a 3D
>> volume image, to determine its spatial alignment for use in an automatic
>> processing pipeline.
>> The input is a vtkImageData, with multiple integer values (say, 0, 1, 2
>> and 3), and I want to perform PCA on the positions of all voxels with value
>> 2, for example.
>> I have looked at vtkPCAAnalysisFilter, and this requires an input of
>> vtkPointSet. vtkImageDataToPointSet converts a vtkImageData to a
>> vtkStructuredGrid, however I expect this to include all points in the
>> original image. At the moment I seem to be missing some way of filtering
>> out the points other than those of value 2.
>> Any help provided for this would be greatly appreciated!
>> Best wishes,
>> Andrew Crozier
> *Andrew Crozier*
> andrew.crozier at medunigraz.at
> Postdoctoral Researcher
> Institute for Biophysics
> Medical University of Graz
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