[vtkusers] Point picking on orthogonal planes

[Rashed Karim]

Hi everyone,

I have 3 orthogonal views through a volume, and using the
Medical3.cxxexample to do this. I have 3 vtkImageActors which display
the three
orthogonal x, y and z slices. Here is some code for the z slice:

vtkImageMapToColors *sliceZColors;
sliceZColors = vtkImageMapToColors::New();
sliceZColors->SetInput(gipl_image);
sliceZColors->SetLookupTable(bwLut);
vtkImageActor *zSlice = vtkImageActor::New();
zSlice->SetInput(sliceZColors->GetOutput());
zSlice->SetDisplayExtent(0, maxX-1, 0, maxY-1, zPos, zPos);

Now the problem is when I am trying to pick a point on the slices using a
vtkPointPicker, the GetPointId( ) functions returns a -1 indicating that no
point was picked. The point picker code is the usual stuff, I create a
picker, set its tolerance, create its callback, add the observer and then
set the picker for the window Interactor. The callback gets called fine when
i press 'p', but picker returns a -1 for point id.

Does anyone have any idea why the picker would return a -1 for point id when
points are picked on a vtkImageActor displaying slices through a volume??

Has anyone tried picking a point on such orthogonal slices through a volume?



Any help will be appreciated,
-- 

Thanks,
Rashed karim
Imperial college London
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