[vtkusers] problem with vtkPicker

[Nadine Kempe]

Hi at all,

I am working on the extension of an environment  for visualization and analysis of 3D SPECT data. As I am not the original author of the code I have some trouble understanding the problem which occurs to  me now:

I have vtkKWRenderWidgets which holds some vtkImageData (3D SPECT, so there are only voxels with different values for their color). The user can klick on each of the voxels and the program tells him the value at this specific point. This is realized with a vtkPicker (from vtkWindowInteractor) and it's method GetPickPosition().  So each time I click in there, I get the coordinates of the point. The problem: when you zoom in, for some voxels these coordinates change. That means when I click on one point, then zoom in and click on the same point again, these two pairs of coordinate are not exactly the same (only for some voxels). This leads to the problem, that I get different values for the same point, depending on the zoom.


I hope my English is understandable and somebody can give me a hint, help is really appreciated!

My best regards,
Nadine
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