[vtkusers] Picking points on imageactor

[Beau Sapach]

Hello everyone,

What's the best way to pick points on an imageactor?  I'd like to access the
scalars of the image.  I use vtkCoordinate and pass it
Interactor->GetEventPosition() then use
vtkCoordinate->GetComputedWorldValue()  to pass to vtkPointPicker.  But the
point picker always returns -1.  Is it the z value that's the problem?  I
use 0..... Does the imagedata still have points since imageactor has texture
mapped it?

Beau