Thanks a lot for your suggestion!
You are right, depending on the mapper used, lighting differs a lot.
Above, I have used vtkSmartVolumeMapper set with SetRequestedRenderModeToDefault().
when using vtkOpenGLGPUVolumeRayCastMapper or vtkGPUVolumeRayCastMapper instead, the lighting issue is similar.
However, when using vtkSmartVolumeMapper set with SetRequestedRenderModeToRayCast(), the lighting issue is solved, but interactivity is ways slower.
Thanks again!
And thanks for your tip to use/extend 3D Slicer (or TomViz , Paraview or others).
I have thought about it a lot before creating yet another desktop application…
I fear (maybe I am wrong) that I would find it extremely hard to build a 3D Slicer module that would let me interact easily with hundreds vtkPolyData objects at once to produce the examples below :
Here I have interacted with more than 200 vtkpolydata objects (the small cylinders) and placed them interactively in order to be able to 3Dprint the model. It was done quite easily (a couple of hours).
Also, I built a few custom windows and interaction modes to be able to easily 3D tag (color) 3D surface and place many flags (landmarks with caption) on it such as below. Maybe I am wrong, but it may have been hard to do that with a 3D slicer module or Paraview-derived application.
Thanks again!