I’m sorry if I didn’t understand very well, if we play with the opacity we suppose that there are already 2 actors on inside the other? isn’t, it isn’t my case, I have a VTK head (just a head there is no VTK brain inside),
I need to peel some parts of the VTK head (I will calculate the parts to remove by using the VTI volume where we can see the head and the brain inside and a value of depth to peel (the user gives it using a silder) ) so when we silde the silder to a point where we arrive to the brain (in the VTI), the VTK head takes the form of the VTI