Currently qMRMLThreeDView and vtkThreeDViewInteractorStyle share several tasks such as moving the camera and recentering the camera. However, neither has a pointer to the other, and so the logic of actions such as re-centering the camera is duplicated, encouraging bugs. I propose to create a class vtkMRMLThreeDViewLogic which functions analogously to vtkMRMLSliceLogic, and both qMRMLThreeDView and vtkThreeDViewInteractorStyle will have pointers to the same vtkMRMLThreeDView logic and call functions in that class which implement the details of behavior. This will encourage consistent behavior between mouse interaction (qMRMLThreeDView) and keyboard interaction (vtkThreeDViewInteractorStyle)