Partially because of the differentiation between visuals and models, the class hierarchy in the System.Windows.Media.Media3D namespace can be a bit confusing. To conclude this chapter, I want to take a stab at sorting out those class hierarchies that you've encountered in this chapter. More class hierarchies will follow in the next several chapters.
You assemble 3D scenes in an element of type Viewport3D, a class that derives directly from FrameworkElement through this long class hierarchy:
Object DispatcherObject (abstract) DependencyObject Visual (abstract) UIElement FrameworkElement Viewport3D