The SceneTreeView sample program imports an FBX file into an empty scene, then displays the scene graph. The scene graph is more precisely a tree, also called a node hierarchy:
The nodes of the tree refer to the contents of the scene, i.e., the cameras, lights, meshes, skeletons, NURBS, etc. that were imported from the FBX file. To display this tree, SceneTreeView must traverse the entire tree, i.e., it must visit each node.