(27) Display of a first-person image showing the area of observation at a fixed position in the field of view


(28) Display of a first-person semi-translucent image showing the area of observation in the field of view


(29) Display of an overhead view showing the user position and direction at a fixed position in the field of view 


(30) Display of a 3D CG animation showing the user position and direction, which are superimposed on the corresponding observation position [9]