GUI system

First of these techniques is one-dimensional (1D) menu [3]. It enables to select one item from limited count. Input can be realized eg. by detecting the change of position or orientation of user's hand, but in this configuration we can use only one degree of freedom. Item is selected when the position/orientation of user's hand is situated in selecting region, which is defined as region bounded by two positions or angles. We emphasize, that the size of selecting region must be such, that we could differentiate safely between separate selecting regions. Considering above criteria, 1D menu has disadvantage in limited count of options/items, which could be handled this way.

If the number of options/items to select grows above reasonable count, then it cannot be fitted within 1D menu. The next logical step is to implement 2D GUI. In two dimensions, we can use all GUI instruments. For selection user's hand positions in 2D plane may be used. This interaction method is analogous to interaction commonly adopted in conventional 2D desktop applications.

The last step is to add the third dimension which brings both power and problems. On the one hand, using 3D GUI allows users to create 3D widgets or sliders, which can be employed for helpful and better manipulation with VE objects. On the other hand, adding the third dimension makes it more difficult for user to interact with 3D GUI.