Mark R. Mine
Fredrick P. Brooks Jr.
University of North Carolina at Chapel Hill
Carlo H. Sequin
University of California at Berkeley
A Person's sense of the position and orientation of his body and its parts.
World automatically scaled down about user's head every time he grabs an object and scaled back up when he releases it.
Storing of Virtual Objects and Control relative to the User's body.
Menus stored somewhere relative to the Users' body, in a position that aids the user in recalling it's position eg.
Viewing Properties -- stored by the head.
Manipulating Objects -- can be stored by user's hands.
Having a set of widgets to manipulate the object remotely rather than having them on the object(Object Bound Widget)
Hand Held Widgets are preferred over the Object bound widgets due to :
One knows when user's body is in FOV.
Can be used to switch mode between occlusion selection and Ray Casting.
(1) Head Butt Zoom -
Enables a user to switch from global view to local close up view, by moving in and out of a window formed between the two hands of the user.
The position of the window is infront of the user, at the position of his hands.
The zoom factor is dependant on the size of the window made.
The advantages this method provides :
Its utility could be explained in terms of ease of remembering the metaphor, and not using any menu space or buttons .
(1) Virtual Object Docking
Study differences and find out User Preferences between manipulating objects that are co-located with user's hands and objects at a distance.
Similar exercise was carried for 3 different cases, for Object located at the user.s hand position ( scaled grab), then located at a fixed distance ( laser beam interaction) and located at a variable distance (extender grab ).
Target shapes transparent and red in color were to be aligned with opaque blue colored cubes. These blue cubes were either located at User's hand position or at a distance, and then the time taken by the user to align the two cubes was noted.
Each user did 216 trials , ie 36 docking trials /test X 3 tests/block X 2 Blocks
Note : The points are given on the scale of -3 of 3
(2) Virtual Widget Interaction
Find out the difference between using a hand held widget using Proprioception techniques and using a widget system floating in Space. One of the goals was to see to what extent can the user take advantage of this technique.
The Users were expected to carry out a 3 step procedure , once for the hand held widget and then for the widget which was floating in the air , at a fixed distance.
In the case of the hand held widget , the widget moves along with the users hands. In the other case they remain fixed irrespective of the users movements. For both the cases , the Users were supposed to first align a 3D Cursor to one of the 6 spheres on the widget , then align it to an arbitrary object in the space , and finally bring it back to align it with the widget , without any visual feedback.
The positional accuracy of the user , in aligning the cursor was noted , and evaluated.
Experimental Results :
The following table shows the mean positional accuracies in the 2 cases , and the results clearly show , that the hand held widget gave more accuracy in alignment.
These results also indicate the relative preference for Hand Held widget System rather than a widget system away from the body.