Overview
We are interested in creating
interaction techniques that leverage the unique properties of virtual worlds.
One way to create these techniques is to think about our assumptions about
the real world and how we can break them in a virtual world
.
The Voodoo Dolls technique
is an excellent example of the type of technique we would like to create
by breaking our assumptions. It makes it possible for users to work
with objects at a distance and at widely different scales: users can place
a bumblebee on a flower, and then turn around move their neighbor’s house
to the other side of town.
To accomplish this users
work with dolls. A doll looks like a miniature copy of an object. The user
creates a doll by framing an object with his hand on his image plane and
pinching his fingers together; the system then instantaneously creates
a copy of the object, scales it so that the new doll is a comfortable working
size, and moves the object to the user’s hand.
The action that a doll performs
actually depends on the hand holding it. If the user holds a doll in her
non-dominant hand the doll causes the object represented by the doll to
act as a frame of reference. If the user holds a doll in her dominant hand
the doll controls the position and orientation of the object represented
by the doll. The user moves objects by holding dolls in both her dominant
and non-dominant hands: moving the doll in her dominant hand relative to
the doll in her non-dominant hand causes the object represented by the
doll in her dominant hand to move relative to the object represented by
the doll in her non-dominant hand. When the object is in the desired position,
the user lets go of both dolls to destroy them.
Illustration
The following example illustrates
the Voodoo Dolls technique. Imagine a theatrical director using virtual
reality techniques to experiment with different layouts of set furniture
for a stage play. He is sitting thirty rows back in a virtual theater,
and wants to move a telephone onstage from a desk to a coffee table. If
the director is right handed, he creates a doll for the desk by “grabbing
it” with his left hand. To help provide context, the system creates dolls
for the objects on the desk, which appear on the desk’s doll in the director’s
left hand. With his right hand, the director reaches into the context and
grabs the doll for the telephone. He releases his left hand’s grip, destroying
the desk doll and its context, then creates a doll for the coffee table
with his left hand. He places the telephone doll on the coffee table doll,
and lets go of both. During this process, whenever both his hands are holding
dolls the onstage object represented by the doll in his right hand is positioned
relative to the onstage object represented by the doll in his left hand.
Jeffrey S. Pierce, Brian
C. Stearns, and Randy Pausch. Voodoo Dolls: Seamless Interaction at Multiple
Scales in Virtual Environments. Proceedings of the 1999 Symposium on Interactive
3D Graphics, pages 141-145.
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