17-03-2014, 06:18 PM
ABSTRACT
Manipulation in immersive Virtual Environments (VEs) is often difficult
and inaccurate because humans have difficulty in performing
precise positioning tasks or in keeping the hand motionless in a
particular position without any help of external devices or haptic
feedback. To address this problem, we propose a set of four manipulation
points attached to objects (called a 3-Point++ tool, including
three handle points and their barycenter), by which users can
control and adjust the position of objects precisely. By determining
the relative position between the 3-Point++ tool and the objects,
and by defining different states of each manipulation point (called
locked/unlocked or inactive/active), these points can be freely configured
to be adaptable and flexible to enable users to manipulate
objects of varying sizes in many kinds of positioning scenarios.
Keywords: 3D Direct Manipulation, Virtual Environments
1 INTRODUCTION
Object position and orientation manipulation are among the most
fundamental and important interactions between humans and environments
in VR applications. Many approaches have been developed
to maximize the performance and the usability of 3D manipulation.
However, each manipulation metaphor has its own limitations
and cannot be generally used in a broad variety of VEs. We
are especially interested in precise manipulation of large objects in
VEs. This task is usually difficult because of user’s view obstruction
caused by the size of objects during their positioning stages [2].
It is more difficult when the user has to place large objects with required
precision. Some approaches [6, 7, 8] have been proposed to
manipulate objects at a distance by creating their miniature models
or by expanding the user’s virtual arm. These propositions have
an advantage for large objects manipulation: when the user has an
overall view of objects or of environment, it is easier for him to
know how to move these objects to the target position and orientation
without worrying about obstruction problems. However, their
main issue is that small movements of the miniature models or of
the user’s virtual hand from a distance are often magnified in the environment,
making precise positioning difficult. A reasonable distance,
at which the size of objects is not too disturbing and the user
can still determine where to place them, is hardly found sometimes.
Some approaches have been proposed to manipulate objects
more precisely and efficiently. PRISM [3] proposes a dynamical adjustment
method which determines the relationship between physical
hand movements and the controlled object motion, making it
less sensitive to the user’s hand movements. However, the user
may feel a sense of incompatibility because of the difference between
the visual feedback and motor control. Osawa [5] proposes a
technique adding a viewpoint adjustment stage to enlarge the scene
when the hand grasping the virtual object is moving slowly. Nevertheless,
this adjustment may influence the user’s immersion and
may cause fatigue when the user manipulates large objects. In addi-
e-mail: thi-thuong-huyen.nguyen[at]inria.fr
†e-mail: thierry.duval[at]irisa.fr
Figure 1: The handle point P2 is manipulated, the object is rotated
around an axis created by the two handle points P1 and P3
tion, there is no orientation manipulation in this technique, it means
that it is incomplete for object manipulation in general. Precise
manipulation is also often required in assembly modeling systems
through constraint-based manipulation. These systems usually demand
knowledge-based descriptions to be integrated in advance
into a constrained behavior manager [4]. This manager realizes assembly
relationship recognition, constraint solving and constrained
motion. It can improve the precision of manipulation but it is quite
complicated to apply them in the general case of manipulation.
The 3-hand manipulation technique [1] may facilitate the 3D manipulation
by determining the position of objects through the position
of three non-aligned manipulation points on a plane. However,
this technique is mainly devoted to multi-user collaborative manipulation
and it is quite difficult for one user to manipulate objects. In
this paper, we want to enhance this technique for a general purpose
of manipulating objects of varying sizes, especially large objects,
in many kinds of positioning scenarios.
Manipulation in immersive Virtual Environments (VEs) is often difficult
and inaccurate because humans have difficulty in performing
precise positioning tasks or in keeping the hand motionless in a
particular position without any help of external devices or haptic
feedback. To address this problem, we propose a set of four manipulation
points attached to objects (called a 3-Point++ tool, including
three handle points and their barycenter), by which users can
control and adjust the position of objects precisely. By determining
the relative position between the 3-Point++ tool and the objects,
and by defining different states of each manipulation point (called
locked/unlocked or inactive/active), these points can be freely configured
to be adaptable and flexible to enable users to manipulate
objects of varying sizes in many kinds of positioning scenarios.
Keywords: 3D Direct Manipulation, Virtual Environments
1 INTRODUCTION
Object position and orientation manipulation are among the most
fundamental and important interactions between humans and environments
in VR applications. Many approaches have been developed
to maximize the performance and the usability of 3D manipulation.
However, each manipulation metaphor has its own limitations
and cannot be generally used in a broad variety of VEs. We
are especially interested in precise manipulation of large objects in
VEs. This task is usually difficult because of user’s view obstruction
caused by the size of objects during their positioning stages [2].
It is more difficult when the user has to place large objects with required
precision. Some approaches [6, 7, 8] have been proposed to
manipulate objects at a distance by creating their miniature models
or by expanding the user’s virtual arm. These propositions have
an advantage for large objects manipulation: when the user has an
overall view of objects or of environment, it is easier for him to
know how to move these objects to the target position and orientation
without worrying about obstruction problems. However, their
main issue is that small movements of the miniature models or of
the user’s virtual hand from a distance are often magnified in the environment,
making precise positioning difficult. A reasonable distance,
at which the size of objects is not too disturbing and the user
can still determine where to place them, is hardly found sometimes.
Some approaches have been proposed to manipulate objects
more precisely and efficiently. PRISM [3] proposes a dynamical adjustment
method which determines the relationship between physical
hand movements and the controlled object motion, making it
less sensitive to the user’s hand movements. However, the user
may feel a sense of incompatibility because of the difference between
the visual feedback and motor control. Osawa [5] proposes a
technique adding a viewpoint adjustment stage to enlarge the scene
when the hand grasping the virtual object is moving slowly. Nevertheless,
this adjustment may influence the user’s immersion and
may cause fatigue when the user manipulates large objects. In addi-
e-mail: thi-thuong-huyen.nguyen[at]inria.fr
†e-mail: thierry.duval[at]irisa.fr
Figure 1: The handle point P2 is manipulated, the object is rotated
around an axis created by the two handle points P1 and P3
tion, there is no orientation manipulation in this technique, it means
that it is incomplete for object manipulation in general. Precise
manipulation is also often required in assembly modeling systems
through constraint-based manipulation. These systems usually demand
knowledge-based descriptions to be integrated in advance
into a constrained behavior manager [4]. This manager realizes assembly
relationship recognition, constraint solving and constrained
motion. It can improve the precision of manipulation but it is quite
complicated to apply them in the general case of manipulation.
The 3-hand manipulation technique [1] may facilitate the 3D manipulation
by determining the position of objects through the position
of three non-aligned manipulation points on a plane. However,
this technique is mainly devoted to multi-user collaborative manipulation
and it is quite difficult for one user to manipulate objects. In
this paper, we want to enhance this technique for a general purpose
of manipulating objects of varying sizes, especially large objects,
in many kinds of positioning scenarios.