A haptically-augmented interface for digital character animation

彬彬

1 Introduction

The majority of the commercially available software are accessed

through the Windows/Icon/Mouse/Pointer (WIMP) interfaces. Arguably,

these interfaces fail to communicate the richness and complexity

of human gesture [Scali et al. 2003]. Consequently, embodied

skills such as those of creative makers cannot be easily accommodated

in digital workspaces. In [Dima et al. 2010] we illustrated

this issue in the traditional technique of puppet Stop-motion Animation

and, as a first step, explored how puppet stop-motion animators

perceive a virtual workspace mounted with the haptic modality and

enabling gestural action. The investigation was driven by the development

of a new interface system for animating digital 3-D articulated

characters designed in collaboration with puppet Stop-motion

animators. Hereby, we present further insights on the perception of

the virtual workspace derived from the design study on bi-manual

interaction. The system itself contributes a new interaction mechanism

in the field of Human-Computer Interaction.

2 System Design

The virtual workspace was a 2 1=2D space on the computer screen

mounted with a set of backgrounds and models which could be selected

from a drop down menu. A skeleton (or rig), a hierarchical

chain of bones and joints, was attached to each virtual character

making its movement possible via the implementation of kinematic

algorithms. An on-screen animation controller provided information

about each captured frame and keyboard buttons were used to

set/advance/retrace/swap and delete a frame as well as save or load

a sequence of frames.

One 6-DoF stylus-based haptic device, Sensable Omni, was used

to manipulate the whole or parts of the virtual character’s skeleton

as well as the lights and cameras. The device was represented on

screen with a sphere which could be moved in three dimensions

within the virtual workspace. For the bi-manual interaction study

we used two input devices for the actions of the non-dominant hand

which were initially assigned to moving the camera: the Wii controller

and Connexxion’sTM3D mouse . We tested various setups

for the Wii. In the most preferable one, the animators would hold

the Wii vertically to the ground. The Wii transfered mimetically to

the camera viewpoint the animators’ gestures which corresponded

to tilting, spinning and rolling, moving up and down. Moving back

e-mail: marizadima@ed.ac.uk

ye-mail:mark.wright@ed.ac.uk

ze-mail:john.lee@ed.ac.uk

and forth, right and left was done by pressing the cross buttons. By

pressing the back button the camera would stop moving. A keyboard

button positioned the camera in close distance to the character

and keeping button ’A’ on the Wii pressed would put it in orbit

around it. Using this setup, we asked a team of three stop-motion

animators to manipulate and animate an articulated 3-D character

with no specific time limitations in order to explore how they

perceived the virtual environment through haptically-augmented bimanual

work.

3 Results

In [Dima et al. 2010] we discussed the difficulty the animators had

in perceiving the virtual space in relation to how they moved the

haptic device’s representation in it. We explored the solution of

providing visual cues (e.g. visual markers on the selected bones)

which led to the observation that visual and haptic cues provide

greater perception of space and ease its navigation. The bi-manual

interaction study revealed ways of improving their perception of the

space kinaesthetically.

Although the Wii was considered to be a less static device in comparison

to the 3D mouse, the animators would prefer neither of the

two for camera manipulation. They suggested that this task could

be carried out with the haptic controller in the dominant hand using

the device’s buttons on the stylus to switch between camera navigation

and character manipulation. The controllers, and particularly

the Wii, could instead be used to move or rotate the whole character

while the dominant hand would use the haptic device to perform

the subtle manipulation of the character’s skeleton parts. We found

that this method improved their perception of the virtual space as

opposed to having both hands working in different things without

being co-located, even roughly, on the virtual space. In addition, the

animators occasionally felt that the sense of touch that the device

recreated assisted them in navigating around the skeleton’s structure

and in understanding the position of the device’s representation

during navigation.

References

DIMA, M., WRIGHT, M., AND LEE, J. 2010. Exploration of direct

bi-manual interaction in digitally mediated stop-motion animation.

In Proceedings of NordiCHI 2010, NordiCHI 2010.

SCALI, S., WRIGHT, M., AND SHILLITO, A. M. 2003. 3d modelling

is not for wimps. In Proceedings of HCI International,

HCI International.

tc

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