THe Haptics Page

Haptics and Spatial Interaction

In our haptics & spatial interaction work, we use the Phantom(TM)

force feedback device , a three degree-of-freedom mechanical

linkage with a three d.o.f. passive gimbal, which supports a simple

thimble or stylus used by the hand. The Phantom is capable of

reporting the 3D position of the stylus or thimble tip and displaying

force to a person's hand. Using this device, a person can feel

computationally-specified shapes, bulk phenomena, and surface

properties within the work volume.

We are combining force-feedback with holographic stereograms

and holographic video to develop interactive holographic displays

that present vivid coincident visual and haptic cues to a user.

The

haptic holovideo project allows a person to see, "feel", and

interactively modify very simple holographic images, and hints

at how spatial displays with haptic feedback might be used in the

future as design, training, and visualization tools.

In this system, the force model is both spatially and metrically
registered with the free-standing spatial image displayed by
holovideo, and a single multimodal image of a cylinder to be
interactively "carved" is presented. A user can see the hand-held
stylus interacting with the changing holographic image while
feeling forces that result from carving. As the user pushes the
stylus into the simulated cylinder, its haptic model deforms in
a non-volume-conserving way, and a simple surface of revolution
can be fashioned. The simulation behaves as a rudimentary lathe
or potter's wheel.

The haptic model, initially and in
subsequent stages of carving, is
represented as a surface of revolution
with two caps. It rotates about its
vertical axis at one revolution per
second. The model straddles a haptic
plane which spatially corresponds with
the vertical diffuser in the output plane
of holovideo.

Because it is not yet possible to
compute a new 36MB hologram in real
time, we use a set of pre-computed
holograms to "assemble" the visual
representation of the carved surface.
As the holo-haptic image is carved, a
visual approximation to the resulting
surface of revolution is constructed by
loading the appropriate lines from the
set of pre-computed holographic
images.

By making only local line-level changes to the image instead
of recomputing the entire hologram at each visual update, we can
achieve near-real-time update of underlying model geometry
reflected in the holographic display.

Ultimately, the completed model
data can be dispatched to a 3D
printer to produce a physical
hardcopy of the design. The output
shown here was printed on a
Stratasys 3D printer.

Sponsors of this work include the Honda R&D Company, NEC, IBM,
the Digital Life Consortium at the MIT Media Lab, the Office of Naval
Research (Grant N0014-96-11200), the Interval Research Corporation
and Mitsubishi Electric Research Laboratories.

[Selected References]

Ravikanth Pappu and Wendy Plesniak, "Haptic interaction with holographic
video images" Proceedings of the IS&T/SPIE's Symposium on Electronic
Imaging, Practical Holography XII, January 1998.

Wendy Plesniak and Ravikanth Pappu, "Coincident display using haptics
and holographic video" accepted for publication in the Proceedings of ACM
SIGCHI Conference on Human Factors in Computing Systems, April 1998.

Wendy Plesniak and Michael Klug, "Tangible holography: adding synthetic
touch to 3D display," Proceedings of the IS&T/SPIE's Symposium on
Electronic Imaging, S.A. Benton, ed., Practical Holography XI, February
1997.

photos: Webb Chappell and Wendy Plesniak