Lathe combines a force image of a simple cylindrical stock with

        a holographic video image of the same geometry. An interacting

          person can see, feel, and carve the multi-modal simulation
        into an arbitrary rotationally-symmetric shape. The final shape
        can be dispatched to a 3D printer to generate hardcopy.
          - overview
          - touch
          - poke
wendy plesniak &   
ravikanth pappu   
  Lathe has three subsystems: the haptics  
module, the holovideo module, and the
model manager. The haptics module runs
our force simulation and drives the force-
feedback device. The holovideo module
precomputes holograms, and drives rapid
local updates on the holovideo display.
The model manager keeps the visual and
haptic representations in sync.
The force simulation runs at an average
servo rate of 5kHz, and the holovideo
update rate is 10fps. The system operates
with 1s of lag between haptic and hologram
updates. Thus, typically, as a person lathes,
the surface is immediately felt to change
and seen to change a second later.
  Lathe achieves near-real-time holovideo updates by
using a set of precomputed holograms of cylindrical
stocks having different radii. The final image is
then assembled from appropriate regions of this
precomputed hologram set, and only changed in
regions where the model has been affected by a
person's carving. By making line-level changes, we
avoid recomputing the entire 36MB holographic
fringe pattern at each update.
Using such specific precomputed elements permits
only a limited set of images to be assembled. Our
third holo-haptic experiment, Poke, addresses
this problem by using more generalized precomputed
fringes to assemble a more arbitrary final image.
The force model is given by a 1D
NURB curve which sweeps out
a surface of revolution. Pressing
into the model with the Phantom
stylus causes a force to be displayed
back to the hand; pressing with
enough force causes model control
points to be displaced inward and
the stock deforms uniformly
around its circumference.
Finally, the completed model data
can be dispatched to a 3D printer to
produce a physical hardcopy of the
carved design. The model shown to
the right was printed on a Stratasys
3D printer. The entire process serves
as one example of a future design
and prototyping pipeline.
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",
Proceedings of ACM SGICHI Conference on Human Factors in Computing Systems, April 1998.
Wendy Plesniak and Ravikanth Pappu, "Spatial interaction with haptic holograms", Proceedings of
the IEEE International Conference on Multimedia Computing and Systems (ICMCS'99), June 1999.
Wendy Plesniak and Ravikanth Pappu, "Tangible, dynamic holographic images", in Kuo, C.J. (Ed.),
3-D Holographic Imaging. Wiley-Interscience (invited, in press).
Sponsors of this work include Honda R&D Company,
NEC, IBM, the Digital Life Consortium at the MIT
Media Laboratory, the Office of Naval Research
(Grant N0014-96-11200), Interval Research Corporation,
and Mitsubishi Electric Research Laboratories.
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