mwang@watmath.UUCP (mwang) (11/21/85)
DEPARTMENT OF COMPUTER SCIENCE
UNIVERSITY OF WATERLOO
SEMINAR ACTIVITIES
COMPUTER GRAPHICS SEMINAR
- Friday, November 22, 1985.
Professor William W. Armstrong of the University of
Alberta will speak on ``Solution of Equations of Motion
on a Virtual Tree Machine''.
TIME: 3:30 PM
ROOM: MC 5158
ABSTRACT
The equations of motion of rigid links connected at
hinges to form a tree are formulated in hinge-centered
coordinates and are solved by a method allowing a sig-
nificant amount of parallel processing. This technique
is expected to be useful particularly in computer ani-
mation, where the number of links may be quite large
(say twelve links, at least, for representing a human
being, and many more if deformable surfaces are con-
trolled using ``sensor links''). The computation times
of the usual techniques for solving dynamic equations
of motion may grow as the cube or fourth power of the
number of links, while the new technique requires time
growing only linearly with the depth of the linkage
tree if many processors are used.
The facility on which the technique has been imple-
mented is a multi-computer called the Virtual Tree
Machine. It is running on a network of autonomous VAX
11/780 and SUN-2 computers each under the 4.2BSD UNIX
system.
Background
Dr. William W. Armstrong is a Professor in the Depart-
ment of Computing Science at the University of Alberta.
After obtaining a B.A. in Chemistry at the University
of Saskatchewan, he obtained a Diploma in Mathematics
(sheaf theory & complex manifolds) at Goettingen (West
Germany) and then a Ph.D. in Mathematics (probability
theory) at the University of British Columbia. After
two years as a member of the technical staff at Bell
Laboratories (Holmdel) he returned to Canada, becoming
a professor at the Universite de Montreal where he
stayed until 1982 when he joined the University of
Alberta. His early work involved adaptive logic cir-
cuits and data dependency theory (``Armstrong rela-
tions''). He is currently implementing a new database
model and investigating improvements to the parallel
version of the dynamics program for tree linkages and
applications and computer animation.
Refreshments will be served at 3:00 PM.