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Herman J. Woltring
03-10-1989, 02:14 AM
In reply to Dr Fioretti's posting on WATSMART, his email address on EARN/BITNET/
NETNORTH should be read as FIORETTI%ANVAX2.INFN.IT@ICINECA2. Since the .IT
domain was set up only recently, not all mailing systems might recognize his
address without the ICINECA2 gateway on EARN.

As regards current WATSMART possibilities: it would seem that the system is
being superseded by a system OPTOTRAK with superior accuracy and spatio-
temporal resolution. While WATSMART is based on the Lateral Photodetector
(see, e.g., my paper in the August 1975 issue of the IEEE Transactions on
Electron Devices, or my chapter in H.T.A. Whiting's Human Motor Actions --
Bernstein Reassessed, North Holland, Amsterdam 1984), OPTOTRAK is reputed to
rely on a 2048-element CCD detector in combination with cylindrical optics
and hardware for on-line identification and processing of multiple landmarks.
Thus, the reflection problems for which lateral effect movement monitoring
systems (SELSPOT, IRIS, WATSMART) are notorious seem avoidable in OPTOTRACK.
The system is reputedly twice as expensive as WATSMART, though.

I have seen preliminary data on OPTOTRACK (1987) claiming spatial resolution
of 1:2000 (worst case) to 1:1000 (best case), and temporal resolution of about
100 usec per landmark, irrespective of the number of cameras. Furthermore,
hardware has been announced for real-time rigid-body kinematics at 100 Hz.

Herman J. Woltring, Eindhoven/NL