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Yue-nan Jenp
12-30-1993, 01:15 AM
On December 14, '93 I posted the following request:

> I Have a budget to purchase a 6-camera optical tracking system to
> set up a gait lab.. Could I have opions about the pros and cons of
> Vicon 370 and MAC HiRes from anyone who had the experience on
> either system?

Since some people asked me to foreward the replies I received, I'll post
them as followed:

From: Fong-Chin Su, Ph. D.
Dear Dr. Jenp:
It's quite good to let motion analysis companies compete with each
other, then you get the best deal. Also, you are smart to organize a
committee to make the final decision. In my mind, my students will vote
Hi-Res ExpertVision, but I don't know what system Prof Chou prefers.
Because the decision philosophy is quite different between the "new" and
"old" generation.
In my opinion, I prefer Hi-Res ExpertVison because it supports
GX script language suitable for custom developement and becomes user
friendly. Also, it has several well-developed packages for clinical
applications, OthoTrack, KinTrack..etc. For clinical gait analysis,
OtroTrack has all required functions. Wu Hong-Wen told me that Vicon's
package is still under developing i.e. some function shown on the
pull-down-menu doesn't exist yet. For VICON, Wu Hong-Wen told me that
64 K memory will be required for 32 analog and video collection.
So far, MS windows still is not real multitasking, multiusers system.
For SUN workstation, it is real multitasking, multiusers system.
During collecting data (experiment), other people still can use the
SUN workstion through network. Unix is becoming popular and popular.
Its commands are very similar to DOS. It is worthwhile to learning
it. The email system at NCKU which you are using is SUN workstation.

>From Robert Neal, PhD
I have written a response to Neil Glossop on my experience with the
MAC and you are welcome to ask him for this info. He is compliling a
document that contains opinions of various people. I should point out
that we did not purchase the HiRes system (ours was a little earlier).

>From Dr. Peter G. Kropf
Here is a collection of some messages recently posted on Biomech-l
regarding imaging. I would be interested in answers you get to your request.
Could you send me a collection of tose later on.
--------- Begin Forwarded Message ----------
We have a Panasonic (National) AG-7350 VCR with an RS-232C add-on
which allows us to operate the VCR from a microcomputer. We are
especially interested in taking advantage of the time code
generator to control our digitising of videotape.
The product manual is quite helpful, but it lacks sufficient
information to do all the things we want. I suspect it is a
translation from its original language as well.
Are any of our readers famililar with this issue? Can anyone
suggest a source of 'generic' subroutines, perferably in BASIC or
Turbo Pascal, which can help us to get up to speed here? Any and
all suggestions gratefully accepted (and any pertinent info will
be posted here as a summary)...............Drew Smith PhD

It was very nice to see your latest posting about VCR, because I
think you may be able to help me in a problem which seems to have
a solution but difficult to decode from all the technical and
commercial jargon.
My problem is that I want to be able to record the patient's
gait , from multiple views if possible, display these recordings
on different windows on the screen, overlay graphics, i.e.
graphical representations of measured parameters such as
forces/moments, on each window and on each "Frame", and finaly
store these on a VCR to enable repeated examinaton of the
patient's analysis by clicians.
I am faced with the problem of real time digitisation of video
frames which means no PC will be fast enough to store the
digitised frames at 25 Hz. The other problem would be to record
the modified images, i.e. those with the graphics, onto a VCR at
25 Hz (i.e. real time rate). Apparently it is not possible to DAC
a digitised frame for writing to VCR fast enough (i.e. at a rate
of 25 Hz). the only option is therefore to stop/pause or freeze
the VCR at individual frame positions to allow the computer to
DAC the frame.
IS this possible ?
By the sound of your question sent to the list it seems that you
have experiences in this area which you might be willing to
share.
..Hamid Rassoulian Senior Medical Engineer Southampton
General Hospital U.K.

Do you have the pages from Panasonic for their 'computer
control codes'? If you have the codes to drive the serial port
with, then the programming of the VCR is quite trivial, depending
on how fancy you want to get.
We bought an AG6750 (time lapse VCR) and it took some fairly
forceful persuasion to squeeze the info out of Panasonic. You
should have someone handy who understands Japanese. A lot of the
technical info is half-and-half English and Japanese.
For an application this off the track, I think you're being
overly optimistic about getting hold of 'generic' software.
Is your time code generator a SMPTE VITC type? Can you access
single fields with your VCR? Are you digitizing from video at the
normal playback rate, or digitizing from stopped motion?
If your time code is SMPTE and you are digitizing at the normal
frame rate, I doubt if you need much programmability, since you
can trigger the digitizer from a SMPTE reader.
If you are using SMPTE, I'd be curious where you got this stuff
from (and how much) since a year or two ago when we looked into
this type of data collection, most video houses were abysmally
ignorant of the technique. Since then we have been using Optotrak
hardware, and the setup is MUCH easier, 10-15 minutes as compared
with 3-4 hours for 3D video. Since I can 'genlock' the Optotrak
with a video sync signal, it behaves much as a video camera,
except giving us on-line 3D accurate coordinate data.
We have a number of programs to handle video data, to correct
for tilt barrelling etc,to track missing markers, to manually fix
botched data. They are all in 'Microsoft C (v7.0)'. Non of the
programs actually digitize directly from the VCR - even with a
time base corrector, the quality was too low or the sync to rough
to get good coordinates. The system we have (the old video one)
would be accurate to a few millimetres in a 2m X 3m view.
Are you building a system from the ground up, or are you tying
this system into a commercial unit? -Paul

I don't have any knowledge of the Panasonic AG 7350 VCR, but I
have written some programs to control a Panasonic AG 1960 VCR
from a PC. This had to be done via an editor as the 1960 does not
have a serial port.
Currently we use a SMPTE time code generator to dub time code on
the audio track and/or put a time code "window" on the video
tape. The programs I've written are in "C".
If you have any general questions with regard to this type of
programming, feel free to contact me.
...........Brett Lee Purdue University brettlee@purccvm.bitnet

I've just read your letter to BIOMCH-L about programming
a AG-7350. We have exactly the same model VCR with the RS-232
add-on which we use with an eye-movement monitoring system, and
we connect the VCR to an IBM compatible computer (80286). I know
what you mean abuot the documentation; it took me a long-long
time re-reading it to get some sort of handle on it. I written a
few program using turbo-c and they seem to work OK. There are a
few things about the system that don't seem quite right, like
I've never found out a simple command to do a single field step
but I get around that problem OK. Also, it seems that I can only
get the time-base control to talk in terms of frames rather than
individual fields. I can certainly give you a more complete
picture of how we use the system, and some example programs to
drive the VCR. If you want to mail me and give me a better idea
of what you want to do I'll get back to you, or latter on today I
can chase up some listing for you and email them (the problem
being that I have on ever written them for my own use so the
inline documentation is not to good.
...Ross Kummer Technical Officer, Royal Melbourne Institute of
Technology, Melbourne, Australia. Internet address
RKUMMER@PITVAX.XX.RMIT.EDU.AU

We have a lot of experience with programming video cassette
recorders, video timecode readers, tape controllers, etc. We have
developed a "Video Tape Analysis System", which includes software
support for a wide range of professional VCRs, including the
Panasonic AG-7350 with AG-IA232TC interface. However, since this
is a commercial product, we cannot distribute the source code of
the software routines which control the VCR and timecode
hardware. I am not aware of any general public-domain libraries
that serve your purpose.

We would be happy to send you information about our software
products, but that may not be what you are looking for. Please
don't think that all we want is sell you a product - we are also
eager to share technical experiences.
I hope that this is of any help for you....Lucas P.J.J. Noldus, Ph.D.

In a message of 28 Nov 93 A.W. Smith wrote to Alle:
The product manual is quite helpful, but it lacks sufficient information
to
Do you have a list of codes, that the vcr accepts?
of 'generic' subroutines, perferably in BASIC or Turbo Pascal, which
You `only` need some IO subroutines for the RS-232 for output of
the vcr-control-sequences. I don`t have such subroutines, but I
think, you could find this in some ftp-sites.
any pertinent info will be posted here as a summary).
Thanks, I`m interested in the command-list for the vcr.
.................................................. ....................MfG, Christian

Dear subscribers:
Here is the summary of the responses to my request of the video
resources. I am very grateful to all individuals who spent their
precious time to provide me with valuable resources.
My e-mail address--yxk109@psuvm--will be not in use any more as
of August 9. I will let you know my new address soon.
Young-Hoo Kwon
[SUMMARY]

I. FRAME GRABBERS

Data Translation, Inc.
100 Locke Drive
Marlboro, MA 01752-1192
USA
Phone: 508-481-3700
US Sales: 800-525-8528
FAX: 508-481-8620

DT2851 (B&W) & DT3851 (Color) series


MATROX Electronic Systems
1055 St. Regis Blvd.
Dorval, Quebec
Canada H9P-2T4
Fax: (514) 685-6066
Phone: (514) 685-7230

PIP series

Coreco, Inc.
6969 Trans-Canada Hwy, Suite 113
St-Laurent, Canada H4T 1V8
Phone: 514-333-3100
Technical Support: (514) 333-7190
Fax: (514) 333-1388

Occulus series

Others
New Media Graphics
Phone: 800-288-2207
Redlake
Phone: 408-779-6464
Univision
Phone: 617-221-6700
Imaging Tecnology, Inc.
600 West Cummings Park
Woburn, MA 01891-6343
Phone: 617-938-8444
Fax: 617-938-1757
Dipix Technologies
1050 Baxter Road
Ottawa, Ontario
Canada
Infrascan Inc.
Phone: (604) 273-8655
Fax: (604) 278-3423

II. VIDEO CONTROLLER or VIDEO EDIT CONTROLLER

BCD Associates, Inc.
7510 N. Broadwat, Suite 205
Oklahoma City, OK 73116
Phone: 405-843-4574
Fax: 405-840-3147

BCD Video Tape Control System

Future Video edit controller (714-770-4416)

III. COMMERCIAL SYSTEMS

Northern Digital (Optotrak)

Peak Performance Technologies, Inc. (Video Motion
Measurement System)
7388 S. Revere Parkway, Suite 601
Englewood, Colorado, 80112
Phone: 303-799-8686
FAX: 303-799-8690

IV. RESOURCES

Biewener, A. and Full, R.J. Force plattform and kinematic
analyis.
In: Biomechanics. Structures and Systems. A practical
approach.
(Ed. by A. Biewener). Oxford University Press.
--some recommendations about image acquisiton and data
analysis

Myler and Weeks. Computer Imaging Recipes in C,
Prentice-Hall, 1993
ISBN 0-13-189879-5

V. STRATEGIES OF IMAGE GRABBING SUGGESTED

A. FIELD-BY-FIELD GRABBING on pause mode

* Put VCR on pause -> grab image (field) -> either
store image in
the hard disk (w/ compression) or direct
digitizing
* Requires time-base corrector & synch pulse generator
integrated
VCR to grab a stable video image from the VCR on
PAUSE mode
* Ariel System uses similar strategy.
* Time base corrector: a device which strips off the
unstable video
synch pulse and adds a new stable one
* Manual field advance

B. FRAME-BY-FRAME GRABBING

* Grab video image frame by frame.
* Split each frame into odd and even field:
interpolation is
required for the missing lines.
* Peak System uses this approach.
* Automatic frame advance with computer controllable
VCR (RS232
interface) or VCR + video controller board
----------- End Forwarded Message -----------

>From Mark Redfern
Dear Dr. Jenp,
Could you post the responses you get on your question regarding the VICON and
MAC systems? It's always of interest to get these insights.
Thanks,
Mark Redfern

>From N. Alberto Borghese dr. Eng.
I would not recommend neither of them. I have experience with Elite system
and I like it vvery much both in terms of accuracy result in standard routinary
use in the lab and easiness of use. Its algorithms are among the most advance
in the field and a recent benchmarkamong Elite, Motion and VIcon performed in
Jpan gave to Elite the credit to be the best instrument both in accuracy and
processing time.

>From Michael Whittle, MD, PhD
Dear Dr. Jenp:
Like you, I had to make the difficult decision as to whether to go with Vicon
or Motion Analysis, when planning a lab a couple of years ago. For a long
time I was planning on getting a MAC system. Then Vicon relased their clinical
software package, and I changed my mind. I don't think the differences between
the two systems on the "front end" are big enough to matter, but the ease of
producing clinically useful data certainly makes me happy with my decision to
go with Vicon. I haven't seen the new system yet, but I gather it still uses
the same clinical software, so these comments should still apply.

Best Wishes!

Yue-Nan Jenp, M.D.