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AIList Digest Volume 5 Issue 091
AIList Digest Monday, 30 Mar 1987 Volume 5 : Issue 91
Today's Topics:
AI Tools - TMYCIN: Free EMYCIN-like ES Tool,
CAD - Solid Modeling & CAD/CAM/Robotics/Vision Policy,
Comments - American Militarism & Ad Hominem Arguments
----------------------------------------------------------------------
Date: Fri 27 Mar 87 17:39:04-CST
From: Gordon Novak Jr. <AI.NOVAK@R20.UTEXAS.EDU>
Subject: TMYCIN: Free EMYCIN-like ES Tool
The following two messages contain the code and documentation for a
small EMYCIN-like expert system tool called TMYCIN (for Tiny EMYCIN).
TMYCIN is written in Common Lisp (in a rather "old" Lisp style to make
it easy to port to other dialects). Since it is only about 10 pages
of code, it does not implement all of the features of EMYCIN, but it
does cover some of the most-used features. The implementation is a
new one, written from scratch, so it is different internally from EMYCIN;
however, I have tried to follow EMYCIN conventions where possible.
TMYCIN was originally written for use in an AI and Expert Systems course
taught at Hewlett Packard. While it is not an "industrial strength" ES
tool, others may find it useful for teaching or for self-study.
The Artificial Intelligence Laboratory at the University of Texas at Austin
receives major support from the U.S. Army Research Office under contract
DAAG29-84-K-0060. The A.I. Lab has also benefitted from major equipment
grants from Hewlett Packard and Xerox.
Enjoy...
Gordon Novak
[Remember the AI Expert sources? I had to set a policy
of not distributing large amounts of code. Granted, the
two digests worth of code and examples is much smaller, but
the same principle seems to apply. I would also prefer not
to be responsible for such distributions because people ask
for the code with fair regularity; I then have to keep it
on disk or repeatedly pull it from tape, and my company has
to bear the cost. I'm open to suggestions for how code should
be handled, but AIList doesn't seem to be the place. (Usenet
has a comp.sources, and there is a Unix code distribution,
but Arpanet really has no mechanism other than contacting the
author or FTPing his files.) -- KIL]
------------------------------
Date: 27 Mar 87 20:12:10 GMT
From: ssc-vax!thornton@BEAVER.CS.WASHINGTON.EDU (Ken Thornton)
Subject: Solid Modeling
Unfortunately, there is no CAD/CAM, Robotics, or Automation newsgroups
so I decided to post here.
I am interested in hearing from people who know about solid modeling systems
and have experience using them. Specific questions I'm interested in are:
What is generally preferred, constructive solid geometry (CSG) representations
or boundary represesentations (B-rep)?
Of the available commercial systems, is CSG or B-rep more predominant?
I am specifically interested in generating procedures for a robotic vision
system to automatically inspect a part, given a solid model of the part.
In addition to the actual part model, it would be necessary to have
information about specific features, relationships between features,
feature tolerances, and object surface reflectance. From what I understand,
commercial systems do not provide this information in the output file
representation of the part.
More than anything, I'm interested in stimulating some discussion about
solid modeling and related computer graphics algorithms. If such a
discussion is considered inappropriate to this newsgroup, I might be interested
in forming another group or starting a mailing list, if anyone is
interested.
Ken
--
Ken Thornton {decvax,ihnp4}!uw-beaver!ssc-vax!ssc-bee!thornton
Boeing Aerospace PO Box 3999 MS 2E-73 Seattle, WA 98124-2499
"A little learning is a dang'rous thing" - Alexander Pope
------------------------------
Date: 29 Mar 87 04:14:36 GMT
From: rpics!chassin@seismo.css.gov (Dave Chassin)
Subject: Re: Solid Modeling
In article <798@ssc-bee.ssc-vax.UUCP>, thornton@ssc-vax.UUCP
(Ken Thornton) writes:
>
>
> Unfortunately, there is no CAD/CAM, Robotics, or Automation newsgroups
> so I decided to post here.
I guess it as good a place as any...
>
> I am interested in hearing from people who know about solid modeling systems
> and have experience using them. Specific questions I'm interested in are:
>
> What is generally preferred, constructive solid geometry (CSG)
> representations
> or boundary represesentations (B-rep)?
>
> Of the available commercial systems, is CSG or B-rep more predominant?
Preference really depends on application (see below), as for predominance, it
depends on what system you using. B-rep modeling is the predominant form
of geometric data representation on microcomputers. This is mainly because
of memory/speed restrictions that have existed since the dawn of micros
(things are changing but not yet enough, and not fast enough). CSG is
far more common on minis and mainframes for the same reasons, but also
because data is much more easily manipulated, and more logically in terms
of geometric thinking (unions, intersections, cutting, etc). My preference
(as an architect) is to use CSG for conceptual manipulations, and B-rep
for detailed representations. Each have their limitations, and if anyone
is interested, we can discuss these at great length sometime later.
>
> I am specifically interested in generating procedures for a robotic vision
> system to automatically inspect a part, given a solid model of the part.
> In addition to the actual part model, it would be necessary to have
> information about specific features, relationships between features,
> feature tolerances, and object surface reflectance. From what I understand,
> commercial systems do not provide this information in the output file
> representation of the part.
CSG seems to me to be the most readily applied to this type of work. The
reason is that CSG can naturally indicate whether two parts geometrically
intersect each other, for example. However surface features like color
and reflectances are not inherently applied to CSG modeling, although I imagine
this could be developed, and might even be worth while. B-rep seems to be
a bit more of a problem in terms of manipulating relationships between parts.
I think that you have another problem when you get involved with robotic
vision,
and this is something that I've never thought about in terms of robotics, but
I am working on in terms of architectonics (architectural modeling of sorts).
That is that you will need to create some sort of algorithm for generating a
3D model from 2D information received by the cameras. Essentially the idea
is to analyse a pair of images, extract the boundary data, assemble a 2D
'image' for each view, project the two images together into a 3D 'image',
and finally take the resulting B-rep data and convert it to CSG type data,
which can then be correlated with the previous frame and the motor algorithms
to properly direct the parts into their desired positions. Piece of cake, eh...
Each of these steps involve some very complicated and SLOW computing. I've
worked out the basics for the first 4 steps, but have a long way to go
still. In any case I would love to talk more about the ins and outs of this
type of analysis because this is the main focus of my work for the next
year or so. By the way, it's all being done on a Sun 2/120 and 2 AT clones...
...wish me luck!!!
I know there are some people who have already done some work in these areas,
but it has always amazed me how little is in fact published. I have NO, get
that, NO references relating to 3D reconstructions other than the following,
and these have nothing to do with computer application thereof:
Wittcower & Carter, "The perspective of Piero della Francesca's
Flagellation", COURTAULD INSTITUTES, vol.16, 1953
In this article the authors explain the method they used for reconstruct
the actual architectural space that Piero painted. The mathematics of
perspective are treated, and discussed.
Since this is obviously not directly related to the subject I would
greatly appreciate any sources anyone might know of. They are rare, and
those that I have found, uninspiring.
So, anyway, I encourage further discussion of this topic as it is a very
difficult one, and it will, I believe, in the long run test what we
computer graphics buffs are really made of. This problem goes beyond
simply one of analysis, to become one of representation and ordering. The
results, or lack thereof, will reveal much more about how we perceive and
order what we see. This is the heart of the problem.
_____________________
David P. Chassin
Rensselaer Polytechnic Institute |
School of Architecture __+__
Troy, NY 12181 / _ \
USA | | | |
/=======/ = \=======\
(518) 266-6461 | _ | _ | _ |
| | | | | | | | | |
chassin@csv.rpi.edu | = | | | | = |
=======================================================================
The above is my opinion, and mine alone. The organization I belong to
may refute these statements at any time. They are however more likely
to take credit for them.
=======================================================================
------------------------------
Date: Sun 29 Mar 87 21:55:16-PST
From: Ken Laws <Laws@SRI-STRIPE.ARPA>
Reply-to: AIList-Request@SRI-AI.ARPA
Subject: Policy - CAD/CAM/Robotics/Vision
I hate to turn away AI-related discussions, but CAD/CAM,
Robotics, and Vision are large enough areas that they
should have their own lists. I've heard that there is
a CADinterest^.es@Xerox.COM list (reachable via seismo
from csnet) that discusses VLSI design, CAD workstations,
etc. There are Arpanet lists for graphics
and for workstations, as well as Vision-List@ADS for
machine-vision discussions. I don't know of any robotics
list, although Vision-List has carried related messages.
(Vision workers are often interested in path planning and
other robotic issues.)
Some of the aforementioned lists have been inactive lately.
You could either "take over" one of their discussions for
awhile or start a new list that combines your own interests.
I'm told that an AI-Hardware list will be formed soon --
perhaps CAD/CAM will be of interest there.
-- Ken Laws
BTW, there is indeed a literature on combining 2-D views to
construct 3-D objects -- both for converting mechanical drawings
to solid models and for extracting buildings from aerial
imagery. I don't have references handy, but Tom Strat
here at SRI published some papers on this a year or so ago.
Underwood also worked on this problem, as have others. There
is also a vast literature on combining stereo views to obtain
3-D models for robotic inspection and grasping.
------------------------------
Date: Sat 28 Mar 87 11:58:49-EST
From: Richard A. Cowan <COWAN@XX.LCS.MIT.EDU>
Subject: Re: American Militarism
(This is a condensed version of a response I sent to Tetsuo Tomiyami:)
Although I may share your sentiments regarding the military emphasis
of computer science, I agree with Ken Laws that the the mention of
military applications in AILIST is appropriate and should not be
censored out, for two reasons.
First, if there is military research going on in AI on the automated
battlefield, I think it is better that this be acknowledged openly
than hidden from view. Keeping military work shielded from view
merely makes this work more difficult to criticize. Acknowledging
its presence allows affected communities (such as the AI community) to
openly debate the nature of such work and reach a community decision.
Second, I don't think your analogy (to showing pornography in public)
holds. The harmful effects of showing pornography (not erotica, but
degrading, sexually exploitative material) come directly from showing
it, but the harmful effects of military work do not come from merely
acknowledging its presence.
I think it would be more constructive to engage people on the AILIST
in discussions of the implications of military AI. If people
responded by saying that discussion about the effects of AI research
on society are irrelevant to the list because they are political
questions, *then* you might have something to gripe about. Why?
Because scientists and engineers (especially those who receive public
funds) have a responsibility to society to consider the implications
of their work. Therefore, discussion of the implications of military
AI (or civilian AI) is totally appropriate, and should not be
suppressed in one of the major forums for communication used by AI
scientists. (Though it is certainly appropriate for a moderator to
cut out stuff to prevent flaming from getting out of control.)
Now that Artificial Intelligence, having found uses in society, is no
longer an ivory tower avocation, politics is not extraneous to AI.
Rather, as the AAAI conference on "Issues Concerning AI Applications
To Battle Management" shows, AI *is* political.
-rich
------------------------------
Date: Sat, 28 Mar 87 13:52:49 EST
From: cross@nrl-css.arpa (Chuck Cross)
Subject: ad hominem arguments
Phil Marks' reply to Tetsuo Tomiyama begins: ``Very interesting...that we
should get such an opinion from a Japanese'' [the dots are his]. I can
think of nothing more offensive in a discussion than using a person's race
or national origin to ridicule his position. It is the worst kind of ad
hominem argumentation.
Chuck Cross
------------------------------
End of AIList Digest
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