Bezier

Bezier

Post by 11BD.. » Fri, 09 Mar 1990 05:03:00



  Will you please send me an algortihm of Bezier?

Thank-you,
Beverly Dodd



P.O. Box 489, 800 Florida Ave., N.E., Washington, DC 20002
"Gallaudet University is the only university for the deaf in the world."

 
 
 

Bezier

Post by d.. » Sun, 18 Mar 1990 08:36:17


READ THE MESSAGE BELOW CAREFULLY. See my comment below.


>   Will you please send me an algortihm of Bezier?

> Thank-you,
> Beverly Dodd



> P.O. Box 489, 800 Florida Ave., N.E., Washington, DC 20002
> "Gallaudet University is the only university for the deaf in the world."

Based on the number of messages of this type from this individual over the
last few months, it looks like she is asking the net to do her homework.
If this is in fact the case, then she is being dishonest. If it is not
then I expect to hear from her to the contrary. In that case I'll
apologize.

If students are given access to the net and then use it in the manner
suggested above, then the only recourse that a Professor has is to
restrict student access to the net. That would be a shame.

Those of us on the net should NOT participate in any activity of this
nature.

Professor David F. Rogers
Aerospace Engineering Department
U.S. Naval Academy
Annapolis, MD 21402
USA
Tel: 301-267-3283/4/5


UUCP:    ~uunet!usna!cad!dfr

 
 
 

Bezier

Post by Eugene Fiu » Sun, 18 Mar 1990 16:53:03



... A lot of stuff about student dishonesty, homework, expected apologies, etc.

The requests by this Dodd person have been so vague they're funny.  Given the
odd message routing through Berkeley, I prefer to think of them as hoaxes or
jokes.  As to the more general issue that Professor Rogers addresses (that of
people doing their homework based on submissions from the net), I suggest that
it's no more dishonest than those who consult a book to solve their graphics
homework.  Both may be dishonest practices, but they're equally so.  Curiously,
I haven't heard Professor Rogers or anyone else warning about the potential
abuses of graphics textbooks.
--
Eugene Fiume, Dynamic Graphics Project
Department of Computer Science, University of Toronto

 
 
 

Bezier

Post by mcoo.. » Mon, 19 Mar 1990 04:18:05


A bit general, don't you think?  Bezier curves? bezier patches?
2d? 3d? what?

 
 
 

Bezier

Post by Gregory L. Gallow » Mon, 19 Mar 1990 04:57:29




>> ... A lot of stuff about student dishonesty, homework, expected apologies,
>>     etc.

> ... A lot of stuff about hoaxes and jokes, abuses, etc.

I don't think this is a joke or a hoax. Clearly from the signature this is
a deaf individual from Gaulladet (sp?) University.  I replied once before to
this person and her friend to give them bibliographic information so that
they could better find their sources.  The root of their problem seems to
be their lack of a good technical library or book store.  They are unable to
get a hold of sources that a lot of take for granted.

I could be wrong, but this is how it appears to me. Even the messages read
like someone who is unable or has difficultly speaking, i.e. few or incorrect
verbs, etc.

On the subject of course work and texts abuses, I have never taken a computer
graphics course except for three at Siggraph.  I doubt that I will take any
more.  Computer graphics is a relatively young field. Most information about
it is found in books like those by Rogers and Siggraph proceedings. Now, I am
not a student and I bought Rogers' book.  If I were a student would I be
expected to reinvent such this a Bezier curves from scratch without a book.
If I am allowed to use a book but can't get access to one, what then?

This may come as a shock to most people but it appears to me that computer
science courses in computer graphics teach people existing (almost fundamental)
algorithms from a text like Rogers (it is used here at Tech) and expect that
students be able to implement them in code.  Most people never ever invent
a new or revolutionary algorithm, they just learn how the old ones work and
how to use and code them.  This seems to be life.  But from learning the old
ones and implementing them, a few go off and see a new way of doing things,
a way to speed things up.  They find a new algorithm.

I think it appropriate that if an individual cannot find a source of an
algorithm in their area, that they be allowed to publicly ask how to get it.
A valid response may be here's the address of the publisher and the ISBN
number, send them a check.

Lets help people get up to speed and avoid reinventing the wheel so that
the whole community can benefit from their efforts.  You may be cutting
off the next Bresenham.

We need LESS flaming in all net groups, especially computer graphics. Too many
times I have seen people get blasted from asking simple questions.  It cuts
down on the communication because it drives people away.

I'm also disappointed that comp.graphics does not discuss that many algorithms
for realistic three-dimensional computer graphics.  Most of the traffic is
taken up by requests for 2D PC stuff, and GIF-type images and converters.
Last time I posted a question about scan-line and A-buffer, only four people
responded: Loren Carpenter (the author), Charles Grant (former siggraph
tutorial teacher), Tony Apocada (pixar employee), and Charlie Gibson (from
rythym and hues).  Now this was a very impressive group of people, but where
were the responses from the countless anonymous people have implemented this
algorithms.  They have better things to do than read this group I guess, or
too busy Ray-tracing to care about any other algorithm.

Greg Galloway
Georgia Tech Research Institute
Georgia Institute of Technology
Atlanta, Georgia  30332-0280
(404)894-3357


--


GTRI/EML/EOD, Georgia Inst of Technology, Atlanta, Georgia  30332-0280

 
 
 

Bezier

Post by J. Michael Die » Mon, 19 Mar 1990 11:42:36


I think Gregory Gallaway made a good point: Computer Graphics is a rather new
topic and that few references are available on the topic.  I'm studying Math
and Computer Science here at UNM and am interested in graphics.

I read this news group simply because I want to know what people are doing in
this area of study.  I guess I COULD wait for the book.....in about 5 years!

I too, would like to see more discussion of algorithms.  I can program, so I
realy don't need to see code.  Pseudo-code would be nice though.  Discussion
of data structures would also be nice!

I really don't mean to flamme.....just putting in my 2 cents.

+-------------------------+----------------------------------------------------+
|  J. Michael Diehl  ;-]  |  I thought I was wrong once.  But, I was mistaken. |
|                         +----------------------------------------------------+



|  (303) 272-9845         |                                                    |
+-------------------------+----------------------------------------------------+

 
 
 

Bezier

Post by Steve Lamo » Mon, 19 Mar 1990 21:29:11



>Computer Graphics is no newer than any other portion of Computer Science.
>Indeed, it ties more closely with the main tradition in Math and Natural
>Philosophy than anything else in Computer Science except perhaps Numerical
>Analysis (which has sometimes been called: Computer Graphics Without Pictures).

I recall once hearing James Kajiya (smartest of all graphics smart-folk IMHO)
say that computer graphics is merely mathematical archeology.  

There may have been new mathematical techniques developed in graphics, but
I've yet to see one that is truly revolutionary.

                                                        spl (the p stands for
                                                        punting pixels in the
                                                        park)
--

NCSC, Box 12732, Research Triangle Park, NC 27709
"...though you may have the falcon yet we certainly have you."
                                Dashiell Hammett, _The Maltese Falcon_

 
 
 

Bezier

Post by Bob Webb » Mon, 19 Mar 1990 20:54:14



Quote:> I think Gregory Gallaway made a good point: Computer Graphics is a rather new
> topic and that few references are available on the topic.  I'm studying Math
> and Computer Science here at UNM and am interested in graphics.

Computer Graphics is no newer than any other portion of Computer Science.
Indeed, it ties more closely with the main tradition in Math and Natural
Philosophy than anything else in Computer Science except perhaps Numerical
Analysis (which has sometimes been called: Computer Graphics Without Pictures).

The literature is monstrous.  Really.  There are tons of books on all
manner of matters directly bearing on computer graphics.  Every
technical publisher has at least a dozen computer graphics books these
days (at least 2 or 3 new from each publisher each year) -- and then
there is the steady stream of conference proceedings, journals, and
dissertations -- not to mention the books/articles written by mathematicians,
engineers, and scientists, who have no interest in computer graphics but
are addressing issues that are central to it.

Quote:> I read this news group simply because I want to know what people are doing in
> this area of study.  I guess I COULD wait for the book.....in about 5 years!

Actually it is very rare for anyone to talk about unpublished work in
this group [ although it is not unusual for people to reinvent the
wheel in this group :-) ].  Indeed, a case could be made that it lags
at least 5 years behind the published literature (after all, it takes
a bit of time for enough people to digest a new concept that a
reasonable discussion on the matter can occur).  But, since there are
things published a 100 years ago that I am still trying to catch up
on, this is hardly a problem.


   The multitude of books is making us ignorant.  --- Voltaire.

 
 
 

Bezier

Post by Mark VandeWetteri » Mon, 19 Mar 1990 15:48:32


Concerning Ms. Dodd in particular, I urge people to ignore any of her
requests until she at least takes the time and effort to formalate a precise
question for the net.  Her questions are not even proper English, and show
that she has zero understanding of anything having to do with computer
graphics.

I would like to believe that it is some form of hoax, how bout someone fessing
up with a punchline?

As for people's gripes about using the net for homework, I mostly agree.
The way you learn things is to sweat things out a bit.  If you get totally
stuck, then go ahead and ask for references, pseudocode or even source,
but at least convince us that you have done some effort.

As for the lack of good references, there are now several "almost adequate"
texts out that should be useable.   For more research topics, hit the
Siggraph proceedings.  You can learn alot by just trying to implement
little bits and pieces.  Do a simple raytracer.  A scanline renderer.  A
ditherer.  You will learn a great deal.

Mark

 
 
 

Bezier

Post by Dave Martinda » Tue, 20 Mar 1990 00:02:38



Quote:

>.  As to the more general issue that Professor Rogers addresses (that of
>people doing their homework based on submissions from the net), I suggest that
>it's no more dishonest than those who consult a book to solve their graphics
>homework.  Both may be dishonest practices, but they're equally so.

Different courses have different standards of ethics.  In many courses
I've been in, it was considered OK (even expected) that you'd go look
at reference books to help understand an algorithm, but that you were
then actually supposed to implement it yourself - borrowing code from
other students was not considered OK.

I believe the reasoning was that you were supposed to do the assignment
not so that you could have a working assignment, but to demonstrate that
you knew how to implement a particular algorithm, or make use of a
particular set of library routines.  So any reference that helped to
understand the algorithm was OK, while any that helped you bypass
learning the algorithm was cheating.

In this sort of environment, asking USENET for help in understanding
an algorithm would be OK, while asking for code would not.  But this
is all relative to the "ethical standards" set out for the course,
which can be different for different courses and different professors.
Unless we know that, we can't judge whether a request is improper.
(It may be impolite or wasteful, but that's another issue).

(philosophical comment:)
It's so much more practical being a Researcher instead of a poor Student.
Researchers are allowed to use as much of other people's code as they
want, and to give their own code to other Researchers.  So much of
being a Student is demonstrating that you can reproduce yourself the
work that someone else has already done better.  I'm glad I'm not
a Student anymore.  (so why am I thinking of becoming one again
someday?)

 
 
 

1. intersection bezier/bezier &bezier/conic ?

hi there,

I am trying to solve the problem to intersect bezier curves and bezier curves
and algebraic curves, can somebody please point me towards information that can
help me to do that efficiently?

the solution I need, needs to be precise so polygonization of the curves
doesn't work. from reading books and scanning certain magazines, I think I
should be using an algorithm that utilizes implicitization of the parametric
curves.

thanks for any kind of input

ove

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