Home Page
Math 149, Spring
2001
The Mathematics of Computer Graphics
Daily notes
I'll put course announcements here rather than in Virtual Office Hours.
Please check here frequently, clicking on Reload to make sure you
see a current copy of this page.
- 6/13: In Handout QQ, the solution to Problem KK-3 is for the
wrong problem. The correct solution is now posted on-line in QQ.
- 6/12: Some errata: On the sample final, (c) should have been omitted
since we didn't cover basis functions for B-splines. Also, (k) doesn't
make sense as it is; the data should have been (0,0), (1,1), (2,8), and
(3,27). On Handout LL, solution to W-1, in several places x
should have been y . (Thanks to several of you for these.)
- 6/11: Brian is having extra office hours. From his web site:
EXTRA OFFICE HOURS: Tuesday, 6/12, 10-11am, and Wednesday, 6/13,
9-10:30am. Also remember that you can always send me e-mail!
- 6/9: In Handout RR (Solutions to sample final), Problem 3, the cross
product should be N = (-2,0,-2). In the on-line version of the handout
this has been corrected. The outward normal is OK. (Thanks to one of you
for pointing this out.)
- 6/9: Lab 3 grades have been recorded. I enjoyed seeing the
surfaces and animations you designed. On Lab 1 also, some people made
very interesting pictures--thanks. On all three labs I have made a note
of people who did an especially good job, which I can mention as part of
a recommendation in the future if you need one.
- 6/9: In connection with line segments AB, CD crossing,
some people have asked what happens if instead of having opposite signs,
one of the values f AB(C), f AB(D)
is 0, say the second of these is 0, so D is on the line segment
AB. Should we say the lines cross or not? I'd say that's
ambiguous. The choice of terminology would depend on the particular
application, and it often wouldn't matter. For example, if we are
trying to find whether the segment CD is partially hidden by a
face with edge segment AB, if only the point D is hidden
that won't affect how we draw the line.
- 6/9: In posting Friday's notes (10-F), I have fixed up p. 4 to be
clearer.
- 6/5: I will have an office hour Tuesday, June 12, 11:00-12:00, in
addition to the office hour Monday, June 11, 10:30-11:30.
- 6/3: For HH-5, you'll need to find the values of some basis
functions at t = 1/2 for splines with n = 2. You
can use Problem FF-4(d) for this.
- 5/25: You may delay handing in Assignment #9 until Friday, June 1.
- 5/25: Lab 1 scores should now be visible on My UCLA. They are 1 or 0
for pass/fail.
- 5/24: For Lab 2, please hand in your .cpp file by putting
it in your submit folder. Thanks.
- 5/24: As mentioned in class, the nominal due date is now effectively
Tuesday, May 29, but if you have special problems with getting it in
by then then just talk to me about it.
- 5/24: People are still having trouble opening the continents
file from within the program. The shortcut file seems to have the
same difficulty even if copied to your own folder. Instead, try
this:
Go to the handout file H:\class\m149.1\Lab2 with the NT
Explorer, right-click on the continents file (not the shortcut
to it), copy the file, go to your own working folder, right-click,
paste, right-click again, and rename the continents file
continents.dat. Then you can reference it in your program
just as continents.dat.
Or having done all this, if you have a program, say seeworld.exe ,
that reads the continents data from the standard input and writes the
"ez" file to the standard output, in the Command window you can give
the command seeworld.exe < continents.dat > earth.dat
(or whatever output file name you choose).
- 5/23: In Handout EE, p. 3, in opening the "continents" file there
are apparently two problems: First, the path should have "Lab2" in it,
and second, there may be a problem with the fact that the continents
file has no extension. I have made a shortcut so that you can use this:
ifstream fin("H:\class\m149.1\Lab2\continents.dat");
[This correction itself has been corrected to have m149.1 instead
of m149.] Could someone let me know if you're able to open
the file under this name? Thanks.
- 5/22: In Handout EE, where it says check visibility,
this part should be inside the preceding while loop, so that
it is done for each data point read in.
- 5/22: The program ez2gs.cmd has been updated and works for me.
Could someone else try it and let me know the result? Thanks.
- 5/21: Still some problem with ez2gs.cmd . I'm looking into it.
- 5/19: Try Lagrange and Bezier on the link "Splines, Lagrange, etc" above.
(These were programmed by a student a while back.) For Bezier, first click to make points.
- 5/19: I have put a couple of student questions with answers on VOH.
- 5/19: For Lab #2, I think we have the ez2gs.cmd file working now.
Find it in the folder H:\class\m149.1\Lab2 and copy it to your own
working folder, by dragging or by using copy/paste, or by making a shortcut.
You may also want to make a shortcut for the continents file and
drag that to your working folder. To plot your output: (1) Use your
program to generate your output file in "ez" format, say my_plot.txt or
whatever. (2) From the Start/Programs menu open a command prompt window.
(3) Get to your working folder by using cd with the folder path; you
can do this in stages. If you find you aren't on the right drive, first
give the drive letter with colon but without cd. (4) Use the command
ez2gs.cmd my_plot.txt (or whatever the file name is).
If this doesn't work, please let me know. Thanks.
- 5/16: In Handout W, the terminology "blending function" is used
instead of "basis function"; these are the same thing.
- 5/16: Errata: Handout W, p. 5, near the bottom, p 2
should be positive, not negative, and the resulting signs should be changed
from - to + in the formula for P(t) . Problem W-10: Technically,
the problem should say n > 0 , since a constant polynomial could
touch a circle in one point, which is more than 2n if n=0.
(Thanks to DK and GC.)
- 5/15: For handouts, I had been providing several versions, but it
turns out that when the .html version of math-oriented handouts is given,
the software does not produce the .ps version. Does anyone have a problem
if I include the .ps version and omit .html? The .pdf version is best anyway.
(This does not apply to handouts with no math symbols, such as homework
assignments; for these .html will be provided.)
- 5/13: For Lab 2, the ez2gs.cmd software has not yet been put on line.
- 5/13: Midterm grades have been posted on My UCLA. Solutions will be
provided in class and on the web.
- 5/10: Some misprints were noted and have been posted on VOH. Thanks
especially to D.K.
- 5/10: When viewing this page and also VOH, click "reload" or the
equivalent on your browser to make sure you're seeing the most recent
version; you could be viewing an older cached version instead. (Sorry
if you don't see this reminder for that very reason!)
- 5/10: Some people were bothered by their answer to S-12. But S really
is above the plane of the triangle PQR, so that when viewed from
above, PQR is hidden by the rest of the tetrahedron.
- 5/10: Although the sample midterm doesn't ask for oblique
subclassifications, you are still supposed to know them.
- 5/7: In today's lecture (6-M), the explanation of how the visibility
example was invented needed fixing. The on-line version has been corrected
(p. 4). This was an optional comment anyway.
- 5/7: One of you asks for a clarification of Problem S-6(a).
The idea is that, while homogeneous linear transformations always
preserve linear combinations, translations usually don't--but they
do preserve barycentric linear combinations.
Recall that a transformation T is said to "preserve
a linear combination" when T(c 1 P 1 +
... + c k P k ) = c 1 T(P
1 ) + ... + c k T(P k ). So you
are supposed to show this is true when T is a translation and
the linear combination is barycentric.
- 5/6: Midterm announcement: For the midterm Friday, we now have
a larger room where you can spread out: Rolfe 1200.
- 5/3: Erratum: In Assignment #6, omit P-11, which was assigned previously.
- 5/3: In submitting the lab, people are getting an error saying
that a .pm file is missing (if I understood correctly). I'm not sure
about the cause, which has something to do with the submission software,
but don't worry about it, since I am able to access the files without
a problem.
- 5/2: Glasses case found in classroom. I'll bring it to class
Friday, or you can get in touch with me sooner.
- 5/1: For Lab 1, I had not fully understood the Windows NT setup,
so I have modified it only today. If you have already submitted files
one way or another, I can cope, but it has now been set to expect
files named lab1A.ps and lab1B.ps .
- 4/30: For info on Postscript, see
Postscript Tutorial . (Thanks to Tony for this reference.)
- 4/30: In Assignment #5 you may omit Problem P-10, which depends
on the "rotate the earth" method that we have not yet finished
discussing in lecture.
- 4/30: See
Arcade Data .
- 4/18: As handed out, Assignment #4 (Handout K) had an error: It
was labeled Assignment #3. This has been corrected in the on-line version.
- 4/16: For lectures through Wednesday of the second week, I have
posted some transparencies from an earlier offering of Math 149.
They are very similar to what we did in class, but material covered
on one day in our class may have been discussed on a different day in
the previous class.
- 4/13: Starting today, I'll be scanning in transparencies from
lectures.
- 4/4: Erratum: On Handout E, p. 1, Example, A should be m by n.
- 3/29: On Friday, April 6, we'll have a demo of the Visualization
Portal in MS 5628. Because the class is large, there will be two
sessions: 11-12 (the regular class time) and 12-1 (the hour after).
Monday and Wednesday in class we'll have signups. Come on time to
your session!
- 3/29:
Permission to enroll is necessary. The class is full; no new
PTE's will be given out, except that people to whom I promised
admission but who do not yet have a PTE number should see me.