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Math 149, Spring 2001

The Mathematics of Computer Graphics

• Official Information
• Description
• Virtual Office Hours
• Handouts
• Lecture Notes
• Linear Tranformation demo in Java
• Splines, Lagrange, etc.

Daily notes

• 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.