sorry about the delay in posting -- the leftovers didn't come back to
me, so i couldn't bring them to 303, which is also my reminder to
post, so i forgot to post.


Computer Graphics                                                    Homework 7
CS417/CS418 Fall 1998                                Due WEDNESDAY, May 5, 1999

+ Hand in each question SEPARATELY.  There is NO CS418 part.

+ Make sure your names are LEGIBLE and EASILY SPOTTED
  at the TOP on the FRONT page of each question.  
  (Highlighting/circling helps)

+ You will be graded on correctness and also clarity and conciseness. 

+ E-mail how many total hours PER PERSON you spent on this homework
  by midnight, Sunday, May 9.  Feedback is also appreciated.

################################# CS417 part ##################################

1. Let p1, p2, p3 be distinct points in 3D; they define a plane.
   Compute the projection q of a point p onto the plane,
   i.e. compute the point q on the plane that is closest to p.

   Your answer should be an explicit formula.

   HINT: it involves the normal.

2. (Radiosity)

   Suppose initially there were no patches A_1, A_2.
   Suppose we break up patch A_3 into A_1, A_2 (so A_3 disappears).

   Relate new areas A_1, A_2 to old area A_3.
   
   Relate new E_1, E_2 to old E_3.

   Let j>3 be arbitrary.  Relate new form factors F_j1, F_j2 to old F_j3.

3. Give an example where both forward and inverse mapping could be used,
   but where inverse mapping is better.

   List 2 examples where linear interpolation is used besides Phong
   and Gouraud shading.

   List 2 uses of normals besides in calculations of specular and
   diffuse components.
-- 
Thomas Yan <tyan@cs.cornell.edu>           I don't speak for Cornell.
Computer Science Department \\ Cornell University \\ Ithaca, NY 14853
(please pardon any lack of capitalization -- my hands hurt from typing)