Midterm Study Guide Corrections

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• Better solution to problem 2.b.2:
  TRUE -- the lengths of lines do not vary with distance from the viewer, and lines that are parallel in world coordinates will remain parallel after projection.
  
  
• Correction to solution to problem 2.b.4:
  TRUE -- Parallel projection is an affine transformation that does *not* preserve angles after projection.
  
  
• Clarification in problem 3:
  The viewer is assumed to be looking down the +z axis for this problem, so larger z is further away. To think of this problem in terms of the lecture notes, where the viewer is looking down the -z axis, you need to reverse the comparisons (swap "<" and ">").
  
  
• Correction to solution to problem 4:
  i. The storage is in the worst case N^2 not 2^N.
  
• Problem 1a:
  
  MFR = T(1,0) * R(theta) * T(0,-3/2)
  
  i.e., the leftmost translation needs to be changed. Likewise in problem 1b.
  [One of the previous incarnations of this problem actually carried a scale transformation down the hierarchy. To clean it up, we moved the scale into the definition of the object. Unfortunately, a scale-dependent answer was still left in the solution. My apologies for not detecting this earlier.]