Past Midterm and Exam Questions (PDF) - Student.cs.uwaterloo.ca ...

52 CS488/688 Introduction to Computer Graphics
1. Primary rays
2. Shadow rays
3. Reflected rays
17.11 Distribution Ray Tracing [Last Used: Winter 2006 Final]
In distribution ray tracing, by casting many rays in a random fashion (i.e., “distributing them”)
we can simulate many effects. The “random fashion” part is what allows us to achieve our effects.
Describe what types of rays get “distributed” and what they “get distributed over” to achieve each
of the following effects. We have provided a model answer for “Anti-aliasing” to better indicate
what you should give for your answers.
Anti-aliasing — distribute primary rays over pixel area.
1. Soft shadows — distribute rays over
2. Motion blur — distribute rays over
3. Depth of field — distribute rays over
17.12 Ray tracing lighting [Last Used: Winter 2006 Final]
Consider a ray (P, ⃗v) that hits a surface S at a point Q, where the normal to S at Q is ˆn, and
where S has only diffuse reflection material components (d r , d g , d b ). Further, assume there is a
white point light at position L with RGB intensity values (I, I, I), and a white ambient light with
RGB intensity values (A, A, A).
In ray tracing, we want to know the intensity of light that travels back along this ray and
eventually reaches the eye. For the situation described above, explain how we compute this intensity,
noting any additional rays we cast and any local lighting computations we perform.
18 Splines
18.1 Bézier Curves: Evaluation and Properties [Last Used: Fall 2009 Final]
The following pictures show possible arrangements of control points for a cubic Bézier curve.
P
❜ 3
❜
P
❜ 2
❜ P 0
❜
P 1 ❜ P 2
P 0
❜
P 3 ❜ P 1