课程名称︰计算机图形
课程性质︰选修
课程教师：欧阳明
开课学院：电资学院
开课系所︰资工所、网媒所
考试日期（年月日）︰2008.05.07
考试时限（分钟）：
试题 :
Interactive Computer Graphics Midterm Exam May 7, 2008
1. (10%) Despite its weaker graphics capability than PS3 and XBox 360,
Nintendo Wii machine has gained more popularity than its competitors.
Please give your explanations on this fact. Why?
2. (20%) If one object bumps into another object, it is called
"Collision Detection". Why is it a basic and important component of
interactive computer graphics?
(a) (5%) Please give two examples or applications which use collision
detection algorithms.
(b) (5%) Given one object with N triangles in 3D space, and another with
M triangles, what is your simplest algorithm (brute force algorithm)
for collision detection? What is its complexity in computation?
(c) (10%) Can you think of a much better way for fast collision detection?
Please describe it and show its computatinal complexity.
3. (5%) What is your term project for this semester? What are the
technical difficulties involved in the project? (You can refer to
the project listing).
4. (15%)
Figure: http://i.imgur.com/Hlbg2eb.png
(a) Painter's algorithm draws polygons from back to front. Give an example
where painter's algorithm fails.
(b) BSP tree is an algorithm to address the problem painter's algorithm
faces. Construct the BSP tree for the following figure. Use face 1 as
the root.
(c) What is the display sequence if the eye is placed in the position
before face 3 and 2, but at the back of face 5.
5. (20%)
(a) (10%) Please describe the traditional graphics pipeline, and explain
what is done in each stage.
(b) (5%) Can you realize Phong shading by traditional graphics pipeline?
(c) (5%) What is GPU? Can it be used in Phong shading? Why?
6. (20%) Polygon rendering.
(a) (5%) What is the advantage of using polygons for rendering, instead of
using curved surfaces, or solid modeling (such as spheres and boxes).
(b) (5%) What is the advantage of using curved surfaces for rendering? How
to display it efficiently in practice?
(c) (10%) As shown in the following figure, in perspective projection the
silhouette (point B) of the polygon would be invisible. Discuss this
problem (how it happens and how to cure it), where N1 is the surface
normal at A, and N2 is the surface normal at B. E is the eye position.
Figure: http://i.imgur.com/g6YRT1m.png
7. (10%) There are nice properties about Ray Tracing. Please describe
the strength and weekness of Ray Tracing, using the theory of
"The Rendering Equation".