課程名稱︰虛擬實境
課程性質︰選修
課程教師：歐陽明
開課學院：電資學院
開課系所︰資工所、網媒所
考試日期（年月日）︰2014.05.11
考試時限（分鐘）：
試題 :
Virtual Reality Midterm Exam(Make-up) May 11, 2014
1. (15%) da Vinci Surgical System
The da Vinci System is designed to facilitate complex surgery using a
minimally invasive approach. It consists of a surgeon's console that is
typically in the same room as the patient, and a patient-side cart with
four interactive robotic arms controlled from the console. Please answer
the following questions:
http://i.imgur.com/4Zp38no.png
(a.) (10%) What technologies related to Virtual Reality are involved in
this system? Please list 3 items and give a brief explanation.
(b.) (5%) How can the surgeon know that the robotic arms had touched the
patient? What good things will you design to inform the surgeon about
the above situation?
2. Term project (5%)
What is the term project you want to do for this semester? What kind of
technical problems will you encounter and have to be solved?
3. (25%) In terms of graphics acceleration, there are at least two approaches
been proposed, namely (1) parallel processing or SIMD, such as in the
nVidia GeForce chip set, and (2) binary machines such as the PixelPlanes
chip set.
(a) (10%) There is a functon fast_calculate (A, B, C, x, y) which can be
evaluated in parallel, where fast_calculate() can calculate
Ax + By + C for each pixel position (x, y) in PixelPlanes. For a
triangle defined by vertices (1, 2), (4, 4) and (7, 0), please write
a parallel procedure using fast_calculate() to draw all the pixels
inside this triangle.
(b) (10%) For the triangle defined by vertices (1, 2), (4, 4) and (7, 0)
with their colors on blue channel are 17, 31, 21, respectively. Please
provide the precise A, B, C values such that the result of the formula
Ax + By + C indicates the value of the pixel(x, y) on the blue channel
using Gouraud shading (smooth shading, or called color interpolation
shading).
(c) (5%) Please calculate the color values of the pixels (4, 3) and (5, 2)
by adopting your formula in (b).
4. (10%) Motion Capture
Motion capture is the process of recording the movement of objects or
people. Traditionally, the captured subject would wear several markers
and the related motion would be recorded by several surrounding cameras.
Nowadays, Kinect uses depth cameras to track human skeleton motion.
Hint: Kinect's depth acquisition is enabled by "light coding" technology.
The process codes the scene with near-IR light, light that returns distorted
pattern depending upon where things are. The solution then uses a standard
off-the-shelf CMOS image sensor to read the coded light back from the scene
using various algorithms to triangulate and extract the 3D data.
(a) (5%) Compare the traditional maker method and Kinect system. What are
the pros and cons of each method?
(b) (5%) Assume that you can capture human skeleton motion successfully.
Please give one example of the possible cool usage, especially those
that are not yet mentioned in the Internet introduction.
5. (20%)Tracking problem. From one camera, you are looking at a triangle with
known vertex positions, such as A(1, 3, 10), B(8, 30, 10), C(20, 2, 10).
(a) (10%) How to determine the distance and orientation of the camera to the
triangle?
(b) (10%) In actual use, there are cases when one vertex of the triangle is
blocked from the camera's view. What would be possible solutions to this
problem? Please state your solution clearly and with explanation.
6. (10%) In Windows 8, a multi-touch screen similar to Apple's I-phone is one
unique way to provide new user interfaces.
Assume that we have "two" cameras in each Notebook PC, located at the top
right and left corner of the screen.
(a) (5%) Can you describe a way to provide "multi-touch" user interfaces
without even "touching" the screen?
(b) (5%) Please describe your algorithm to solve the problem of determining
finger positions (not just one, but perhaps two fingers).
7. (10%) 3D sound:
The goal of 3D sound is to simulate the direction and distance of a sound
source in a real world
(a) The DVD standard uses the Dolby AC-3 as its sound output, where AC-3
uses 5 speakers plus one bass speaker, as shown in Figure (a). However,
your PC has two speakers only. How would you design your PC to play a
DVD movie with a sound similar to Dolby AC-3?
http://i.imgur.com/Wkq559L.png
8. Force-feedback devices (15%)
Allen builds his 3D sculpting system with a force-feedback device. The
pseudo code of his main algorithm is given in the following:
┌────────────────────────────────────┐
│while(sculpting){ │
│ Do the "collision detection" with current sculptor position │
│ Calculate the "feedback force" and send it to force-feedback device │
│ Modify the 3D scene │
│ Render the 3D scene │
│} │
└────────────────────────────────────┘
Assuming the joystick stiffness = 0, mass = 0.5 KG, and
viscosity = 4 NT-Sec/Meter, While human operator (arm and wrist)
stiffness = 400 NT/m, viscosity = 3 NT-Sec/Meter, and mass = 3 kg.
(a) (5%) Let's simulate a spring (with spring constant K = 100) with a
length of 50 cm, while at both ends are "rock" walls (hard surface)
using such a spring system using a large spring constant
K = 1000000 NT/m. Your joystick is at the middle of the spring, say at
25 cm. Please write down your simulation equations.
(b) (5%) Do you think it is a good system design? What are the potential
problems?
Hint: (for a system to be stable: Sampling period T <= B/K, where B is
the total system viscosity, K is the total system stiffness.)
(c) (5%) For the problem in (b), can you think of ways to actually simulate
a hard surface in virtual reality, and still feels "realistically"?
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