Computer Science 455

Instructor: R. P. Burton

Fourth Quiz

March 6-7, 2006

Name _________________________________________ Score ____________/41

1. In order to do computer graphics, at least one input device besides a keyboard is needed.

   1. true

   2. false

(b)

2. Suppose you have a tablet with 1024 embedded vertical wires, and 1024 embedded horizontal wires. Each wire has a signal which can be “heard” by a stylus. What is the minimum number of bits needed for the signal in any particular wire?

   1. 1

   2. 10

   3. 11

   4. 20

(a)

3. The sensing mechanism(s) used by touch panels is/are

   1. optical

   2. electrical

   3. acoustical

   4. some, but not all of the above

   5. all of the above

(e)

4. The “light pen” is so named because

   1. it is relative light weight

   2. it produces light

   3. in senses light

(c)

5. The Lincoln Wand used _____ microphone(s) to sense the 3D position of an input device.

   1. just one

   2. two

   3. three

   4. four (or more)

(d)

6. How many strip microphones are needed to detect a position on a 2D surface?

   1. one

   2. two

   3. three

   4. four

(b)

7. How many point microphones are needed to detect a position on a 2D surface?

   1. one

   2. two

   3. three

   4. four

(b)

8. The ultimate (i.e. the one which makes input the easiest) graphics input system is a voice-driven input system.

   1. true

   2. false

(b)

9. Any of the logical input devices discussed in class can be modeled by any of the physical input devices discussed in class.

   1. true

   2. false

(a)

10. Where would you place normalized device coordinates?

    1. before modeling coordinates

    2. between modeling coordinates and world coordinates

    3. between world coordinates and screen coordinates

    4. after screen coordinates

(c)

11. What is the purpose of graphics standards?

    1. to protect against garbage software

    2. portability

    3. to accommodate tradition

    4. to accommodate the Germans

(b)

12. Which of the following is least desirable?

    1. painted and posted

    2. painted and not posted

    3. not painted but posted

    4. neither painted nor posted

(b)

13. If a graphical entity is not always transformed as a unit, it should be subdivided into simpler objects/segments.

    1. true

    2. false

(a)

14. A model consists of

    1. data

    2. a combination of data and procedures

    3. procedures

    4. any of the above

(d)

15. Changing an individual element of a scene typically is easier with a _____ transformation hierarchy.

    1. flat

    2. tall

(a)

16. Fewer fundamental classes/symbols need to be defined in a _____ transformation hierarchy.

    1. flat

    2. tall

(b)

17. Suppose 12 matrices needed to be concatenated to produce a transformation for a chair (in a tall hierarchy). How many matrices need to be concatenated to produce a transformation for a desk in the same office as the chair?

    1. 12

    2. more than 12

    3. 11

    4. 2

    5. none

(d)

18. Suppose several objects are defined relative to the origin of master coordinates. How can clipping of a single object take place in master coordinates?

    1. it can’t unless the multiple objects are geometrically disjoint in master coordinates

    2. by translating the object to be clipped beyond the geometric extent of the other objects

    3. without doing either (a) or (b)

(c)

19. Placing a cursor within the geometric boundaries of an object is sufficient to “pick” that object.

    1. true

    2. false

(b)

20. What is the maximum number of devices that can be in request mode at any one time?

    1. one

    2. two

    3. unlimited

(a)

21. What is the maximum number of devices that can be in event mode at any one time?

    1. one

    2. two

    3. unlimited

(c)

22. The event queue should allow

    1. only one event from each device and that should be the oldest event

    2. only one event from each device and that should be the newest event

    3. multiple events from any device until the event queue is full, and those should be the oldest events

    4. multiple events from any device until the event queue is full, and those should be the newest events

    5. (can’t say in general)

(e)

23. Which of the following would be LEAST desirable (in terms of efficiency) or is impossible for drawing/erasing rubber lines?

    1. draw and erase using XOR

    2. capture the pixels where the line is to be drawn, draw the line, and subsequently restore the contents

    3. re-render the entire scene whenever the line moves

    4. allocate a high-priority bit plane for the line

(c)

24. The concepts and techniques needed for “stroke” (as opposed to raster) character recognition contemplate _____ of class presentation.

    1. perhaps an hour

    2. two weeks (i.e. 6 hours)

    3. a full semester

(a)

25. ________ activities typically are more demanding conceptually that _____ activities.

    1. Analytic, synthetic

    2. Synthetic, analytic

(b)

26. What is the greatest dimensionality of a point which can be presented, unambiguously, using parallel axes coordinates?

    1. two

    2. three

    3. four

    4. significantly more than four

(d)

27. Suppose a cube is represented in wireframe form, with all edges visible. The ______ edges should be “thicker/bolder” to emphasize their relative position.

    1. near

    2. farther

    3. (can’t say in general, since different people will interpret “thickness/boldness” differently.)

(c)

28. Where is the “center of projection” for a front elevation blueprint for a home?

    1. in the same plane as the front wall

    2. at the property boundary

    3. far, far away (well beyond Judea’s plains – actually they are hills)

(c)

29. If points are projected to the view plane along lines that are parallel, that is synonymous with lines that are projected perpendicular to the view plane.

    1. true

    2. false

(b)

30. Parallel orthographic projection can be as simple as “drop z” (unrelated to edema).

    1. true

    2. false

(a)

31. Perspective projection can be as simple as “division by depth.”

    1. true

    2. false

(a)

32. Blueprints for homes typically are parallel projections because, historically, it took too much work to produce perspective projections. As computer graphics has become part of residential architectural design, blueprints are moving toward perspective projections.

    1. true

    2. false

(b)

33. Oblique projections are more likely to be useful for ________ projections.

    1. parallel

    2. perspective

    3. neither parallel nor perspective

(a)

34. An arbitrary polyhedron approximated by polygons can have (at most) ______ vanishing point(s).

    1. one

    2. two

    3. three

    4. lots more than three

(d)

35. The viewing transformation involves, quite simply, the mapping of one coordinate system onto another.

    1. true

    2. false

(a)

36. Which of the following is NOT an advantage of near and far planes?

    1. selecting only a volume of space beyond the near plane and in front of the far plane

    2. taking cross sections

    3. increasing the precision of calculations

    4. (no exceptions here)

(d)

37. All view volumes can be converted to a regular parallelepiped except a view volume resulting from a _____ projection.

    1. parallel oblique

    2. perspective orthographic

    3. perspective oblique

    4. (no exceptions here)

(d)

38. A curve cannot intersect itself. Otherwise there are multiple values of one variable for one value of another variable.

    1. true

    2. false

(b)

39. Which of the following communicates that two curve sections do not meet?

    1. zero-order continuity

    2. first-order continuity

    3. second-order continuity

    4. (none of the above)

(d)

40. All things considered, the advantages of curves which _______ control points generally outweigh the advantages of curves which _______ control points.

    1. approximate, interpolate

    2. interpolate, approximate

(a)

41. The Bezier coordinate function is

    1. composed of parts and pieces which have intuitive meaning for the typical CS 455 student

    2. beyond the grasp of the typical CS 455 student; he should be content that the derivation presented in class is correct

(a)