Computer Science 455
Instructor: R. P. Burton
Second Quiz
May 10-11, 2004
Name _________________________________________ Score ____________/46
1. Computer graphics is appropriate for producing
a. only cartoon-like images
b. only painterly images
c. photorealistic images
d. cartoon-like images, painterly images, and photorealistic images
(d)
2. Image processing and computer graphics are
a. synonyms
b. one is a subset of the other
c. opposite ends of a spectrum
(c)
3. Graphical User Interfaces (GUIs) are
a. an application which uses traditional graphics capabilities
b. a research area where progress depends primarily on the development of computer graphics techniques
c. the pinnacle of computer graphics
(a)
4. What is the purpose of the cathode in a CRT?
a. to produce electrons
b. to fire electrons toward the screen
c. to maintain the image on the screen
(a)
5. Why should the image on the screen be refreshed approximately 30 times/second (or more)?
a. to accommodate the termination of phosphorescence
b. to accommodate the human visual sampling rate
c. to be compatible with the TV industry
(b)
6. High-persistence phosphors typically are not used because
a. they are very costly
b. they are not sufficiently durable
c. they are suitable only for static images
d. they produce “color bleed”
(c)
7. Which of the following occurs first?
a. fluorescence
b. phosphorescence
c. refresh
(a)
8. If the display is 480 x 525 with 1 byte for each of red, green, and blue, the frame buffer should be approximately _____ kilobytes
a. 25
b. 75
c. 250
d. 750
e. 2,500
f. 7,500
(d)
9. The “jaggies” are associated with
a. vector displays
b. calligraphic displays
c. raster displays
d. (all of the above)
(c)
10. The technology associated with most television sets in American homes is
a. beam penetration
b. vector
c. shadow mask
d. plasma
(c)
11. A shadow mask CRT has e electron gun(s), d deflection system(s), and f focusing system(s). e + d + f =
a. 3
b. 4
c. 5
d. 6
e. 9
(c)
12. A direct view storage tube has e electron gun(s), d deflection system(s), and f focusing system(s). e + d + f =
a. 3
b. 4
c. 5
d. 6
e. 9
(b)
13. Which of the following is NOT an advantage of the plasma panel?
a. selective writing and selective erasure
b. no need to refresh the image; “sustaining” the entire display will do
c. high resolution
d. flat and robust
e. (all are advantages)
(c)
14. Which of the following produces true 3D output?
a. varifocal mirrors
b. bimodal projection
c. holograms
d. head-mounted displays
e. rotating LED panels
f. (none of the above produce true 3D output)
(f)
15. Scan conversion is the process of
a. traversing the screen in a raster fashion, essentially directing the beam at every pixel position
b. taking a signal produced by a computer and converting it to a signal anticipated by a TV monitor
c. digitizing a picture definition
(c)
16. Which technique is more likely to reduce the resolution of a presentation?
a. run-length encoding
b. cell encoding
c. (neither technique reduces the resolution of a presentation)
(b)
17. What are the “jaggies?”
a. the stairstep appearance attributable to a discrete pixel grid
b. irregular boundaries caused whenever a picture element totally lacks a red, green, or blue component in its color
c. tapering at the ends of lines on calligraphic systems as the beam is turned on or off during deflection
d. a British rock group named after a famous motorcar manufacturer
(a)
18. Suppose is line is to be drawn from (10,20) to (100, 200) using the DDA method. How many pixels are plotted (pick the correct range)?
a. 1 to 100
b. 101 to 200
c. 201 to 300
d. more than 300
(b – 180)
19. Continuing the previous question, how many pixels are plotted if the symmetric DDA method is used?
a. 1 to 100
b. 101 to 200
c. 201 to 300
d. more than 300
(c – 256)
20. Continuing the previous questions, how many pixels are plotted if the Bresenham method is used?
a. 1 to 100
b. 101 to 200
c. 201 to 300
d. more than 300
(b – 180)
21. What should be treated as the initial coordinates for plotting a DDA line between (10,20) and (100,200)?
a. 10, 20
b. 10.5, 20
c. 10, 20.5
d. 10.5, 20.5
(b)
22. The initial value of the decision variable for a Bresenham line can be twice delta y less delta x. What does this represent?
a. a line that “rises” twice as fast as it “runs”
b. a line that “runs” twice as fast as it “rises”
c. a line with a negative slope
d. (none of the above)
(d)
23. The cost for finding the location in the frame buffer for a point that is part of a DDA or Bresenham line is
a. constant
b. not the same for all points
(b)
24. What’s wrong with using the implicit equation for a circle as the basis for drawing the circle?
a. It generates irregularly spaced points along the circumference of the circle
b. It involves time-consuming calculations
c. Both (a) and (b)
d. Neither (a) nor (b)
(c)
25. What’s wrong with using the parametric equation for a circle as the basis for drawing the circle?
a. It generates irregularly spaced points along the circumference of the circle
b. It involves time-consuming calculations
c. Both (a) and (b)
d. Neither (a) nor (b)
(b)
26. What’s wrong with using the differential equation for a circle as the basis for drawing the circle?
a. It generates irregularly spaced points along the circumference of the circle
b. It involves time-consuming calculations
c. Both (a) and (b)
d. Neither (a) nor (b)
(d)
27. Points along ____ of the circumference of a circle need to be calculated using an equation for the circle or the Bresenham technique or something similar; the remainder can be determined by complementing and/or exchanging values.
a. ½
b. ¼
c. 1/8
d. 1/16
(c)
28. What’s wrong with using the Bresenham (a.k.a Midpoint) circle algorithm?
a. It generates irregularly spaced points along the circumference of the circle
b. It involves time-consuming calculations
c. Both (a) and (b)
d. Neither (a) nor (b)
(d)
29. The Midpoint circle algorithm generalizes to
a. Ellipses
b. Parabolas
c. Hyperbolas
d. (all of the above)
e. (none of the above)
(d)
30. The pixels plotted to represent the circumference of a circle should be _____ the circumference.
a. Inside
b. On (i.e. overlapping)
c. Outside
(a)
31. Screen coordinates should refer to pixel ______.
a. Centers
b. Corners
(b)
32. To generate intersections of polygon edges with scan lines for the scan-line polygon fill algorithm, “DDA” along edges, always stepping in
a. x
b. y
c. the axis of greater excursion
d. the axis of lesser excursion
(b)
33. For the scan-line polygon fill algorithm, vertices are treated as
a. no intersection at all
b. one intersection
c. two intersections
d. (it depends on the edges meeting at the intersection)
(d)
34. As you move around the perimeter of a polygon, suppose you encounter a falling edge, a horizontal edge, and then another falling edge. The two vertices at the ends of the horizontal edge should be treated as
a. no intersection at all
b. one intersection
c. two intersections
d. (it depends on the edges meeting at the intersection)
(a)
35. After you have found the intersection of one scan line with an edge of a polygon, finding the intersection of an adjacent scan line generally requires
a. an addition or subtraction
b. a multiplication or division
c. both (a) and (b)
(a)
36. The “active edge list,” as discussed in class, contains
a. only one edge at a time
b. all edges intersecting the current scan line
c. (b) and sometimes edges which do not intersect the current scan line
(c)
37. Suppose a point which may or may not be interior to a polygon is extended (as a ray) beyond the limits of the polygon, crossing 21 polygon edges in the process. The original point _____ inside the polygon.
a. was
b. was not
(a)
38. When the winding number for a point is zero, the point is _____ to the polygon.
a. exterior
b. interior
(a)
39. If the fill method is “up, down, left, right, and the four diagonal points”, then the boundary should be
a. four-connected
b. eight connected
c. (either (a) or (b))
(a)
40. A mouse can be used effectively to provide input only if the mouse responds linearly and consistently.
a. true
b. false
(b)
41. While a trackball is a two-dimensional positioning device, a spaceball is a three-dimensional positioning device which actually moves up, down, left, right, forward and backward.
a. true
b. false
(b)
42. What indicates the position and orientation of the hand in a data glove?
a. micropotentiometers
b. electromagnetic coupling
c. optical position sensors
(b)
43. The position of a cursor on a tablet can be determined by any of the following EXCEPT
a. embedded wires
b. changes in potential
c. electromagnetic resonance
d. acoustic techniques
e. (no exceptions here)
(e)
44. Touch panels employ ____ techniques.
a. optical
b. electrical
c. acoustical
d. (all of the above)
(d)
45. The position of the light pen is determined by
a. touch panel techniques
b. determining the location (on the monitor) of the beam of light emitted by the light pen
c. the light produced by the monitor and sensed by the light pen
d. electromagnetic coupling
(c)
46. Voice systems provide the best, overall, general-purpose graphical input.
a. true
b. false
(b)