Computer Science 455
Instructor: R. P. Burton
Fourth Quiz
October 18-19, 2004
Name _________________________________________ Score ____________/37
1. Which technique is likely to use less storage for an image that contains several
square monochromatic areas?
a.cell encoding
b.run-length encoding
c.dithering
(a)
2. In order for a mouse to function meaningfully as an input device, it must respond
linearly.
a. true
b. false
(b)
3. In order for an input device to function at all, it must move (i.e. be movable).
a. true
b. false
(b)
4. Suppose a graphics tablet consists of 1024 embedded "left to right" wires and
1024 "top to bottom" wires, each with a code to identify it. What is the minimum
number of bits needed to identify a wire over which a "listening" stylus
is positioned?
a. 1
b. 9
c. 10
d. 11
e. 12
(a)
5. _____ can detect the position of a sound-emitting stylus on a 2D surface.
a. Two point microphones at adjacent corners
b. Two strip microphones along adjacent edges
c. Either (a) or (b)
(c)
6. How many point microphones are needed to determine the position of a sound-
emitting stylus in 3D space?
a. two
b. three
c. four
d. five
(b)
7. Touch panels employ _____ methods.
a. optical
b. electrical
c. acoustical
d. all of the above
(d)
8. A light pen _____ light.
a. emits
b. detects
(b)
9. The optimal, general purpose graphics input system is a voice system.
a. true
b. false
(b)
10. Ink-jet printers squirt ink which is deflected electrically.
a. true
b. false
(a)
11. The drawing device in a mechanical plotter is a
a. felt-tipped pen
b. a pen tip (sans (without) ink) which impresses the paper
c. a laser
d. a carbide-tipped stylus
e. any of the above
(e)
12. The primary objective of graphics standards is
a. order for order's sake
b. control
c. making money by excluding nonconformists
d. portability
(d)
13. A bit-block transfer or a pix-block transfer, from one area of the frame buffer to
another, can be done in general without using additional memory only if
a. the blocks are not rotated relative to one another
b. the blocks are rotated only by multiples of 90 degrees
(a)
14. It is impossible to produce an apparent 3D image (actually 2.5D) using only our
eyes and a flat, 2D screen. Some static, mechanical, optical, electrical¡Ä device
must be used to separate the left-eye image from the right-eye image.
a. true
b. false
(b)
15. How many of the following devices/techniques produce true 3D output (as
opposed to two or more 2D images which the mind combines to suggest 3D):
holograms, rotating LED panels, bimodal projection, head-mounted displays,
varifocal mirrors, and stereolithography.
a. none
b. one or two
c. three or four
d. five or six
(b)
16. The "twinklebox" used one spinning disk, one photomultiplier tube, and one LED to determine
a. the location of a point in 3D space
b. a line containing a point in 3D space
c. a plane containing a point in 3D space
(c)
17. Originally mice were mostly useless, in part because they were "off screen"
devices and in part because they did not respond consistently and predictably to
user actions. Only when mice came to respond consistently and predictably did
they become useful input devices.
a. true
b. false
(b)
18. Voice input (to a graphics system) is most appropriate when the "logical input device" is a
a. locator
b. stroke
c. keyboard
d. pick
(d)
19. The logical input devices discussed class can be provided by _____ of the physical input
devices discussed in class.
a. typically just one
b. only about half
c. most, but not all
d. all
(d)
20. In request mode, which entity determines what will happen next?
a. the user
b. the program
(b)
21. In sample mode, which entity determines what will happen next?
a. the user
b. the program
(b)
22. In event mode, which entity determines what will happen next?
a. the user
b. the program
(a)
23. To produce a horizontal line, the mouse can be clicked twice, once at each endpoint.
Each click provides two coordinates (one for x and one for y). The horizontal line is
determined by a total of ____ coordinates.
a. two
b. three
c. four
(b)
24. A rubber band line can be provided by all of the following EXCEPT
a. XOR
b. copy-and-save background, write line, restore background¡Ä
c. a dedicated bit plane
d. dithering
e. (no exceptions here)
(d)
25. A vase is traced using a 3D input device. The application is _______
a. analytic
b. synthetic
(a)
26. An imaginary vase is traced using a 3D input device. The application is ______
a. analytic
b. synthetic
(b)
27. The graphics user should think in terms of Cartesian coordinates, period. Other
coordinate systems simply are not appropriate for graphics.
a. true
b. false
(b)
28. In a 2D projection of a 3D wireframe, wider lines appear _____ to all viewers.
a. closer
b. farther away
c. (neither (a) nor (b) is true for all viewers)
(c)
29. A parallel projection is oddly named, because it assumes that your viewing
direction is perpendicular to the viewing surface.
a. true
b. false
(b)
30. A graphics expert system is a system
a. where the user interacts via a GUI (graphical user interface)
b. where the system "observes" and adapts based on the user's actions
c. with voice input
(b)
31. At a minimum, any coordinate system used for graphic presentation must require independent axes to be perpendicular to each other.
a. true
b. false
(b)
32. Suppose you determine the planar coefficients (A, B, C, and D) using three points,
each with coordinates x, y, and z. Now suppose the three points are transformed
(translated, rotated, scaled, sheared, etc.) by some matrix M. The new planar
coordinates, based on the transformed points
a. are determined by postmultiplying the original (A,B,C,D) by M
b. are determined by premultiplying the original (A,B,C,D) by M
c. are determined by postmultiplying the original (A,B,C,D) by M-inverse
d. are determined by premultiplying the original (A,B,C,D) by M-inverse
e. cannot be determined using M
(c)
33. What is a superquadric?
a. a quadric surface in 4D
b. a composition of quadric surfaces
c. a quadric with additional parameters to increase flexibility
(c)
34. What is most likely to be preserved in a blobby object?
a. shape
b. volume
c. topology
d. shape and topology
e. volume and topology
(e)
35. What is a principal advantage of a parallel projection?
a. It preserves relative dimensions
b. The direction of projection is perpendicular to the viewing surface
c. It produces realistic views
(a)
36. What is a principal advantage of perspective projection?
a. It preserves relative dimensions
b. The direction of projection is perpendicular to the viewing surface
c. It produces realistic views
(c)
37. Pick the true statement:
a. An axonometric projection is an isometric projection.
b. An isometric projection is an axonometric projection.
c. A projection can be axonometric or isometric, but not both.
(b)