Computer Science 455 Instructor: R. P. Burton First Quiz September 13-14, 2004 Name _________________________________________ Score ____________/28 1.The application of computers in virtually every discipline was recognized at the time of the invention of computers. Similarly, the application of computer graphics was recognized with the advent of computer graphics. a.True b.False (b) 2.Two- and three-dimensional graphs and charts are tools with which practitioners in virtually all professions are conversant, suggesting that humans are innately able to read graphs and charts. a.True b.False (b) 3.The application of computers to the design (of automobiles, aircraft, and other manufactured products) was a(n) ________ use of computer graphics. a.early b.medium-term c.recent (a) 4.The application of computers to residential architectural was a(n) ________ use of computer graphics. a.early b.medium-term c.recent (b) 5.Simulation of environments using computer graphics is meaningful only to the extent that reality is simulated (accurately reflecting the laws of physics). a.True b.False (b) 6. Computer animation is limited to the entertainment sector (movies, computer games, etc.) a. True b. False (b) 7. “Image processing” and “computer graphics” are a. synonyms b. opposite ends of a common spectrum c. unrelated subdisciplines d. subset and superset, respectively e. superset and subset, respectively (b) 8.One of the many byproducts of the “computer revolution” was the invention of the CRT. a.true b.false (b) 9.What is the purpose of the cathode in a CRT? a.To aim electrons at specific screen locations b.To form electrons into a narrow beam c.To produce electrons d.To increase or decrease the flow of electrons (c) 10.Why are the phosphors in a CRT red, green and blue? a.because those are the standard primary colors (and all colors found in nature are combinations of those colors) b.because phosphor mined from phosphor mines is most readily available in those colors c.to accommodate the human visual system (which is particularly compatible with those colors) (c) 11.Photons are emitted from the phosphor coating on the screen a.only during electron bombardment b.only after electron bombardment ceases c.both during and subsequent to bombardment (c) 12.Why are high persistence phosphors not used? a.there are advantages to phosphors which fade quickly b.high persistence phosphors are inordinately expensive c.it is difficult to prevent “bleeding” to adjacent screen locations with high persistence (a) 13.Which of the following anticipate(s) a frame buffer? a.a raster-scan CRT b.a random-scan CRT c.both (a) and (b) (a) 14.Which is more vulnerable to burn? a.a raster-scan CRT b.a random-scan CRT c.neither is more vulnerable than the other (b) 15.Raster-scan CRTs must produce images by selecting from among discrete screen locations, unavoidably producing stair-step lines. a.true b.false (a) 16.Which is likely to offer the broader spectrum of colors? a.a beam-penetration CRT b.a shadow-mask CRT c.a plasma panel (b) 17.Which has the larger number of electron guns? a.a beam-penetration CRT b.a shadow-mask CRT c.(neither (a) nor (b); they both have only one electron gun) (b) 18.Which of the following has been the most significant advantage of the plasma panel? a.selective writing and erasure b.high resolution c.rich color gamut (a) 19.What is the true dimensionality of a “point” when projected by a CRT onto a screen? a.zero b.one c.two d.three (c) 20.What is the true dimensionality of a “line segment” when projected by a CRT onto a screen? a.zero b.one c.two d.three (c) 21.What are the “jaggies”? a.a British rock group, contemporary in popularity with the Beatles. b.A group of enthusiasts for a particular British sports car. c.The pixel jitter phenomenon produced by residual deflection magnetism. d.The “stair steps” the result from drawing on a discrete pixel grid. e.Variations in line segment thickness as a consequence of using the symmetric DDA algorithm (d) 22.If the DDA algorithm is used to draw a line from (100,200) to (-300, 400) including both endpoints, setPixel (x,y) is called between _____ times. a. 0 and 250 b.251 and 350 c.351 and 450 d.451 and 550 e.551 and 650 (c) 23.If a symmetric DDA algorithm is used to draw a line from (100,200) to (-300, 400) including both endpoints, setPixel (x,y) is called between _____ times. a. 0 and 250 b.251 and 350 c.351 and 450 d.451 and 550 e.551 and 650 (d) 24.If a Bresenham algorithm is used to draw a line from (100,200) to (-300, 400) including both endpoints, setPixel (x,y) is called between _____ times. a. 0 and 250 b.251 and 350 c.351 and 450 d.451 and 550 e.551 and 650 (c) 25.An unavoidable consequence of the DDA algorithm is that, instead of plotting pixels as close as possible to the true line, it plots pixels either overlapping or below the true line, “shifting” the representation of the line slightly downward. a.true b.false (b) 26.To what does the decision variable in the Bresenham algorithm most closely relate? a.the number of pixels written to the frame buffer so far b.the number of pixels remaining to be written to the frame buffer c.the slope of the line d.which of the two candidate pixel centers is closest to the true line e.an algebraic derivation with no obvious intuitive meaning (d) 27.A deficiency of the Bresenham algorithm is that it works efficiently only for lines with positive slopes less than or equal to 1. a.true b.false (b) 28.For purposes of the scan line polygon fill algorithm each vertex of a polygon is treated as ____ intersection point(s) with a scan line. a.0 b.1 c.2 d.sometimes one and sometimes 2 (d)