A directory of Objective Type Questions covering all the Computer Science subjects. Here you can access and discuss Multiple choice questions and answers for various compitative exams and interviews.

31. Consider the Breshenham’s line generation algorithm for a line with gradient greater than one, current point (xi, yi) and decision parameter, di. The next point to be plotted (xi+1, yi+1) and updated decision parameter, di+1, for di < 0 are given as .................

(A) xi+1 = xi+1
yi+1 = yi
di+1 = di + 2 dy

(B) xi+1 = xi
yi+1 = yi + 1
di+1 = di + 2 dx

(C) xi+1 = xi
yi+1 = yi + 1
di+1 = di + 2 (dx – dy)

(D) xi+1 = xi + 1
yi+1 = yi + 1
di+1 = di + 2 (dy – dx)
a. A
b. B
c. C
d. D
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Answer: (b).B

32. A point P(2, 5) is rotated about a pivot point (1, 2) by 60°. What is the new transformed point P'?
a. (1, 4)
b. (–1, 4)
c. (1, – 4)
d. (– 4, 1)
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Answer: (b).(–1, 4)

33. In perspective projection (from 3D to 2D), objects behind the centre of projection are projected upside down and backward onto the view-plane. This is known as ..............
a. Topological distortion
b. Vanishing point
c. View confusion
d. Perspective foreshortening
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Answer: (c).View confusion

34. The Liang-Barsky line clipping algorithm uses the parametric equation of a line from (x1,y1) to (x2,y2) along with its infinite extension which is given as :

x = x1 + Dx.u
y = y1 + Dy.u

Where Dx = x2 – x1, Dy = y2 – y1, and u is the parameter with 0 ≤ u ≤ 1. A line AB with end points A(–1, 7) and B(11, 1) is to be clipped against a rectangular window with xmin=1, xmax=9, ymin=2, and ymax=8. The lower and upper bound values of the parameter u for the clipped line using Liang-Barsky algorithm is given as:
a. (0, 2/3)
b. (1/6, 5/6)
c. (0, 1/3)
d. (0, 1)
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Answer: (b).(1/6, 5/6)

35. Consider the Breshenham’s circle generation algorithm for plotting a circle with centre (0,0) and radius ‘r’ units in first quadrant. If the current point is (x1,y1) and decision parameter is pi then what will be the next point (xi+1,yi+1) and updated decision parameter pi+1 for pi ≥ 0
a. xi+1 = xi + 1               yi+1 = yi            pi+1 = pi + 4xi + 6
b. xi+1 = xi + 1               yi+1 = yi - 1      pi+1 = pi + 4(xi - yi) + 10
c. xi+1 = xi                     yi+1 = yi - 1      pi+1 = pi + 4(xi - yi) + 6
d. xi+1 = xi - 1                yi+1 = yi            pi+1 = pi + 4xi + 10
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Answer: (b).xi+1 = xi + 1               yi+1 = yi - 1      pi+1 = pi + 4(xi - yi) + 10

36. A point P(5,1) is rotated by 90 degrees about a pivot point (2,2). What is the coordinate of new transformed point P’ ?
a. (3,5)
b. (5,3)
c. (2,4)
d. (1,5)
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Answer: (a).(3,5)

37. Let R be the rectangular window against which the lines are to be clipped using 2D Sutherland-Cohen line clipping algorithm. The rectangular window has lower left-hand corner at (-5,1) and upper right-hand corner at (3,7). Consider the following three lines for clipping with the given end point co-ordinates:

Line AB: A(-6,2) and B(-1,8)
Line CD: C(-1,5) and D(4,8)
Line EF: E(-2,3) and F(1,2)

Which of the following line(s) is/are candidate for clipping?
a. AB
b. CD
c. EF
d. AB and CD
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Answer: (d).AB and CD

38. In perspective projection, if a line segment joining a point which lies in front of the viewer to a point in back of the viewer is projected to a broken line of infinite extent. This is known as ...................
a. View confusion
b. Vanishing point
c. Topological distortion
d. Perspective foreshortening
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Answer: (c).Topological distortion

39. Which of the following statement(s) is/are correct with reference to curve generation?

I. Hermite curves are generated using the concepts of interpolation.
II. Bezier curves are generated using the concepts of approximation.
III. The Bezier curves lies entirely within the convex hull of its control points.
IV. The degree of Bezier curve does not depend on the number of control points.
a. I, II and IV only
b. II and III only
c. I and II only
d. I, II and III only
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Answer: (d).I, II and III only

40. Which of the following is used for the boundary representation of an image object?
a. Quad Tree
b. Projections
c. Run length coding
d. Chain codes
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Answer: (d).Chain codes

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