Computer Science 455
Quiz 6
March 30-31, 2009
Instructor: R. P. Burton

1. Halftoning is most likely to be useful when the resolution of the ______ exceeds the resolution of the ______.
        a. data, display device
        b. display device, date
        c. either (a) or (b)
(a)

2. Suppose the pixels are treated as being 4 x 4 and each original pixel can have four levels of intensity. How many different levels of intensity can a “4x4” pixel have? (pick the range in which the answer lies)
        a. 0-15
        b. 16-50
        c. 51-100
        d. more than 100
(b – 49)

3. Dithering is most like
        a. supersampling
        b. area sampling
        c. halftoning
        d. adding noise
(d)

4. Constant shading of multiple facets (surfaces) of an object may be inexpensive, but it is virtually never realistic.
        a. true
        b. false
(b)

5. Where does Gouraud shading first calculate intensities?
        a. on surfaces
        b. at vertices
        c. along edges
        d. across scan lines
(b)

6. Where does Phong shading first calculate intensities?
        a. on surfaces
        b. at vertices
        c. along edges
        d. across scan lines
(d)

7. Instead of processing the infinitely many points which could be generated over the surfaces in a scene, raytracing finds the color of each pixel on the screen.
        a. true
        b. false
(a)

8. Raytracing accommodates all of the following EXCEPT
        a. intersurface reflection
        b. transparency
        c. refraction
        d. (no exceptions here)
(d)

9. What is the maximum number of rays that can be sent into a scene?
        a. slightly less than the number of pixels
        b. exactly the same as the number of pixels
        c. slightly more than the number of pixels
        d. substantially more than the number of pixels in the scene
(d)

10. A scene represented using an octree has forfeited the ability to determine – or even estimate – surface normals.
        a. true
        b. false
(b)

11. Fractalization of a surface can be characterized properly as micropolygonization of the surface, literally generating lots and lots of polygons in lieu of a single polygon.
        a. true
        b. false
(a)

12. Radiosity models
        a. primarily specular reflection
        b. primarily diffuse reflection
(b)

13. Radiosity calculates surface illumination in a view-________ manner.
        a. dependent
        b. independent
(b)

14. If two curve sections have zero-order continuity
        a. they do not touch
        b. they touch
        c. their tangents match where they touch
        d. their curvatures match where they touch
(b)

15. Parametric equations are suitable not only for curves, but also for surfaces and solids (and, conceivably, hypersolids).
        a. true
        b. false
(a)

16. In general and in a graphics context, there is increased net benefit from curves which ________ the control points.
        a. approximate
        b. interpolate
        c. (there’s no difference; “approximate” and “interpolate” are equivalent activities)
(a)

17. The Bezier techniques were developed
        a. for the design of ships hulls
        b. for the design of automobiles
        c. for the design of aircraft
(b)

18. Like the Bresenham algorithms, the Bezier coordinate function can be shown to be algebraically correct, but it is largely devoid of intuitive meaning.
        a. true
        b. false
(b)

19. For 3 sets of 4 control points each, how many blending functions need to be determined?
        a. 3
        b. 4
        c. 3 x 4
        d. (none of the above)
(b)

20. The convex hull property assures that
        a. the Bezier curve passes through the control points
        b. the Bezier curve is contained “within” the control points
        c. the control points are contained “within” the Bezier curve
(b)

21. Bezier curves are
        a. always open
        b. always closed
        c. sometimes open and sometimes closed, but only zero-order continuity can be achieved
        d. sometimes open and sometimes closed, and first-order continuity can be achieved
(d)

22. The degree of Bezier curve is
        a. fixed
        b. not fixed, but dependent on the number of control points
        c. not fixed, but independent of the number of control points
        d. determined by the precision with which the curve is to be drawn
(b)

23. ____________ have blending functions which are defined recursively.
        a. Bezier curves
        b. B-spline curves
        c. Both (a) and (b)
(b)

24. The degree of B-spline curve is
        a. fixed
        b. not fixed, but dependent on the number of control points
        c. not fixed, but independent of the number of control points
        d. determined by the precision with which the curve is to be drawn
(c)

25. As a general rule, you get the convex hull property ____ the variation diminishing property.
        a. and
        b. (exclusive) or
(a)

26. Visible light is _______ the electromagnetic spectrum.
        a. a narrow frequency band within
        b. about half of
        c. the majority of
        d. the entirety of
(a)

27. The frequencies emitted by the sun are
        a. toward the “infrared” end of the spectrum
        b. toward the “ultraviolet” end of the spectrum
        c. across the entire visible spectrum
(c)

28. What is the dominant frequency of red light?
        a. red
        b. the complement of red
        c. everything but red
(a)

29. Which of the following is the most pure “color”?
        a. red
        b. white
        c. black
(a)

30. Which of the following are NOT complementary colors?
        a. black and white
        b. red and cyan
        c. green and magenta
        d. blue and yellow
        e. (all are complementary color pairs)
(a)

31. What is the optimal number of primary colors, where “optimal” means that the number of colors in the color gamut divided by the number of primary colors is maximized?
        a. two
        b. three
        c. four
        d. infinitely large
(b)

32. The “standard primary colors” come from
        a. mother nature
        b. the work of Roy G. Biv
        c. a committee
(c)

33. Red, green, and blue, for screen phosphors, are chosen primarily to maximize coverage of the chromaticity diagram.
        a. true
        b. false
(b)

34. Artists create _____ by starting with pure hues and adding black pigment.
        a. shades
        b. tones
(a)

35. When a triangle is “swept” translationally to create a triangular prism, how many polygons should result?
        a. just one
        b. two or three
        c. four or five
        d. more than five, but less than 60.
        e. Infinitely many, depending on the intended precision
(c)

36. Sweeps of all the following varieties can occur EXCEPT
        a. rotational
        b. along Bezier curves
        c. those which include scaling
        d. those which include shearing
        e. (no exceptions here)
(e)

37. In the RGB model, white represents _____ red, green, ___ blue.
        a. full, and
        b. no, or
(a)

38. In the CMY model, white represents _____ red, green, ___ blue.
        a. full, and
        b. no, or
(b)

39. Where are the tints in the HSV color model?
        a. on the “plateau” at the top
        b. on the sides
        c. on the central axis
        d. in the interior
(a)

40. Where are the tints in the HLS color model?
        a. on the “plateau” at the top
        b. on the sides
        c. on the central axis
        d. in the interior
(b)

41. The pinhole in a pinhole camera is the counterpart of ___ in the raytracing model.
        a. the eye
        b. a pixel
(a)

42. In the raytracing model, each pixel can be thought of as an independent window into the scene.
        a. true
        b. false
(a)