Sample Questions 2 -Computer Graphics (ECSE-4750) - Fall 2005

Here are some sample questions for the final exam.

  1. What are the 3 basic elements of viewing? (see slide set 16)
  2. What is a projector, in the context of viewing?
  3. Does projection preserve straight lines?
  4. Does projection preserve angles?
  5. Tell me about the default OpenGL projection:
    1. where is the camera?
    2. in which direction does it point?
    3. what is the default view volume?
    4. what is the default projection matrix?
  6. What should we do to the camera or objects if we want to visualize objects with both +ve and -ve Z coordinates?
  7. Here is a 2D transformations question that will take some thinking. I want to move an object as follows:
    1. First, translate by 2 in X.
    2. Then rotate by 90 degrees about the origin.
    3. Then translate by 1 in Y.
    4. Than rotate by another 90 degrees about the origin.

    These 4 combined operations could be simplified into one translation followed by one rotation about the origin. What would this translation and rotation be?

    Alternatively, these 4 combined operations could be simplified into one rotation about the origin followed by one translation. What would this rotation and translation be?

  8. Compute the 4x4 homogeneous transformation matrix to translate and uniformly scale a volume with corners (1,2,3) and (4,5,6) to be centered in a cube with corners (0,0,0) and (1,1,1), and to be as large as possible.
  9. What is the difference between Gouraud and Phong shading?
  10. Can Gouraud shading produce a highlight in the interior of a face?
  11. Can Phong shading produce a highlight in the interior of a face?
  12. Is Gouraud shading faster than Phong?
  13. What is the rendering equation?
  14. Can the standard OpenGL pipeline easily handle light scattering from object to object?
  15. Can the rendering equation handle light scattering from object to object?
  16. How can a piece of plastic look white when the light glances off it, but look red when the light hits it straight on? In both cases, the incident light is white.
  17. Using ambient light is a simplification for what?
  18. Smooth and rough surfaces reflect light differently how?
  19. What is a Lambertian surface?
  20. How did Phong model surfaces of different shininess? I.e., what changed in his equation?
  21. Find a normal vector to the plane thru the 3 points: (0,0,0), (1,1,1), (2,2,2).
  22. Why does OpenGL requires you explicitly to enable shading, instead of having it on all the time?
  23. What's special about a spot light?
  24. Normalize the following vector: (3,4,12).
  25. What's an accumulation buffer good for?
  26. How can you use XOR to swap the numbers in 2 different registers?
  27. What's the difference between a bitmap and a pixelmap?
  28. Cohen-Sutherland clipping is efficient when most of the input lines have what property?
  29. Briefly describe Cohen-Sutherland clipping.
  30. Find the intersection point between the plane x+y+z=1 and the line x=y=z=t (t is a parameter).
  31. What is the Mach band effect?
  32. Briefly define antialiasing.
  33. What is mipmapping?
  34. Sort these coordinate systems in order that they process the data.
    1. parametric
    2. screen
    3. texture
    4. world
  35. What is the backward mapping problem in texture mapping?
  36. What is area averaging in texture mapping?
  37. What is a big problem with the painters algorithm?
  38. If your scene is fixed but your viewpoint changes, what is the name for a good tree preprocessing technique to display it?
  39. Do the Bresenham circle algorithm for a circle of radius 18.
  40. What property of the eye allows us to represent a color with 3 values?
  41. Give 4 reasons why color printers have black ink, even though printing cyan, magenta, and yellow on top of each other produces a form of black.
  42. In NTSC which of the three primary colors weighs the most in the luminance? Which weighs the least?
  43. Gamma describes what property of a CRT?
  44. Give the relative advantages and disadvantages of explicit, implicit, and parametric curves.
  45. Transform this parametric curve into an explicit one: x=t+1, y=t2
  46. What degree of continuity do you usually need at a joint between two spline curves so that the user can't see the joint?
  47. Give a parametric representation of a cylinder. Find the partial derivatives for a point on the surface. Take their cross product to find the normal vector at any point.
  48. What is one problem with interpolating a spline through the control points instead of approximating a spline near the points?
  49. Find the cubic parametric Bezier curve through these control points: (0,0), (1,0), (0,1), (1,1).
  50. Interpolate a quadratic explicit polynomial through these points: (0,0), (1,0), (2,1).