TEST 3 - CS458

Instructor Dr P Juell                         NAME_______________________ 
CLOSED BOOK                                             Dec 6, 2000
100 points         

1. (20) For each of these pairs we want to know if Yes you can tell images apart generated by the two techniques (YES). Or if the images would be virtually indistinguishable, then NO you can not tell them apart (NO).
   • _____ wire frame depth cuing AND painter's algorithm

   • _____ each object having its own color AND shading using the diffuse light formula

   • _____ Gouraud shading AND Phong shading

   • _____ z-buffer AND painter's algorithm

   • _____ shading using the diffuse light formula AND shading using the combined diffuse and spectral formula

2. (20) For the following the color notation, the three values and the color are specified. For example in HSV (0,1,1) is Red. What are the following colors:
   • RGB (0,0,1) ___________

   • CMY (1,1,1) ___________

   • HSV (1,0.5,0) _________

   • HSV (0,0,0) ___________

   • HSV (0,0,0.5) _________

   • RGB (0.5,0.5,0.5) ______

   • RGB (1,1,1) ___________

   • RGB (0,0,0) ___________

   • CMY (0,0,1) ___________

   • RGB (1,0.5,0.5) ________

3. (10) Why would ray tracing and a technique such as z-buffer produce different results. Note they do not use different formulas.

4. (10) What would you have to do to correctly show a 3 inch cube of glass that you would not have to do for a 3 inch cube of wood? (Note there is more than one part for this question).

5. (10) Why do we normally use dithering rather than halftoning for computer output? (Not the newspaper version of halftoning, but the corresponding computer technique).

6. (10) What is the normal relationship between generated image quality and time required for computation? Discuss this briefly, identifying at least three techniques and why they cost as much or as little as they do.

7. (10) What will you get if you use Phong shading techniques on a cube?

8. (10) How might you get good looking specular highlights on dull wood, semi-shiny skin and shiny eyes. The easiest way to answer this is to give the important part of the formula and approximate values.