CS 381 Fall 2012
Quiz Topics After the Midterm

Below are all of the possible quiz topics that were posted on the class webpage following the Midterm Exam.

For a complete list of quiz topics for the semester, see also Quiz Topics Before the Midterm.

• Name and briefly explain each of the three parts in the Phong Model.
• In the Phong Model, when we add the colors from the three parts, the result may have components greater than \(1\). What is the standard way of dealing with this?
• Explain how the specular computation is done in the Blinn-Phong Model.
• What is “Phong interpolation”?
• How do we compute the facet normal of a triangle? Give a formula.
• In the context of the rendering pipeline, what is “culling”?
• Where in the pipeline does culling occur? Be specific.
• When we light the back side of a polygon, the normal generally points in the wrong direction. How do we deal with this?
• Briefly explain the computation involved in quadratic attenuation.
• What is a “texture”?
• After the call to glTexImage2D or gluBuild2DMipmaps, the texture is server-side data. What practical ramifications does this have?
• What is a GLSL “sampler” variable?
• What are “mipmaps”?
• What do we usually do with the texture transformation?
• What is “billboarding”?
• Briefly explain how we rotate a vector so that it becomes parallel with a given vector. (What angle do we rotate through, and what axis do we rotate about?)
• What is “bump mapping”?
• When we do bump mapping, we need to provide our shaders with a piece of information that they do not normally receive. What is this piece of information? Why is it needed?
• What is “reflection mapping”? Be specific!
• Give two problems with using a sphere map.
• What is a “cube map”?
• What is an “environment map”?
• Environment-map-based reflection mapping can produce results that are inaccurate in a number of ways. Explain one.
• What is the “index of refraction” of a material?
• When a beam of light enters a denser medium (say, when moving from air to glass), how does its direction change?
• What causes chromatic aberration?