Exam Topics and Notes

• midterm
• final

• Closed book, closed notes
• Most of what you are responsible for we have have covered in class. However, I expect you to have read the book along with the class - mainly to pick up terminology and the details about OpenGL programming. Stuff that could be on a test that we did not explicitly cover in class includes defining some terms (in bold from the text) and explaining OpenGL commands (that you would have used in your labs).
• Write down answers that convince me you know what you're talking about. Some questions will require short discussions - I'm looking for the reasons that you gave an answer, not so much the answer itself.
• For transformation matrices, you don't need to multiply the matrices out. If you set up the transformation matrices correctly, that will get you credit.
• I expect you to know the simple equations that we've covered in class such as dot product.
• I don't expect you to memorize or derive the more complex equations e.g., perspective projection, cross-product - but you should be able to talk about the qualities of the calculation.
• you should be able to
  • explain an equation that we covered in class if I give it to you, and
  • tell me in words what the equation does and how it does it if I don't give it to you but just ask you about it.
• Be able to intelligently discuss issues. When there are various ways to do things you should know the alternatives and be able to compare advantages and disadvantages of each.
• Types of questions
  • define terms (single phrase) or explain a term (more detail wanted)
  • write small piece of OpenGL code similar to lab assignment
  • write transformation matrices to do X - you can use a notation to indicate what the matrix does - the actual 4x4 matrix is not necessary - but be specific enought so that there is no ambiguity
  • describe features of operation or procedure
  • explain equations
  • describe a procedure for doing X

Midterm

Midterm Topics

• Graphics systems
  • Basic Graphics Technology (chapter 1-3), for example,
    • terminology
    • display devices: CRT, LCD, LED, Plasma, DLP
    • input devices
    • ray tracing
    • z-buffer
    • rasterization
  • Viewing pipeline: spaces and the transformations between them
    • application space / object space
    • world space
    • eye space
    • image space (device independent coordinate system) / clip space
    • viewport / screen space / pixel space
• OpenGL architecture, for example
  • state machine
  • event driven
  • callback routines
  • idle function
  • support for user interaction (glut)
  • matrix stack
• OpenGL viewing & programming
  • Setup: e.g., Depth test, buffer commands
  • ModelView matrix
    • gluLookAt
    • scale, rotate, translate
  • Projection matrix
    • glOrtho
    • gluOrtho2d
    • gluPerspective
    • glFrustum
  • Front face, back face, vertex ordering
  • Viewport command
  • Begin-End types
  • Vertex
  • display list commands
  • Interaction
    • mapping screen space back to object space
    • mouse movements
    • keyboard processing
• Transformations (2D/3D)
  • properties of scale, rotate, translate, shear, affine
  • matrix representations: 4x4
  • homogeneous representation
  • composite transformations
  • hierarchical animation
  • transformation between coordinate systems
  • rigid transformations
  • projections: perspective, orthogonal
  • viewport mapping
• Color & Illumination
  • Color spaces: RGB, CMY, CIE, HSL
  • tristimulus theory of color
  • gamut
  • metamers
  • response of visual system, rods, cones, perceptual space
  • local v. global illumination, radiosity, ray tracing
  • Ambient, Diffuse, Specular
  • Lambert's Law
  • Light sources: point, spot, directional

Approximate point distribution (+/- 5%)

Sample questions

• Define the following terms: display processor, API, shadow mask, vector display
• What does the following OpenGL command do: glEnable(GL_DEPTH_TEST)
• In the OpenGl viewing pipeline, describe eye space. Give the two normal vectors for the following polygon: (-1,0,-1), (-1,0,1), (1,0,1), (1,0,-1)
• For 2D graphics, write the code to rotate a cube, located at (2,4) about its center by 45%
• Set up the transformation between coordinate systems. e.g., to define a point P in a camera coordinate system defined by: Given u = (-1,0,1), v = (1,1,0), w = (.24, 0.45, -.34), O = (3,-5,4)>
• For 3D graphics, write the code to scale a cube along its local x-axis, located at (2,4) and already rotate by 45% around the z-axis
• In OpenGl, with the eye at (0,0,10) looking at the origin, give an up vector that would produce a head tilt to the right of 45 degrees.
• Are 2D rotation matrices commutative?
• Are 3D rotation matrices commutative?
• What is global illumination?
• What is the CMY color space
• What is the tristimulus theory of color?

Final Exam

• be comprehensive
• have more of an emphasis on material not covered on the midterm
• emphasize programming segments that involve OpenGl commands - similar to labs
• cover the 'under the hood' discussions of transformations and spaces involved in the graphics pipeline
• have a list of the OpenGl commands you'll need to answer the questions.

Final Topics

1. "Under the hood" - graphics pipeline: Be able to explain (to the extent we've covered it in class) the processing that z-buffer algorithms (like OpenGL) do in processing geometric data to create a 3D rending.
   • 2D viewing, viewport mapping
   • 3D transformations: homogeneous coordinates
   • world-to-eye space transformation
   • clipping
   • 3D viewing: perspective projection: 4x4 matrices
   • rasterization & interpolation
   • Z-buffer Visible surface algorithms: color & depth buffer
   • z-buffer v. ray-tracing
2. "Under the hood" - shading:
   • Illumination types: ambient, diffuse, specular
   • Illumination: material properties, light source properties
   • Texture mapping: image & procedural; texture coordinates
   • Transparency & the alpha channel, and stippling
   • Gouraud smooth shading, Phong smooth shading
3. OpenGL and lab programming: This will consist of small program segments to do a variety of tasks that are similar to things you've done in the lab assignments. Use pseudo-code for non-OpenGL commands as directed.
   • use of color and depth buffers
   • double buffering
   • using the timer command: glTimerFunc
   • transformations including hierarchical organization
   • setting up the eye: polar coordinates, first person mode: glLookAt, gluFrustum, glPerspective
   • light model: point, hooded, directional: glLight, glLightModel
   • material properties, illumination, and shading: ambient, diffuse, specular, emission, smooth shading, normals
   • setting up projection: orthogonal & perspective: glPerspective, glOrtho2d, glOrtho
   • working with the stencil buffer to apply polygonal decals
   • working with textures: setting up texture mapping: glTextureCoord
   • transparency & stippling
   • billboarding
   • first person view
   • picture-in-picture
4. Other graphics knowledge: Including terms in the first 3 book chapters and other topics we covered in class.
   • Basic Technology: frame buffer, displays, color look-up tables, etc.
   • Basic Graphics Terminology: vector refresh, pointing devices, etc.
   • Ray tracing
   • Color: tristimulus theory, metamers, color spaces, additive v. subtractive
   • Geometric modeling: computing normals, triangulation, etc.
   • Animation: physics-based, mocap, keyframe, FK/IK, etc.
   • Shaders: vertex, fragment

Approximate point distribution (tentative)

Sample questions

• Define the following terms: CSG, subdivision surfaces, stippling, compositing.
• Describe the operations performed on the Stencil Buffer when implementing decals.
• In the OpenGl viewing pipeline, describe the transformations that take data from world space to device independent coordinate system.
• Give the glFrustum command that is the equivalent to the given glPerspective command
• Write the OpenGl commands to write for 3D graphics to rotate a cube, located at (2,4,0) about its center by 45% around a line parallel to the x-axis.
• Set up the transformation between coordinate systems. e.g., to define a point P in a camera coordinate system defined by: Given u = (-1,0,1), v = (1,1,0), w = (.24, 0.45, -.34), O = (3,-5,4)
• For 3D graphics, write the code to scale a cube along its local x-axis, located at (2,4) and already rotate by 45% around the z-axis
• In OpenGl, with the eye at (0,0,10) looking at the origin, give an up vector that would produce a head tilt to the right of 45 degrees.
• Describe the use of the alpha channel in compositing
• What is the difference between alpha blending and stippling?
• When using a depth buffer, how is the depth handled for a semi-transparent surface?
• How is a billboard aligned with the eye/camera?
• write the OpenGL commands to animate a chair on a ferris wheel. Assume theta is the rotation of the ferris wheel and the chair must remain upright with respect to the ground. Given:
  • the ferris wheel is drawn at the origin facing in the positive x-axis direction.
  • the ferris wheel radius is 10 meters, the chair ferris wheel pivot is at (0,10,0) relative to the chair
  • the center of the ferris wheel is at 0,40,0 and rotates around the x-axis
  Give the code that comes before drawing the ferris wheel chair:

    ...
    draw_ferris_wheel_chair()   // contains glVertex commands to draw the chair
  

• write the OpenGl commands to set up sun-like light source
• How does OpenGL determine if a face is facing front to the camera?
• How does OpenGL determine if a light source calculation should be performed on a face?
• How does OpenGL do Gouraud smooth shading?
• How does Phong smooth shading compare to Gouraud smooth shading?
• What transformations do vertex coordinates go through in order to be mapped onto the screen?
• What is the advantage of using the HSV color system?
• What is does a vertex shader do in a GPU?
• What is Constructive Solid Geometry?
• What is Mip-Mapping and how is it used in OpenGL?
• What problems are there in dealing with an arbitrary polygon when calculating the normal vector as the cross product of two edges?