Midterm Review
CS 445: Computer Graphics

The midterm will be held Tuesday, Oct 28, 2008.

Review class notes, online notes, labs, and relevant sections in textbook.

Topics

• Ray Tracing

  • Set up of world: camera, screen, world coordinates vs pixel coordinates.
  • Pseudo code for the basic algorithm.
  • What is a ray and how is it represented mathematically?
  • Computing intersections with simple objects: spheres, planes, cylinders, ...
  • How is color computed at intersection point using the Phong lighting model?
  • How are shadows implemented?
  • How are reflections implemented?

• OpenGL Pipeline, Structure and Transformations:

  • You should be able to write simple OpenGL code,e.g. the types of functions that go into the display method or init method. For example, begin by reviewing the openGL commands listed in the Summary of OpenGL functions for setting up Transformations.
  • Understand how the ModelView Matrix is changed with openGL commands such as glLoadIdentity, gluLookAt, glTranslate, etc
  • Geometry Primitives
  • OpenGL Command Format
  • 3D Rendering Pipeline - what is the sequence of operations and transformations. Terminology: model/local coordinate system, world coordinate system, view coordinate system, screen space, clipping, back plane, front plane, perspective transform

• Color and Lighting

  • Color Representation.
  • Color formats
  • How is lighting modeled in openGL?
  • How are normals calculated for basic polygon shapes?
  • Color Ramps
  • Anti-Aliasing - what is aliasing and how do anti-aliasing techniques work?

• Efficiency Issues - Under standing the basic differences and motivation for items below. Except for immediate mode, you don't have to know details of openGL code, but you do need to understand how they differ with respect to openGL client-server model:

  • Immediate mode
  • Display Lists
  • Vertex Arrays - understand indexing structure of arrays.
  • Vertex Buffer Objects

• Geometric Objects and Transformations

  • Scalars, Points and Vectors - what are they and what operations are allowed between them?
  • Vectors: representation, length, addition, scalar multiplication, dot products, cross products.
  • Matrix Operations: multiplication, addition, determinants, transpose, inverse (of standard transformations such as rotations, translations,scale), identity.
  • 2D Transformations: Translation, scaling, rotation, shear, reflection, projection. See web notes.
  • 3D Transformations: Translation, scaling, rotation, shear, reflection, projection. See in-class notes and textbnook.
  • Composition of transformations.
  • Homogeneous coordinates. What are they, why are they used?
  • 3D Transformations in opengl using the ModelView Matrix.
  • Coordinate systems - right/left handed

• Setting up controls for avigation through a scene

• Scene graphics - be able to create the scene graph for a particular scene (e.g. solar system, robotic arm, etc). Review lab asignment and chapter in textbook.

• Viewing

  • Look at Nate Robbins projection.exe (gluPerspective, gluLookAt)
  • Camera frame: View Reference Point (VRP), view-up vector (VUP), view-plane normal (VPN)
  • Perspective projection and perspective transform.
  • Terminology: culling, hidden surface removal, z-buffer, view frustum.