CS 184: COMPUTER GRAPHICS

Lecture #20 -- We: 4/7, 1999.

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Preparation:

Read:  Ch 11.1 "Representing Curves and Surfaces; Polygon Meshes",
  Ch 11.2.2 "Bezier Curves", Ch 11.3.2 Bezier Surfaces.
  Ch 20.0 Advanced Modeling Techniques, Ch 20.2 "Procedural Models".
 

PREPARATION FOR MIDTERM (next Wednesday !)

The time to prepare for the midterm exam is NOW -- not Tuesday night !
So, what should you be doing ?
See online info on exam preparation.
Review quizzes. Review notes. Think through topic list.
Prepare your one sheet of notes.
Follow up on stuff that is unclear and
come to the review session  SUNDAY 6-8pm, (location TBA),
and to the discussion session next Monday or to my office hours.
 

Lecture Topics

Review and Exercises

  • Lighting models and Superposition Law: sketch some intensity profiles.
  • Gouraud and Phong Shadingf Techniques: calculate values at some surface points.

    • Procedural Object Generation

    How can you build an interesting object/scene with the least amount of effort ?
    --> Generate vertex and face statements by a program !
    (You will use this approach in Assignment # 9)

    Sweep generators (Review)

    Linear sweep generators, Extruders --> prismatic shapes.
     Rotational sweep generators --> chess figures, tear drops, torus.
    Generalized sweep, mkworm (rocket pilot model).
    Parameterized curves for sweeps; (also for camera motion in movie).

    Introduction to Splines

    Cubic Bezier Curves and B-splines.
    Bicubic Bezier Patches and B-spline surfaces.

    Object modification

    Cut holes in faces ==> frames.
    Put pyramids on faces ==> stars.
    Subdivide faces, project onto sphere ==> geodesic domes.
    Random perturbation of vertices in triangle mesh ==> natural look.
    Fractal surface: recursive refinement and randomization of simple shapes (mountains).
    Volumetric deformations: deform space with encapsulated object: Knots in Coke-Bottles (Sederberg)

    Procedural assembly (instantiation) of objects

    Put together many objects of same shape, perhaps of different scale.
    Iterative placement (gearwheel).
    Recursive placement (Sierpinsky Pyramid, Menger Sponge).
     

    Current Homework Assignment:

    ASG#8  "Lighting Calculations and Gouraud Shading"
    DUE: Saturday 4/10/99, 11:59pm.
    CAN BE DONE WITH YOUR PARTNER OF CHOICE !

    Midterm Exam will be held in class on April 14, 1999.

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