CS 285: SOLID MODELING

Lecture #6 -- Mo, Feb. 6, 2006.

Warm-up Exercise: What is the Symmetry Group of these Objects ?

Brain teaser: -- Why does an ordinary wall mirror reverse left and right, but not up and down ?

Visualization of Symmetry Groups Using Shape Generator Programs

Understanding Chart I:  with "Sculpture Generator I"

Understanding Chart II:  with "Escher Sphere Editor"

From a Graphical Design to a Realizable 3D Solid Part

• Need to distill out an individual tile;
• Need to give the tile some thickness,
• and possibly some relief in the form of a height field;
• Need to provide a (possibly simpler) back-surface;
• Need to connect these two surfaces into a coherent B-rep with side walls;
• Also may have to figure out a coloring pattern for the various tiles.
  

Representations for Solid Modeling

• What is easiest way for the designer to describe the part:
  -- instancing, boolean operations, maintain symmetry, allow controlled space warps, ...
  
• What is the best way to visualize the result of a designer's input:
  -- interactive speed, resolve booleans to screen resolution, rendering enhancements: shadows, depth queues ...
  
• How can a possible design most easily be analyzed for consistency, volume, weight distribution, srength, ...:
  -- need to deal with volumetric information explicitly: tetrahedralization, finite-element meshing, voxelization, ...
  
• How can the finished design best be transmitted to someone else:
  -- description needs to be unambiguous, precise, efficient, easy to parse and process, ...  (unlike .STL).
  
• What is the best representation for the manufacturing process:
  --  primitives relevant to the manufacturing process -- strongly depends on type of process:
• Layered manufacturing:  Collection of 2D contours or raster maps corresponding to each slice level.
• Machining on a milling machine:  Starting shape plus a collection of features (pockets, drill holes) that need to be removed.
  
  

New Homework Assignment#4:

Pick your FIVE favorite papers for in-class presentation from the handed-out collection.
(This is your opportunity to influence the contents and focus of this course offering.)

Due Wednesday 2/8/2006.