Elements of 3d Graphics

• Section 1.2
• Most of what we do is vector graphics.
  • But in the end, we must represent in raster.
• In building a world, we generally start by modeling objects.
  • We must do this using the primitives supported by our graphics system.: lines, points, triangles, ...
    • All hail the triangle, tesselator of the plane.
  • These primitives can be modified by changing their attributes
  • In doing this, we most likely model the objects in their own coordinate system.
• These objects can then be combined to form more complex objects.
  • Again, they are probably in their own modeling system.
  • And we will need to use transformations to move from one modeling system to another.
    • Scaling, rotation, translation and others.
• Finally we will assemble multiple objects into a scene
  • This is modeled in world coordinates.
• Building a model out of many parts is called hierarchical modeling
  • An object oriented like approach really
  • Each model has it's own attributes (scale, rotate, color, texture ...)
• The scene may contain non-physical items such as lights
• We then generally introduce a camera from which the scene is viewed.
  • This introduces the camera or viewing coordinate system.
  • We will use a transformation to change from one coordinate system to another.
• After we have everything set up we need to
  • Possibly clip the objects, or remove objects which are not visible to the camera.
  • Project the scene into two dimensions.
• We then rasterize the objects
• At this point we can apply lighting, textures and other coloring techniques.
• And there is an image to display.