SG Contents

What is stored in a scene graph?

  • objects
  • appearance
  • camera
  • lights

Geometry in the Scene Graph

  • Leafs are basic 3D objects
  • Non-leaf nodes (groups) contain a transformation
    • can have one or several children
    • transformation is given by a homogeneous Matrix
  • Root is the entire world
  • Nodes can be the child of several groups
    • not a tree, but a directed acyclic graph (DAG)
    • effective reuse of geometry

node tree objects

Appearance in the Scene Graph

  • Scene graph also contains appearances
    • Appearance: E.g. Color, reflection, transparency, texture
    • can be reused similarly to geometry
  • Appearance can be only partially specified
    • unspecified values are inherited

node tree appearance

Lights in the Scene Graph

  • Light sources also need a position and/or direction
    • Just include them into the scene graph
    • Can be animated just like geometry
  • Lights can be in local coordinate systems of geometry groups
    • move with them
    • example: lights on a car

node tree lights

The Camera in the Scene Graph

  • Camera also needs a position and direction
    • Just include it into the scene graph
    • Can be animated just like geometry
  • Camera can be in local coordinate systems of geometry groups
    • move with them
    • example: driver‘s view from a car

node tree camera

Spatial Partitioning

Binary Spatial Partitioning