Lecture_Chapter6_b

# On viewing positionorientation visibility tests tree

This preview shows page 1. Sign up to view the full content.

This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ruction A C1 B1 D3 D1 E1 B2 D2 C2 E2 G3 G2 G1 F E3 ECS 175 Chapter 6: Scene Representation and Interaction 43 BSP Tree •  BSP-Tree Applications •  Painter’s algorithm (sorting) •  Planes sort objects into (“behind” and “in front”) •  Tree traversal dependent on viewing position/orientation •  Visibility tests •  Tree computation is performed offline •  Tree computation as pre-processing •  Visibility information between nodes •  Drawbacks: •  Increases number of polygons •  Requires costly ordering and intersecting •  Assumes static geometry ECS 175 Chapter 6: Scene Representation and Interaction 44 Quadtrees and Octrees •  Quadtrees subdivide space in a predefined way parents have four child nodes axis aligned separation planes cell widths are halved ECS 175 Chapter 6: Scene Representation and Interaction 45 Quadtrees and Octrees •  Quadtree example: •  Image compression •  Octrees (in 3D) have eight child nodes per parent ECS 175 Chapter 6: Scene Representation and Interaction 46 Quadtrees and Octrees •  Quadtree example: •  Hierarchical collision test ECS 175 Chapter 6: Scene Representation and Interaction 47 Scene Representation - Summary •  Scenes consist of multiple objects in the same frame •  Hierarchical representations (trees) are important for •  Compound/Mechanical objects •  Kinematic skeleton/chain represents relative transformations •  Scene composition using a scene graph •  Hierarchical, object-oriented representation •  Object instancing, relative properties •  Can be combined with spatial partitioning technique •  Spatial partitioning/Spatial subdivision •  Pre-computed visibility tests •  Pre-computed relative ordering •  Hierarchical representation (compression) •  Hierarchical spatial operations (collision test) ECS 175 Chapter 6: Scene Representation and Interaction 48...
View Full Document

## This document was uploaded on 03/12/2014 for the course ECS 175 at UC Davis.

Ask a homework question - tutors are online