Ray Tracing Acceleration Based on A survey of ray tracing acceleration techniques by Arvo and Kirk'

1
Ray Tracing Acceleration(Based on A survey of
ray tracing acceleration techniques by Arvo and
Kirk.)
2
Bounding volume algorithm

• procedure Intersect_Bounding_Volume(in ray, node)
• if node is a leaf then
• Intersect(ray, node.object)
• else if Intersect(ray, node.bounding_volume) then
• for each child of node do
• Intersect_Bounding_Volume(ray, child)
• endfor
• endif

3
Uniform grid algorithm

• procedure Grid_Intersect(in ray, node)
• R ? rectangle containing ray.origin
• repeat / walk through grid /
• R ? R
• for each object intersecting rectangle R do
• Intersect(ray, object)
• R ? next rectangle after R intersecting ray
• until (R is last rectangle intersecting ray) or
• (intersection is found in rectangle R)

4
Octree creation algorithm

• procedure Octree_Subdivide(in node)
• if (node intersects more than max_obj objects)
  and (node.depth lt max_depth) then
• Break node.volume into eight octants
• for each octant do
• Create new_node with
• new_node.volume octant
• new_node.depth node.depth1
• Octree_Subdivide(new_node, depth1)
• endfor
• endif

5
Octree intersection algorithm

• procedure Octree_Intersect(in ray)
• R ? rectangle containing ray.origin
• repeat / walk through octree /
• R ? R
• for each object intersecting R do
• Intersect(ray, object)
• R ? next rectangle after R intersecting ray
• until (R is last rectangle intersecting ray) or
• (intersection is found in rectangle R)

6
Binary space partition intersection algorithm

• procedure BSP_Intersect(in ray, node)
• if ray.interval is empty or node is nil then
  return
• if node is a leaf then
• for each object intersecting node.rectangle do
• Intersect(ray, object)
• else
• near ? ray clipped to near side of
  node.partition
• BSP_Intersect(near, node)
• if no intersection found in node.region then
• far ? ray clipped to far side of
  node.partition
• BSP_Intersect(far, node)
• endif
• endif