1. An Adaptive Octree for Ray Tracing by
Octree-R
An Adaptive Octree for Ray Tracing by

2. Ray Tracing Cost Num of voxels to be travel
Num of Ray intersection tests
The time to do intersection test
The time to move from one voxel to next voxel

3. Only to minimize Nt
Assumption:

4. P(B|A)
Average area of projecting volume A to plane with normal d d B

5. Num of Ray intersection tests
Expected Value of Nt

6. Final E(t)

7. Find Dividing Plane 1.Find Object Median(Binary Search)
2.Try k+1 (k=10)plane between
space median and object median
choose the one minimize E(t)
……..

8. Total Algorithm Proc Build_Octree_R 1)Make root_voxel
2)subdivide(root_voxel,MaxObj)
Proc subdivide(voxel,MaxObj)
0)if(voxelNum<MaxObj) return;
1)call Find_Dividing_Plane() for x,y,z axis
2)call subdivide for 8 subvoxel
Proc Find_Dividing_Plane(axis,voxel)
1)Find Object median by binary search with error bound<5%
2)Find Dividing Plane minimize E(t) in k+1 planes which equally spaced between space median and object median

9. Result
Average number of ray objects intersection test

11. Question?
END