(C) Group-Problem#1 (Due 5/21)

We have discussed the 3D-List data structure and the positional/directional spatial 
relationships in class. Extend the 3D-List approach to accommodate the concepts of  
the positional/directional spatial relationships. Define needed operators and work out
associated algorithms in detail.

(D) Group-Problem#2 (Due 5/21)

We have studied several approaches on video retrieval by object trajectories. 
Compare these approaches qualitatively and quantitatively. See whether you could 
come up with a better approach after this comparison.