Description of the illustration addci038.gif

The Point Quadtree index structure is illustrated in three successive states. Each Node has four cells that represent four compass points (at positions 1, 2, 3, and 4); these may or may not point to child Nodes.

• State 1:

  • Top (root) Node has a position 1 pointer to a child Node

  • The child Node has a position 3 pointer to Node A

• State 2: Same as State 1, and the following:

  • Top (root) Node has a position 3 pointer to another child Node

  • This child Node has a position 3 pointer to Node B

• State 3: Same as State 2, and the following:

  • Top (root) Node has a position 4 pointer to yet another child Node

  • This child Node has a position 3 pointer to Node C