lgorithms for computing the Voronoi diagram
Divide and conquer - algorithm divides the points into right and left part, it recursively computes a Voronoi diagram for these two parts and finally it "merges" these two parts by computing voronoi lines between them.
Incremental algorithm - it counts a Voronoi diagram for two sites. Then it takes other sites, one by one, and edits current diagram.
These algorithms have many disadvantages - difficult implementation, nontrivial merging of diagrams, numerical inaccuracy.