Algorithm 6 Merging local K-CoverPicTrees on sensor a

1: Tree(a) = Local K-CoverPicTree of sensor a

2: Tree(b) = Local K-CoverPicTree of sensor b

3: New Combined Tree(a) = []

4: New Combined Tree(a) = Tree(a)

5: for S’ = 1:size(S-common) do

6:    Merge all child nodes of common Node(S’) of Tree(b) into the common Node(S’) of the New Combined Tree(a)

7: end for

8: Call Algorithm 4 to remove redundant photos in the New Combined Tree(a)

9: Requested Photos from sensor b = Photos IDs that generated from subtracting Tree(a) from New Combined Tree(a)

10: Local K-CoverPicTree of sensor a = New Combined Tree(a).