Quadtrees A and B can be efficiently intersected:

• If A = 0 or B = 0, the result is 0.
• If A = 1, the result is B.
• If B = 1, the result is A.
• Otherwise, make a new interior node whose values are corresponding intersections of children of A and B.

Notice that the intersection can often reuse parts of the input trees. Uses include:

• Geospatial modeling, e.g. what is the intersection of area of forecast rain with area of corn?
• Graphics, games: view frustum culling
• Collision detection

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