This sketch illustrates the geometry necessary to calculate the
radius of the detection area, r, within which a bee
flying at a given height, h, will be able to detect a
flower with diameter d, given a resolution of α
≥ 5° (α ≥ 15° for the color recognition area;
r = radius of the circular detection area, sin
α = visual angle subtended by the flower when the bee is
situated at point e).