Sketch illustrating the counting of pairs within a circular domain of analysis of radius R represented by the large black circle. Within this domain, the centroid shift C(θ) takes values determined by the stochastic turbulent field, while we set C = 0 outside. Counting inner pairs (shown with green and red sticks) separated by a distance s is performed by computing the range of accessible angles ϕ_s(θ) for a given position in the domain, then dividing by two. External pairs have only one end within the domain of analysis and the range of accessible angles is 2π − ϕ_s at a given position.