The tracheobronchial tree delivers air through the lungs via successive branching, with each division producing two smaller airways, repeating across many generations until reaching the terminal alveoli. In human lungs, there is an estimated 23 generations from trachea to alveoli.

This model is an implementation of the space-filling algorithm of Kitaoka et al. (1999), capturing approximately 17 generations and 60,000 airway segments.

The purple & green colours denote distinct segments, each supplied by a separate upstream branch.