A 2.5D hierarchical drawing of directed graphs

We introduce a new graph drawing convention for 2.5D hierarchical drawings of directed graphs. The vertex set is partitioned both into layers of vertices drawn in parallel planes and into k ≥ 2 subsets, called walls, and also drawn in parallel planes. The planes of the walls are perpen- dicular to the planes of the layers. We present a method for computing such layouts and introduce five alternative algorithms for partitioning the vertex set into walls which correspond to different aesthetic requirements. We evaluate our method with an extensive computational study.