Constrained Stress Majorization Using Diagonally Scaled Gradient Projection

Constrained stress majorization is a promising new technique for integrating application specific layout constraints into force directed graph layout. We significantly improve the speed and convergence properties of the constrained stress-majorization technique for graph layout by employing a diagonal scaling of the stress function. Diagonal scaling requires the active-set quadratic programming solver used in the projection step to be extended to handle separation constraints with scaled variables, i.e. of the form s_iy_i + g_ij ≤ s_jy_j. The changes, although relatively small, are quite subtle and explained in detail.