Fig. 5: Construction of the director fields for cell orientation and contractile stress.

a Cell position and orientation, as shown in Fig. 1. b Cell position and orientation after mapping to a lattice. The lattice unit is equal to \(dl=L/\sqrt{N}\), where L is system size and N is the number of cells in the snapshot. c Linear interpolation is used to find the director field on a lattice with a smaller mesh. This step is required to find the position and orientation of defects correctly. d Using the director on the new lattice, we then use the defect-identifying algorithm introduced in ref. 39 to find the direction and orientation of ±1/2 defects.