Alexander Gustaveson, writing on ILM, about the digital work done on Rogue One:
Much of the work in Post Visual Development is pure design. We design digital environments and sets, we alter designs from pre-production, we create ships, weapons, and creatures.
Designing digital environments after plate photography allows flexibility in storytelling. For example: the Citadel sequence. The modular design and concentric circles allowed Gareth visual cheats: a character can jump huge distances geographically as needed for the plot, but the audience is not lost visually because the symmetry of the design.