Pixar painstakingly designed the "Oozma Kappa" fraternity house to look like a lived-in, 1980s college dump. In SD, the clutter just looks like noise. But in HD, you can read the posters on the walls, see the scuff marks on the wooden floors, and notice the dust motes floating in the afternoon light. This environmental storytelling is only fully appreciated at high resolution.
Pixar developed a new lighting technology for this film that allowed them to change the mood of an entire scene with just a few clicks, making the process much faster than their previous layered methods. Why the Story Matters Monster University Hd